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Genetics of Breast and Ovarian Cancer (PDQ®)

  • Last Modified: 07/11/2014

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Table of Contents

Introduction

High-Penetrance Breast and/or Ovarian Cancer Susceptibility Genes

Low- and Moderate-Penetrance Genes Associated With Breast and/or Ovarian Cancer
Background
Breast Cancer Susceptibility Genes Identified Through Candidate Gene Approaches
        CHEK2
        ATM
        BRIP1
        PALB2
        CASP8 and TGFB1
        RAD51
        Abraxas
Genome-Wide Searches

Psychosocial Issues in Inherited Breast Cancer Syndromes

Changes to This Summary (07/11/2014)

About This PDQ Summary

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Introduction



General Information

 [Note: Many of the medical and scientific terms used in this summary are found in the NCI Dictionary of Genetics Terms. When a linked term is clicked, the definition will appear in a separate window.]

 [Note: Many of the genes and conditions described in this summary are found in the Online Mendelian Inheritance in Man (OMIM) database. When OMIM appears after a gene name or the name of a condition, click on OMIM for a link to more information.]

Among women, breast cancer is the most commonly diagnosed cancer after nonmelanoma skin cancer, and it is the second leading cause of cancer deaths after lung cancer. In 2014, an estimated 235,030 new cases will be diagnosed, and 40,430 deaths from breast cancer will occur.[1] The incidence of breast cancer, particularly for estrogen receptor–positive cancers occurring after age 50 years, is declining and has declined at a faster rate since 2003; this may be temporally related to a decrease in hormone replacement therapy (HRT) after early reports from the Women’s Health Initiative (WHI).[2] An estimated 21,980 new cases of ovarian cancer are expected in 2014, with an estimated 14,270 deaths. Ovarian cancer is the fifth most deadly cancer in women.[1] (Refer to the PDQ summaries on Breast Cancer Treatment and Ovarian Epithelial Cancer Treatment for more information about breast cancer and ovarian cancer rates, diagnosis, and management.)

A possible genetic contribution to both breast and ovarian cancer risk is indicated by the increased incidence of these cancers among women with a family history (see the Family History as a Risk Factor for Breast Cancer and the Family History as a Risk Factor for Ovarian Cancer sections below), and by the observation of some families in which multiple family members are affected with breast and/or ovarian cancer, in a pattern compatible with an inheritance of autosomal dominant cancer susceptibility. Formal studies of families (linkage analysis) have subsequently proven the existence of autosomal dominant predispositions to breast and ovarian cancer and have led to the identification of several highly penetrant genes as the cause of inherited cancer risk in many families. (Refer to the PDQ summary Cancer Genetics Overview for more information about linkage analysis.) Mutations in these genes are rare in the general population and are estimated to account for no more than 5% to 10% of breast and ovarian cancer cases overall. It is likely that other genetic factors contribute to the etiology of some of these cancers.

Family History as a Risk Factor for Breast Cancer

In cross-sectional studies of adult populations, 5% to 10% of women have a mother or sister with breast cancer, and about twice as many have either a first-degree relative (FDR) or a second-degree relative with breast cancer.[3-6] The risk conferred by a family history of breast cancer has been assessed in case-control and cohort studies, using volunteer and population-based samples, with generally consistent results.[7] In a pooled analysis of 38 studies, the relative risk (RR) of breast cancer conferred by an FDR with breast cancer was 2.1 (95% confidence interval [CI], 2.0–2.2).[7] Risk increases with the number of affected relatives, age at diagnosis, and the number of affected male relatives.[4,5,7,8] (Refer to the Penetrance of mutations section of this summary for a discussion of familial risk in women from families with BRCA1/BRCA2 mutations who themselves test negative for the family mutation.)

Family History as a Risk Factor for Ovarian Cancer

Although reproductive, demographic, and lifestyle factors affect risk of ovarian cancer, the single greatest ovarian cancer risk factor is a family history of the disease. A large meta-analysis of 15 published studies estimated an odds ratio of 3.1 for the risk of ovarian cancer associated with at least one FDR with ovarian cancer.[9]

Autosomal Dominant Inheritance of Breast/Ovarian Cancer Predisposition

Autosomal dominant inheritance of breast/ovarian cancer is characterized by transmission of cancer predisposition from generation to generation, through either the mother’s or the father’s side of the family, with the following characteristics:

  • Inheritance risk of 50%. When a parent carries an autosomal dominant genetic predisposition, each child has a 50:50 chance of inheriting the predisposition. Although the risk of inheriting the predisposition is 50%, not everyone with the predisposition will develop cancer because of incomplete penetrance and/or gender-restricted or gender-related expression.

  • Both males and females can inherit and transmit an autosomal dominant cancer predisposition. A male who inherits a cancer predisposition can still pass the altered gene on to his sons and daughters.

Breast and ovarian cancer are components of several autosomal dominant cancer syndromes. The syndromes most strongly associated with both cancers are the BRCA1 or BRCA2 mutation syndromes. Breast cancer is also a common feature of Li-Fraumeni syndrome due to TP53 mutations and of Cowden syndrome due to PTEN mutations.[10] Other genetic syndromes that may include breast cancer as an associated feature include heterozygous carriers of the ataxia telangiectasia gene and Peutz-Jeghers syndrome. Ovarian cancer has also been associated with Lynch syndrome, basal cell nevus (Gorlin) syndrome (OMIM), and multiple endocrine neoplasia type 1 (OMIM).[10] Germline mutations in the genes responsible for those syndromes produce different clinical phenotypes of characteristic malignancies and, in some instances, associated nonmalignant abnormalities.

The family characteristics that suggest hereditary breast and ovarian cancer predisposition include the following:

  • Multiple cancers within a family.

  • Cancers typically occur at an earlier age than in sporadic cases (defined as cases not associated with genetic risk).

  • Two or more primary cancers in a single individual. These could be multiple primary cancers of the same type (e.g., bilateral breast cancer) or primary cancer of different types (e.g., breast cancer and ovarian cancer in the same individual).

  • Cases of male breast cancer.

Figure 1 and Figure 2 depict some of the classic inheritance features of a deleterious BRCA1 and BRCA2 mutation, respectively. (Refer to the Standard Pedigree Nomenclature figure in the PDQ summary on Cancer Genetics Risk Assessment and Counseling for definitions of the standard symbols used in these pedigrees.)

Enlarge
Pedigree showing some of the classic features of a family with a deleterious BRCA1 mutation across three generations, including transmission occurring through maternal and paternal lineages. The unaffected female proband is shown as having an affected mother (breast cancer diagnosed at age 42 y), female cousin (breast cancer diagnosed at age 38 y), maternal aunt (ovarian cancer diagnosed at age 53 y), and maternal grandmother (ovarian cancer diagnosed at age 49 y).
Figure 1. BRCA1 pedigree. This pedigree shows some of the classic features of a family with a deleterious BRCA1 mutation across three generations, including affected family members with breast cancer or ovarian cancer and a young age at onset. BRCA1 families may exhibit some or all of these features. As an autosomal dominant syndrome, transmission can occur through maternal or paternal lineages, as depicted in the figure.
Enlarge
Pedigree showing some of the classic features of a family with a deleterious BRCA2 mutation across three generations, including transmission occuring through maternal and paternal lineages. The unaffected female proband is shown as having an affected brother (breast cancer diagnosed at age 52 y), mother (breast cancer diagnosed at age 45 y and pancreatic cancer diagnosed at age 55 y), maternal aunt (ovarian cancer diagnosed at age 58 y), and maternal grandfather (prostate cancer diagnosed at age 55 y).
Figure 2. BRCA2 pedigree. This pedigree shows some of the classic features of a family with a deleterious BRCA2 mutation across three generations, including affected family members with breast (including male breast cancer), ovarian, pancreatic, or prostate cancers and a relatively young age at onset. BRCA2 families may exhibit some or all of these features. As an autosomal dominant syndrome, transmission can occur through maternal or paternal lineages, as depicted in the figure.

There are no pathognomonic features distinguishing breast and ovarian cancers occurring in BRCA1 or BRCA2 mutation carriers from those occurring in noncarriers. Breast cancers occurring in BRCA1 mutation carriers are more likely to be estrogen receptor (ER)-negative, progesterone receptor–negative, and HER2/neu receptor-negative and have a basal phenotype. BRCA1-associated ovarian cancers are more likely to be high-grade and of serous histopathology. (Refer to the Pathology of breast cancer and Pathology of ovarian cancer sections of this summary for more information.)

Difficulties in Identifying a Family History of Breast and Ovarian Cancer Risk

When using family history to assess risk, the accuracy and completeness of family history data must be taken into account. A reported family history may be erroneous, or a person may be unaware of relatives affected with cancer. In addition, small family sizes and premature deaths may limit the information obtained from a family history. Breast or ovarian cancer on the paternal side of the family usually involves more distant relatives than on the maternal side and thus may be more difficult to obtain. When comparing self-reported information with independently verified cases, the sensitivity of a history of breast cancer is relatively high, at 83% to 97%, but lower for ovarian cancer, at 60%.[11,12]

Other Risk Factors for Breast Cancer

Other risk factors for breast cancer include age, reproductive and menstrual history, hormone therapy, radiation exposure, mammographic breast density, alcohol intake, physical activity, anthropometric variables, and a history of benign breast disease. (Refer to the PDQ summary on Breast Cancer Prevention for more information.) These factors, including their role in the etiology of breast cancer among BRCA1/BRCA2 mutation carriers, are considered in more detail in other reviews.[13-15] Brief summaries are given below, highlighting, where possible, the effect of these risk factors in women who are genetically susceptible to breast cancer. (Refer to the Clinical management of BRCA mutation carriers section of this summary for more information about their effects in BRCA1/BRCA2 mutation carriers.)

Age

Cumulative risk of breast cancer increases with age, with most breast cancers occurring after age 50 years.[16] In women with a genetic susceptibility, breast cancer, and to a lesser degree, ovarian cancer, tends to occur at an earlier age than in sporadic cases.

Reproductive and menstrual history

In general, breast cancer risk increases with early menarche and late menopause and is reduced by early first full-term pregnancy. In BRCA1 and BRCA2 mutation carriers, results have been conflicting and may be gene dependent. No consistent significant associations have been observed.[15,17-19] Evidence suggests that reproductive history may be differentially associated with breast cancer subtype (i.e., triple-negative vs. ER-positive breast cancers). In contrast to ER-positive breast cancers, parity has been positively associated with triple-negative disease, with no association with ages at menarche and menopause.[20]

Oral contraceptives

Oral contraceptives (OCs) may produce a slight increase in breast cancer risk among long-term users, but this appears to be a short-term effect. In a meta-analysis of data from 54 studies, the risk of breast cancer associated with OC use did not vary in relationship to a family history of breast cancer.[21]

OCs are sometimes recommended for ovarian cancer prevention in BRCA1 and BRCA2 mutation carriers. Although the data are not entirely consistent, a meta-analysis concluded that there was no significant increased risk of breast cancer with OC use in BRCA1/BRCA2 mutation carriers.[22] However, use of OCs formulated before 1975 was associated with an increased risk of breast cancer (summary relative risk [SRR], 1.47; 95% CI, 1.06–2.04).[22] (Refer to the Reproductive factors section in the Clinical management of BRCA mutation carriers section of this summary for more information.)

Hormone replacement therapy

Data exist from both observational and randomized clinical trials regarding the association between postmenopausal HRT and breast cancer. A meta-analysis of data from 51 observational studies indicated a RR of breast cancer of 1.35 (95% CI, 1.21–1.49) for women who had used HRT for 5 or more years after menopause.[23] The WHI, a randomized controlled trial (NCT00000611) of about 160,000 postmenopausal women, investigated the risks and benefits of HRT. The estrogen-plus-progestin arm of the study, in which more than 16,000 women were randomly assigned to receive combined HRT or placebo, was halted early because health risks exceeded benefits.[24,25] Adverse outcomes prompting closure included significant increase in both total (245 vs. 185 cases) and invasive (199 vs. 150 cases) breast cancers (RR, 1.24; 95% CI, 1.02–1.5, P <. 001) and increased risks of coronary heart disease, stroke, and pulmonary embolism. Similar findings were seen in the estrogen-progestin arm of the prospective observational Million Women’s Study in the United Kingdom.[26] The risk of breast cancer was not elevated, however, in women randomly assigned to estrogen-only versus placebo in the WHI study (RR, 0.77; 95% CI, 0.59–1.01). Eligibility for the estrogen-only arm of this study required hysterectomy, and 40% of these patients also had undergone oophorectomy, which potentially could have impacted breast cancer risk.[27]

The association between HRT and breast cancer risk among women with a family history of breast cancer has not been consistent; some studies suggest risk is particularly elevated among women with a family history, while others have not found evidence for an interaction between these factors.[28-32,23] The increased risk of breast cancer associated with HRT use in the large meta-analysis did not differ significantly between subjects with and without a family history.[32] The WHI study has not reported analyses stratified on breast cancer family history, and subjects have not been systematically tested for BRCA1/BRCA2 mutations.[25] Short-term use of hormones for treatment of menopausal symptoms appears to confer little or no breast cancer risk.[23,33] The effect of HRT on breast cancer risk among carriers of BRCA1 or BRCA2 mutations has been studied only in the context of bilateral risk-reducing oophorectomy, in which short-term replacement does not appear to reduce the protective effect of oophorectomy on breast cancer risk.[34] (Refer to the Hormone replacement therapy in BRCA1/BRCA2 mutation carriers section of this summary for more information.)

Radiation exposure

Observations in survivors of the atomic bombings of Hiroshima and Nagasaki and in women who have received therapeutic radiation treatments to the chest and upper body document increased breast cancer risk as a result of radiation exposure. The significance of this risk factor in women with a genetic susceptibility to breast cancer is unclear.

Preliminary data suggest that increased sensitivity to radiation could be a cause of cancer susceptibility in carriers of BRCA1 or BRCA2 mutations,[35-38] and in association with germline ATM and TP53 mutations.[39,40]

The possibility that genetic susceptibility to breast cancer occurs via a mechanism of radiation sensitivity raises questions about radiation exposure. It is possible that diagnostic radiation exposure, including mammography, poses more risk in genetically susceptible women than in women of average risk. Therapeutic radiation could also pose carcinogenic risk. A cohort study of BRCA1 and BRCA2 mutation carriers treated with breast-conserving therapy, however, showed no evidence of increased radiation sensitivity or sequelae in the breast, lung, or bone marrow of mutation carriers.[41] Conversely, radiation sensitivity could make tumors in women with genetic susceptibility to breast cancer more responsive to radiation treatment. Studies examining the impact of radiation exposure, including, but not limited to, mammography, in BRCA1 and BRCA2 mutation carriers have had conflicting results.[42-46] A large European study showed a dose-response relationship of increased risk with total radiation exposure, but this was primarily driven by nonmammographic radiation exposure before age 20 years.[46] (Refer to the Mammography section in the High-Penetrance Breast and/or Ovarian Cancer Susceptibility Genes section of this summary for more information about radiation.)

Alcohol intake

The risk of breast cancer increases by approximately 10% for each 10 g of daily alcohol intake (approximately one drink or less) in the general population.[47,48] Prior studies of BRCA1/BRCA2 mutation carriers have found no increased risk associated with alcohol consumption.[49,50]

Physical activity and anthropometry

Weight gain and being overweight are commonly recognized risk factors for breast cancer. In general, overweight women are most commonly observed to be at increased risk of postmenopausal breast cancer and at reduced risk of premenopausal breast cancer. Sedentary lifestyle may also be a risk factor.[51] These factors have not been systematically evaluated in women with a positive family history of breast cancer or in carriers of cancer-predisposing mutations, but one study suggested a reduced risk of cancer associated with exercise among BRCA1 and BRCA2 mutation carriers.[52]

Benign breast disease and mammographic density

Benign breast disease (BBD) is a risk factor for breast cancer, independent of the effects of other major risk factors for breast cancer (age, age at menarche, age at first live birth, and family history of breast cancer).[53] There may also be an association between BBD and family history of breast cancer.[54]

An increased risk of breast cancer has also been demonstrated for women who have increased density of breast tissue as assessed by mammogram,[53,55,56] and breast density is likely to have a genetic component in its etiology.[57-59]

Other factors

Other risk factors, including those that are only weakly associated with breast cancer and those that have been inconsistently associated with the disease in epidemiologic studies (e.g., cigarette smoking), may be important in women who are in specific genotypically defined subgroups. For example, some studies have suggested that certain N-acetyl transferase alleles may influence female smokers’ risk of developing breast cancer.[60] One study [61] found a reduced risk of breast cancer among BRCA1/BRCA2 mutation carriers who smoked, but an expanded follow-up study failed to find an association.[62]

Other Risk Factors for Ovarian Cancer

Factors that increase risk of ovarian cancer include increasing age and nulliparity, while those that decrease risk include surgical history and use of OCs.[63,64] (Refer to the PDQ summary on Prevention of Ovarian Cancer for more information.) Relatively few studies have addressed the effect of these risk factors in women who are genetically susceptible to ovarian cancer. (Refer to the Reproductive factors section of this summary for more information.)

Age

Ovarian cancer incidence rises in a linear fashion from age 30 years to age 50 years and continues to increase, though at a slower rate, thereafter. Before age 30 years, the risk of developing epithelial ovarian cancer is remote, even in hereditary cancer families.[65]

Reproductive history

Nulliparity is consistently associated with an increased risk of ovarian cancer, including among BRCA1/BRCA2 mutation carriers.[66] Risk may also be increased among women who have used fertility drugs, especially those who remain nulligravid.[63,67] Evidence is growing that the use of menopausal HRT is associated with an increased risk of ovarian cancer, particularly in long-time users and users of sequential estrogen-progesterone schedules.[68-71]

Surgical history

Bilateral tubal ligation and hysterectomy are associated with reduced ovarian cancer risk,[63,72,73] including in BRCA1/BRCA2 mutation carriers.[74] Ovarian cancer risk is reduced more than 90% in women with documented BRCA1 or BRCA2 mutations who chose risk-reducing salpingo-oophorectomy. In this same population, prophylactic removal of the ovaries also resulted in a nearly 50% reduction in the risk of subsequent breast cancer.[75,76] (Refer to the Risk-reducing salpingo-oophorectomy section of this summary for more information about these studies.)

Oral contraceptives

Use of OCs for 4 or more years is associated with an approximately 50% reduction in ovarian cancer risk in the general population.[63,64] A majority of, but not all, studies also support OCs being protective among BRCA1/ BRCA2 mutation carriers.[66,77-80] A meta-analysis of 18 studies including 13,627 BRCA mutation carriers reported a significantly reduced risk of ovarian cancer (SRR, 0.50; 95% CI, 0.33–0.75) associated with OC use.[22] (Refer to the Oral contraceptives section in the Chemoprevention section of this summary for more information.)

Models for Prediction of Breast Cancer Risk

Models to predict an individual’s lifetime risk of developing breast cancer are available.[81,82] In addition, models exist to predict an individual’s likelihood of having a BRCA1 or BRCA2 mutation. (Refer to the Models for prediction of the likelihood of a BRCA1 or BRCA2 mutation section of this summary for more information about these models.) Not all models can be appropriately applied for all patients. Each model is appropriate only when the patient’s characteristics and family history are similar to the study population on which the model was based. Different models may provide widely varying risk estimates for the same clinical scenario, and the validation of these estimates has not been performed for many models.[82,83] Table 1 summarizes the salient aspects of two of the common risk assessment models and is designed to aid in choosing the model that best applies to a particular individual.

The Claus model [84,85] and the Gail model [86] are widely used in research studies and clinical counseling. Both have limitations, and the risk estimates derived from the two models may differ for an individual patient. Several other models, which include more detailed family history information, are also in use and are discussed below.

Table 1. Characteristics of the Gail and Claus Modelsa
 Gail Model (Breast Cancer Risk Assessment Tool)b Claus Model 
Data derived from Breast Cancer Detection Demonstration Project StudyCancer and Steroid Hormone Study
Study population 2,852 cases, aged ≥35 y4,730 cases, aged 20–54 y
In situ and invasive cancerInvasive cancer
3,146 controls4,688 controls
CaucasianCaucasian
Annual breast screeningNot routinely screened
Family history characteristics FDRs with breast cancerFDRs or SDRs with breast cancer
Age of onset in relatives
Other characteristics Current ageCurrent age
Age at menarche
Age at first live birth
Number of breast biopsies
Atypical hyperplasia in breast biopsy
Race (included in the most current version of the Gail model)
Strengths Incorporates:Incorporates:
Risk factors other than family historyPaternal and maternal history
Age at onset of breast cancer
Family history of ovarian cancer
Limitations Underestimates risk in hereditary familiesMay underestimate risk in hereditary families
Number of breast biopsies without atypical hyperplasia may cause inflated risk estimatesMay not be applicable to all combinations of affected relatives
Does not include risk factors other than family history
Does not incorporate:
Paternal family history of breast cancer or any family history of ovarian cancer
Age at onset of breast cancer in relatives
All known risk factors for breast cancer [89]
Best application For individuals with no family history of breast cancer or one FDR with breast cancer, aged ≥50 yFor individuals with no more than two FDRs or SDRs with breast cancer
For determining eligibility for chemoprevention studies

FDR = first-degree relative; SDR = second-degree relative.
aAdapted from Domchek et al.,[87] Rubenstein et al.,[88] and Rhodes.[89]
bModified based on periodic updates.[90,91]

The Gail and the Claus models will significantly underestimate breast cancer risk in women from families with hereditary breast cancer susceptibility syndromes. Generally, the Claus or the Gail models should not be the sole model used for families with one or more of the following characteristics:

  • Three individuals with breast or ovarian cancer (especially when one or more breast cancers are diagnosed before age 50 years).
  • A woman who has both breast and ovarian cancer.
  • Ashkenazi Jewish ancestry with at least one case of breast or ovarian cancer (as these families are more likely to have a hereditary cancer susceptibility syndrome).

The Gail model is the basis for the Breast Cancer Risk Assessment Tool, a computer program that is available from the National Cancer Institute by calling the Cancer Information Service at 1-800-4-CANCER (1-800-422-6237). This version of the Gail model estimates only the risk of invasive breast cancer. The Gail model has been found to be reasonably accurate at predicting breast cancer risk in large groups of white women who undergo annual screening mammography; however, reliability varies based on the cohort studied.[91-96] Risk can be overestimated in:

  • Women who do not adhere to screening recommendations.[92,93]
  • Women in the highest risk strata.[95]

Risk could be underestimated in the lowest risk strata.[95] Earlier studies [92,93] suggested risk was overestimated in younger women and underestimated in older women. More recent studies [94,95] using the modified Gail model (which is currently used) found it performed well in all age groups. Further studies are needed to establish the validity of the Gail model in minority populations.[96] Recently, modifications have been made to the Breast Cancer Risk Assessment Tool incorporating data from the Women’s Contraceptive and Reproductive Experiences study. This study of more than 1,600 African American women with invasive breast cancer and more than 1,600 controls was used to develop a breast cancer risk assessment model with improved race-specific calibration.[90] Additional information for seven common low-penetrance breast cancer susceptibility alleles has not been shown to improve model performance significantly.[97,98]

A study of 491 women aged 18 to 74 years with a family history of breast cancer compared the most recent Gail model to the Claus model in predicting breast cancer risk.[99] The two models were positively correlated (r = .55). The Gail model estimates were higher than the Claus model estimates for most participants. Presentation and discussion of both the Gail and Claus models risk estimates may be useful in the counseling setting.

The Tyrer-Cuzick model incorporates both genetic and nongenetic factors.[100] A three-generation pedigree is used to estimate the likelihood that an individual carries either a BRCA1/BRCA2 mutation or a hypothetical low-penetrance gene. In addition, the model incorporates personal risk factors such as parity, body mass index, height, and age at menarche, menopause, HRT use, and first live birth. Both genetic and nongenetic f actors are combined to develop a risk estimate. Although powerful, the model at the current time is less accessible to primary care providers than the Gail and Claus models. The Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm model examines family history to estimate breast cancer risk and also incorporates both BRCA1/BRCA2 and non-BRCA1/BRCA2 genetic risk factors.[101]

Other risk assessment models incorporating breast density have been developed but are not ready for clinical use.[102,103] In the future, additional models may be developed or refined to include such factors as breast density and other biomarkers.

Available Clinical Practice Guidelines for Hereditary Breast and Ovarian Cancer

Table 2 lists several organizations that have published recommendations for cancer risk assessment and genetic counseling, genetic testing, and/or management for hereditary breast and ovarian cancer.

Table 2. Available Clinical Practice Guidelines for Hereditary Breast and Ovarian Cancer (HBOC)
Organization Risk Assessment and Genetic Counseling Recommendations Genetic Testing Recommendations Management Recommendations 
ACOG (2009) [104]Risk Assessment: AddressedNot addressedAddressed
Genetic Counseling: Addressed
ASCO (2010) [105]Risk Assessment: General recommendations; not specific to HBOCGeneral recommendations; not specific to HBOCNot addressed
Genetic Counseling: Addressed
NAPBC (2013) [106]Risk Assessment: Refers to other published guidelinesIndications for testing not addressed; components of pretest and posttest counseling addressedNot addressed
Genetic Counseling: Addressed
NSGC (2013) [107]Risk Assessment: Refers to other published guidelines and available modelsAddressedRefers to other published guidelines
Genetic Counseling: Addressed
NCCN (2014) [108]Risk Assessment: AddressedAddressedAddressed
Genetic Counseling: Addressed
SGO (2014) [109]Risk Assessment: AddressedAddressedAddressed in general terms
Genetic Counseling: Addressed
USPSTFa (2014) [110]Risk Assessment: AddressedAddressed in general terms and other guidelines referencedAddressed in general terms and other guidelines referenced
Genetic Counseling: Addressed

ACOG = American College of Obstetricians and Gynecologists; ASCO = American Society of Clinical Oncology; NAPBC = National Accreditation Program for Breast Centers; NCCN = National Comprehensive Cancer Network; NSGC = National Society of Genetic Counselors; SGO = Society of Gynecologic Oncology; USPSTF = U.S. Preventive Services Task Force.
aThe USPSTF guidelines apply to individuals without a prior cancer diagnosis.

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  76. Rebbeck TR, Lynch HT, Neuhausen SL, et al.: Prophylactic oophorectomy in carriers of BRCA1 or BRCA2 mutations. N Engl J Med 346 (21): 1616-22, 2002.  [PUBMED Abstract]

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High-Penetrance Breast and/or Ovarian Cancer Susceptibility Genes



BRCA1 and BRCA2

Introduction

Epidemiologic studies have clearly established the role of family history as an important risk factor for both breast and ovarian cancer. After gender and age, a positive family history is the strongest known predictive risk factor for breast cancer. However, it has long been recognized that in some families, there is hereditary breast cancer, which is characterized by an early age of onset, bilaterality, and the presence of breast cancer in multiple generations in an apparent autosomal dominant pattern of transmission (through either the maternal or paternal lineage), sometimes including tumors of other organs, particularly the ovary and prostate gland.[1,2] It is now known that some of these “cancer families” can be explained by specific mutations in single cancer susceptibility genes. The isolation of several of these genes, which when mutated are associated with a significantly increased risk of breast/ovarian cancer, makes it possible to identify individuals at risk. Although such cancer susceptibility genes are very important, highly penetrant germline mutations are estimated to account for only 5% to 10% of breast cancers overall.

A 1988 study reported the first quantitative evidence that breast cancer segregated as an autosomal dominant trait in some families.[3] The search for genes associated with hereditary susceptibility to breast cancer has been facilitated by studies of large kindreds with multiple affected individuals and has led to the identification of several susceptibility genes, including BRCA1, BRCA2, TP53, PTEN/MMAC1, and STK11. Other genes, such as the mismatch repair genes MLH1, MSH2, MSH6, and PMS2, have been associated with an increased risk of ovarian cancer, but have not been consistently associated with breast cancer.

BRCA1

In 1990, a susceptibility gene for breast cancer was mapped by genetic linkage to the long arm of chromosome 17, in the interval 17q12-21.[4] The linkage between breast cancer and genetic markers on chromosome 17q was soon confirmed by others, and evidence for the coincident transmission of both breast and ovarian cancer susceptibility in linked families was observed.[5] The BRCA1 gene (OMIM) was subsequently identified by positional cloning methods and has been found to contain 24 exons that encode a protein of 1,863 amino acids. Germline mutations in BRCA1 are associated with early-onset breast cancer, ovarian cancer, and fallopian tube cancer. (Refer to the Penetrance of mutations section of this summary for more information.) Male breast cancer, pancreatic cancer, testicular cancer, and early-onset prostate cancer may also be associated with mutations in BRCA1;[6-9] however, male breast cancer, pancreatic cancer, and prostate cancer are more strongly associated with mutations in BRCA2.

BRCA2

A second breast cancer susceptibility gene, BRCA2, was localized to the long arm of chromosome 13 through linkage studies of 15 families with multiple cases of breast cancer that were not linked to BRCA1. Mutations in BRCA2 (OMIM) are associated with multiple cases of breast cancer in families, and are also associated with male breast cancer, ovarian cancer, prostate cancer, melanoma, and pancreatic cancer.[8-14] (Refer to the Penetrance of mutations section of this summary for more information.) BRCA2 is a large gene with 27 exons that encode a protein of 3,418 amino acids.[15] While not homologous genes, both BRCA1 and BRCA2 have an unusually large exon 11 and translational start sites in exon 2. Like BRCA1, BRCA2 appears to behave like a tumor suppressor gene. In tumors associated with both BRCA1 and BRCA2 mutations, there is often loss of the wild-type (nonmutated) allele.

Mutations in BRCA1 and BRCA2 appear to be responsible for disease in 45% of families with multiple cases of breast cancer only and in up to 90% of families with both breast and ovarian cancer.[16]

BRCA1 and BRCA2 function

Most BRCA1 and BRCA2 mutations are predicted to produce a truncated protein product, and thus loss of protein function, although some missense mutations cause loss of function without truncation. Because inherited breast/ovarian cancer is an autosomal dominant condition, persons with a BRCA1 or BRCA2 mutation on one copy of chromosome 17 or 13 also carry a normal allele on the other paired chromosome. In most breast and ovarian cancers that have been studied from mutation carriers, deletion of the normal allele results in loss of all function, leading to the classification of BRCA1 and BRCA2 as tumor suppressor genes. In addition to, and as part of, their roles as tumor suppressor genes, BRCA1 and BRCA2 are involved in myriad functions within cells, including homologous DNA repair, genomic stability, transcriptional regulation, protein ubiquitination, chromatin remodeling, and cell cycle control.[17,18]

Mutations in BRCA1 and BRCA2

Nearly 2,000 distinct mutations and sequence variations in BRCA1 and BRCA2 have already been described.[19] Approximately one in 400 to 800 individuals in the general population may carry a pathogenic germline mutation in BRCA1 or BRCA2.[20,21] The mutations that have been associated with increased risk of cancer result in missing or nonfunctional proteins, supporting the hypothesis that BRCA1 and BRCA2 are tumor suppressor genes. While a small number of these mutations have been found repeatedly in unrelated families, most have not been reported in more than a few families.

Mutation-screening methods vary in their sensitivity. Methods widely used in research laboratories, such as single-stranded conformational polymorphism analysis and conformation-sensitive gel electrophoresis, miss nearly a third of the mutations that are detected by DNA sequencing.[22] In addition, large genomic alterations such as translocations, inversions, or large deletions or insertions are missed by most of the techniques, including direct DNA sequencing, but testing for these is commercially available. Such rearrangements are believed to be responsible for 12% to 18% of BRCA1 inactivating mutations but are less frequently seen in BRCA2 and in individuals of Ashkenazi Jewish (AJ) descent.[23-28]

Variants of uncertain significance

Germline deleterious mutations in the BRCA1/BRCA2 genes are associated with an approximately 60% lifetime risk of breast cancer and a 15% to 40% lifetime risk of ovarian cancer. There are no definitive functional tests for BRCA1 or BRCA2; therefore, the classification of nucleotide changes to predict their functional impact as deleterious or benign relies on imperfect data. The majority of accepted deleterious mutations result in protein truncation and/or loss of important functional domains. However, 10% to 15% of all individuals undergoing genetic testing with full sequencing of BRCA1 and BRCA2 will not have a clearly deleterious mutation detected but will have a variant of uncertain (or unknown) significance (VUS). VUS may cause substantial challenges in counseling, particularly in terms of cancer risk estimates and risk management. Clinical management of such patients needs to be highly individualized and must take into consideration factors such as the patient’s personal and family cancer history, in addition to sources of information to help characterize the VUS as benign or deleterious. Thus an improved classification and reporting system may be of clinical utility.[29]

A comprehensive analysis of 7,461 consecutive full gene sequence analyses performed by Myriad Genetic Laboratories, Inc. described the frequency of VUS over a 3-year period.[30] Among subjects who had no clearly deleterious mutation, 13% had VUS defined as “missense mutations and mutations that occur in analyzed intronic regions whose clinical significance has not yet been determined, chain-terminating mutations that truncate BRCA1 and BRCA2 distal to amino acid positions 1853 and 3308, respectively, and mutations that eliminate the normal stop codons for these proteins.” The classification of a sequence variant as a VUS is a moving target. An additional 6.8% of subjects with no clear deleterious mutations had sequence alterations that were once considered VUS but were reclassified as a polymorphism, or occasionally as a deleterious mutation.

The frequency of VUS varies by ethnicity within the U.S. population. African Americans appear to have the highest rate of VUS.[31] In a 2009 study of data from Myriad, 16.5% of individuals of African ancestry had VUS, the highest rate among all ethnicities. The frequency of VUS in Asian, Middle Eastern, and Hispanic populations clusters between 10% and 14%, although these numbers are based on limited sample sizes. Over time, the rate of changes classified as VUS has decreased in all ethnicities, largely the result of improved mutation classification algorithms.[32] VUS continue to be reclassified as additional information is curated and interpreted.[33,34] Such information may impact the continuing care of affected individuals.

A number of methods for discriminating deleterious from neutral VUS exist and others are in development [35-38] including integrated methods (see below).[39] Interpretation of VUS is greatly aided by efforts to track VUS in the family to determine if there is cosegregation of the VUS with the cancer in the family. In general, a VUS observed in individuals who also have a deleterious mutation, especially when the same VUS has been identified in conjunction with different deleterious mutations, is less likely to be in itself deleterious, although there are rare exceptions. As an adjunct to the clinical information, models to interpret VUS have been developed, based on sequence conservation, biochemical properties of amino acid changes,[35,40-44] incorporation of information on pathologic characteristics of BRCA1- and BRCA2-related tumors (e.g., BRCA1-related breast cancers are usually estrogen receptor [ER]–negative),[45] and functional studies to measure the influence of specific sequence variations on the activity of BRCA1 or BRCA2 proteins.[46,47] When attempting to interpret a VUS, all available information should be examined.

Population estimates of the likelihood of having a BRCA1 or BRCA2 mutation

Statistics regarding the percentage of individuals found to be BRCA mutation carriers among samples of women and men with a variety of personal cancer histories regardless of family history are provided below. These data can help determine who might best benefit from a referral for cancer genetic counseling and consideration of genetic testing but cannot replace a personalized risk assessment, which might indicate a higher or lower mutation likelihood based on additional personal and family history characteristics.

In some cases, the same mutation has been found in multiple apparently unrelated families. This observation is consistent with a founder effect, wherein a mutation identified in a contemporary population can be traced to a small group of founders isolated by geographic, cultural, or other factors. Most notably, two specific BRCA1 mutations (185delAG and 5382insC) and a BRCA2 mutation (6174delT) have been reported to be common in AJs. However, other founder mutations have been identified in African Americans and Hispanics.[48-50] The presence of these founder mutations has practical implications for genetic testing. Many laboratories offer directed testing specifically for ethnic-specific alleles. This greatly simplifies the technical aspects of the test but is not without limitations. For example, it is estimated that up to 15% of BRCA1 and BRCA2 mutations that occur among Ashkenazim are nonfounder mutations.[30]

Among the general population, the likelihood of having any BRCA mutation is as follows:

  • General population (excluding Ashkenazim): about 1 in 400 (~0.25%).[21,51]
  • Women with breast cancer (any age): 1 in 50 (2%).[52]
  • Women with breast cancer (younger than 40 years): 1 in 10 (10%).[53-55]
  • Men with breast cancer (any age): 1 in 20 (5%).[56]
  • Women with ovarian cancer (any age): 1 in 8 to 1 in 10 (10%–15%).[57-59]

Among AJ individuals, the likelihood of having any BRCA mutation is as follows:

  • General AJ population: 1 in 40 (2.5%).[60]
  • Women with breast cancer (any age): 1 in 10 (10%).[61]
  • Women with breast cancer (younger than 40 years): 1 in 3 (30%–35%).[61-63]
  • Men with breast cancer (any age): 1 in 5 (19%).[64]
  • Women with ovarian cancer or primary peritoneal cancer (all ages): 1 in 3 (36%–41%).[65-67]

Two large U.S. population-based studies of breast cancer patients younger than age 65 years examined the prevalence of BRCA1 [54,68] and BRCA2 [54] mutations in various ethnic groups. The prevalence of BRCA1 mutations in breast cancer patients by ethnic group was 3.5% in Hispanics, 1.3% to 1.4% in African Americans, 0.5% in Asian Americans, 2.2% to 2.9% in non-Ashkenazi whites, and 8.3% to 10.2% in Ashkenazi Jewish individuals.[54,68] The prevalence of BRCA2 mutations by ethnic group was 2.6% in African Americans and 2.1% in whites.[54]

A study of Hispanic patients with a personal or family history of breast cancer and/or ovarian cancer, who were enrolled through multiple clinics in the southwestern United States, examined the prevalence of BRCA1 and BRCA2 mutations. Deleterious BRCA mutations were identified in 189 of 746 patients (25%) (124 BRCA1, 65 BRCA2);[69] 21 of the 189 (11%) deleterious BRCA mutations identified were large rearrangements, of which 13 (62%) were BRCA1 ex9-12 deletions. In another population-based cohort of 492 Hispanic women with breast cancer, the BRCA1 ex9-12 deletion was found in three patients, suggesting that this mutation may be a Mexican founder mutation and may represent 10% to 12% of all BRCA1 mutations in similar clinic- and population-based cohorts in the United States. Within the clinic-based cohort, there were nine recurrent mutations, which accounted for 53% of all mutations observed in this cohort, suggesting the existence of additional founder mutations in this population.

A retrospective review of 29 AJ patients with primary fallopian tube tumors identified germline BRCA mutations in 17%.[67] Another study of 108 women with fallopian tube cancer identified mutations in 55.6% of the Jewish women and 26.4% of non-Jewish women (30.6% overall).[70] Estimates of the frequency of fallopian tube cancer in BRCA mutation carriers are limited by the lack of precision in the assignment of site of origin for high-grade, metastatic, serous carcinomas at initial presentation.[6,67,70,71]

Clinical criteria and models for prediction of the likelihood of a BRCA1 or BRCA2 mutation

Several studies have assessed the frequency of BRCA1 or BRCA2 mutations in women with breast or ovarian cancer.[54,55,68,72-80] Personal characteristics associated with an increased likelihood of a BRCA1 and/or BRCA2 mutation include the following:

  • Breast cancer diagnosed at an early age. (Some studies use age 40 years, while others use age 50 years as a cutoff.)
  • Ovarian cancer.
  • Bilateral breast cancer.
  • A history of both breast and ovarian cancer.
  • Breast cancer diagnosed in a male at any age.[72-75,78]
  • Triple-negative breast cancer diagnosed in women younger than 50 years.[81-83]
  • AJ background.[72,73,75]

Family history characteristics associated with an increased likelihood of carrying a BRCA1 and/or BRCA2 mutation include the following:

  • Multiple cases of breast cancer.
  • Both breast and ovarian cancer.
  • One or more breast cancers in male family members.
  • AJ background.[72-75]
Clinical criteria for identifying individuals who may have a BRCA1 or BRCA2 mutation

Several professional organizations and expert panels, including the American Society of Clinical Oncology,[84] the National Comprehensive Cancer Network (NCCN),[85] the American Society of Human Genetics,[86] the American College of Medical Genetics, the U.S. Preventive Services Task Force,[87] and the Society of Gynecologic Oncologists,[88] have developed clinical criteria that can be helpful to health care providers in identifying individuals who may have a BRCA1 or BRCA2 mutation.

Models for prediction of the likelihood of a BRCA1 or BRCA2 mutation

Many models have been developed to predict the probability of identifying germline BRCA1/BRCA2 mutations in individuals or families. These models include those using logistic regression,[30,72,73,75,78,89,90] genetic models using Bayesian analysis (BRCAPRO and Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm [BOADICEA]),[78,91] and empiric observations,[51,54,57,92-94] including the Myriad prevalence tables. More recently, using complex segregation analysis, a polygenetic model (BOADICEA) examining both breast cancer risk and the probability of having a BRCA1 or BRCA2 mutation has been published.[91] Even among experienced providers, the use of prediction models has been shown to increase the power to discriminate which patients are most likely to be identified as BRCA1/BRCA2 mutation carriers.[95,96] Most models do not include other cancers seen in the BRCA1 and BRCA2 spectrum such as pancreatic cancer and prostate cancer. Interventions that decrease the likelihood that an individual will develop cancer (such as oophorectomy and mastectomy) may influence the ability to predict BRCA1 and BRCA2 mutation status.[97] One study has shown that the risk models are sensitive to the amount of family history data available and do not perform as well with limited family information.[98]

The performance of the models can vary in specific ethnic groups. The BRCAPRO model appeared to best fit a series of French Canadian families.[99] There have been variable results in the performance of the BRCAPRO model among Hispanics,[100,101] and both the BRCAPRO model and Myriad tables underestimated the proportion of mutation carriers in an Asian American population.[102] Further information is needed to determine which model performs best in each ethnic group.

The power of several of the models has been compared in different studies.[103-106] Four breast cancer genetic risk models, BOADICEA, BRCAPRO, IBIS, and eCLAUS, were evaluated for their diagnostic accuracy in predicting BRCA1/2 mutations in a cohort of 7,352 German families.[107] The family member with the highest likelihood of carrying a mutation from each family was screened for BRCA1/2 mutations. Carrier probabilities from each model were calculated and compared with the actual mutations detected. BRCAPRO and BOADICEA had significantly higher diagnostic accuracy than IBIS or eCLAUS. Accuracy for the BOADICEA model was further improved when information on the tumor markers ER, progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2/neu) were included in the model.The inclusion of these biomarkers has been shown to improve the performance of BRCAPRO.[108,109]

Table 3. Characteristics of Common Models for Estimating the Likelihood of a BRCA1/2 Mutation
 Myriad Prevalence Tables [75] BRCAPRO [78,97] BOADICEA [78,91] Tyrer-Cuzick [110] 
AJ = Ashkenazi Jewish; BOADICEA = Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm; FDR = first-degree relatives; SDR = second-degree relatives.
Method Empiric data from Myriad Genetics based on family and personal history reported on requisition formsStatistical modelStatistical modelStatistical model
Features of the Model Proband may or may not have breast or ovarian cancerProband may or may not have breast or ovarian cancerProband may or may not have breast or ovarian cancerProband must be unaffected
Considers age of breast cancer diagnosis as <50 y, >50 yConsiders exact age at breast and ovarian cancer diagnosisConsiders exact age at breast and ovarian cancer diagnosisAlso includes reproductive factors and body mass index to estimate breast cancer risk
Considers breast cancer in ≥1 affected relative only if diagnosed <50 yConsiders prior genetic testing in family (i.e., BRCA1/BRCA2 mutation–negative relatives)Includes all FDR and SDR with and without cancer
Considers ovarian cancer in ≥1 relative at any ageConsiders oophorectomy statusIncludes AJ ancestry
Includes AJ ancestryIncludes all FDR and SDR with and without cancer
Very easy to useIncludes AJ ancestry
Limitations Simplified/limited consideration of family structureRequires computer software and time-consuming data entryRequires computer software and time-consuming data entryDesigned for individuals unaffected with breast cancer
Incorporates only FDR and SDR; may need to change proband to best capture risk and to account for disease in the paternal lineage
May overestimate risk in bilateral breast cancer [111]
Early age of breast cancer onsetMay perform better in whites than minority populations [101,112]Incorporates only FDR and SDR; may need to change proband to best capture risk
May underestimate risk of BRCA mutation in high-grade serous ovarian cancers but overestimate the risk for other histologies [113]

Genetic testing for BRCA1 and BRCA2 mutations has been available to the public since 1996. As more individuals have undergone testing, risk assessment models have improved. This, in turn, gives providers better data to estimate an individual patient’s risk of carrying a mutation, but risk assessment continues to be an art. There are factors that might limit the ability to provide an accurate risk assessment (i.e., small family size, paucity of women, or ethnicity) including the specific circumstances of the individual patient (such as history of disease or prophylactic surgeries).

Penetrance of mutations

The proportion of individuals carrying a mutation who will manifest the disease is referred to as penetrance. In general, common genetic variants that are associated with cancer susceptibility have a lower penetrance than rare genetic variants. This is depicted in Figure 3. For adult-onset diseases, penetrance is usually described by the individual carrier's age and sex. For example, the penetrance for breast cancer in female BRCA1/BRCA2 mutation carriers is often quoted by age 50 years and by age 70 years. Of the numerous methods for estimating penetrance, none are without potential biases, and determining an individual mutation carrier's risk of cancer involves some level of imprecision.

Enlarge
Graph shows relative risk on the x-axis and allele frequency on the y-axis. A line depicts the general finding of a low relative risk associated with common, low-penetrance genetic variants and a higher relative risk associated with rare, high-penetrance genetic variants.
Figure 3. Genetic architecture of cancer risk. This graph depicts the general finding of a low relative risk associated with common, low-penetrance genetic variants, such as single-nucleotide polymorphisms identified in genome-wide association studies, and a higher relative risk associated with rare, high-penetrance genetic variants, such as mutations in the BRCA1/ BRCA2 genes associated with hereditary breast and ovarian cancer and the mismatch repair genes associated with Lynch syndrome.

Numerous studies have estimated breast and ovarian cancer penetrance in BRCA1 and BRCA2 mutation carriers. Risk of both breast and ovarian cancer is consistently estimated to be higher in BRCA1 than in BRCA2 mutation carriers. Results from two large meta-analyses are shown in Table 4.[114,115] One study [114] analyzed pooled pedigree data from 22 studies involving 289 BRCA1 and 221 BRCA2 mutation–positive individuals. Index cases from these studies had female breast cancer, male breast cancer, or ovarian cancer but were unselected for family history. A subsequent study [115] combined penetrance estimates from the previous study and nine others that included an additional 734 BRCA1 and 400 BRCA2 mutation–positive families. The estimated cumulative risks of breast cancer by age 70 years in these two meta-analyses were 55% to 65% for BRCA1 and 45% to 47% for BRCA2 mutation carriers. Ovarian cancer risks were 39% for BRCA1 and 11% to 17% for BRCA2 mutation carriers.

Table 4. Estimated Cumulative Breast and Ovarian Cancer Risks in BRCA1 and BRCA2 Mutation Carriers
Study Breast cancer risk (%) by age 70 y (95% CI)  Ovarian cancer risk (%) by age 70 y (95% CI)  
CI = confidence interval.
BRCA1 BRCA2 BRCA1 BRCA2
Antoniou et al. (2003) [114]65 (44–78)45 (31–56)39 (18–54)11 (2.4–19)
Chen et al. (2007) [115]55 (50–59)47 (42–51)39 (34–45)17 (13–21)

While the cumulative risks of cancer by age 70 years are higher for BRCA1 than BRCA2 mutation carriers, the relative risks (RRs) of breast cancer decline with age more in BRCA1 mutation carriers.[114] Studies of penetrance for carriers of specific individual mutations are not usually large enough to provide stable estimates, but numerous studies of the Ashkenazi founder mutations have been conducted. One group of researchers analyzed the subset of families with one of the Ashkenazi founder mutations from their larger meta-analyses and found that the estimated penetrance for the individual mutations was very similar to the corresponding estimates among all mutation carriers.[116] A later study of 4,649 women with BRCA mutations reported significantly lower relative risks of breast cancer in those with the BRCA2 6174delT mutation than in those with other BRCA2 mutations (hazard ratio [HR], 0.35; confidence interval [CI], 0.18–0.69).[117]

One study provided prospective 10-year risks of developing cancer among asymptomatic carriers at various ages.[115] Nonetheless, making precise penetrance estimates in an individual carrier is difficult.

Risk-reducing salpingo-oophorectomy and/or use of oral contraceptives have been shown to alter risk.[61,114,118-123] (Refer to the Risk-reducing salpingo-oophorectomy section and the Oral contraceptives section of this summary for more information.) Other environmental factors being studied include reproductive and hormonal factors.[124-129] Genetic modifiers of penetrance of breast cancer and ovarian cancer are increasingly under study but are not clinically useful at this time.[130-132] (Refer to the Modifiers of Risk in BRCA1 and BRCA2 Mutation Carriers section for more information.) While the average breast cancer and ovarian cancer penetrances may not be as high as initially estimated, they are substantial, both in relative and absolute terms, particularly in women born after 1940. A higher risk before age 50 years has been consistently seen in more recent birth cohorts,[61,133] and additional studies will be required to further characterize potential modifying factors to arrive at more precise individual risk projections. Precise penetrance estimates for less common cancers, such as pancreatic cancer, are lacking.

Cancers other than female breast/ovarian

Female breast and ovarian cancers are clearly the dominant cancers associated with BRCA1 and BRCA2. BRCA mutations also confer an increased risk of fallopian tube and primary peritoneal carcinomas. One large study from a familial registry of BRCA1 mutation carriers has found a 120-fold RR of tubal cancer among BRCA1 mutation carriers compared with the general population.[6] The risk of primary peritoneal cancer among BRCA mutation carriers with intact ovaries is increased but remains poorly quantified, despite a residual risk of 3% to 4% in the 20 years after risk-reducing salpingo-oophorectomy.[134,135] (Refer to the Risk-reducing salpingo-oophorectomy section in the Ovarian cancer section of this summary for more information.)

Pancreatic, male breast, and prostate cancers have also been consistently associated with BRCA mutations, particularly with BRCA2. Other cancers have been associated in some studies. The strength of the association of these cancers with BRCA mutations has been more difficult to estimate because of the lower numbers of these cancers observed in mutation carriers.

Men with BRCA2 mutations, and to a lesser extent BRCA1 mutations, are at increased risk of breast cancer with lifetime risks estimated at 5% to 10% and 1% to 2%, respectively.[6,8,9,136] Men carrying BRCA2 mutations, and to a lesser extent BRCA1 mutations, have an approximately threefold to sevenfold increased risk of prostate cancer.[7,8,12,94,137-139] BRCA2-associated prostate cancer also appears to be more aggressive.[140-145] (Refer to the BRCA1 and BRCA2 section in the PDQ summary on Genetics of Prostate Cancer for more information.)

Studies of familial pancreatic cancer (FPC) [146-150] and unselected series of pancreatic cancer [151-153] have also supported an association with BRCA2, and to a lesser extent, BRCA1.[7] Overall, it appears that between 3% to 15% of families with FPC may have germline BRCA2 mutations, with risks increasing with more affected relatives.[146-148] Similarly, studies of unselected pancreatic cancers have reported BRCA2 mutation frequencies between 3% to 7%, with these numbers approaching 10% in those of AJ descent.[151,152,154] The lifetime risk of pancreatic cancer in BRCA2 carriers is estimated to be 3% to 5%,[8,12] compared with an estimated lifetime risk of 0.5% by age 70 years in the general population.[155] Other cancers associated with BRCA2 mutations in some, but not all, studies include melanoma, biliary cancers, and head and neck cancers, but these risks appear modest (<5% lifetime) and are less well studied.[12]

Table 5. Spectrum of Cancers in BRCA1 and BRCA2 Mutation Carriers
Cancer Sites [6-8,12,60,139] BRCA1 Mutation Carrier BRCA2 Mutation Carrier 
Strength of Evidence Magnitude of Absolute Risk Strength of Evidence Magnitude of Absolute Risk
Breast (female)+++High+++High
Ovary, fallopian tube, peritoneum+++High+++Moderate
Breast (male)+Undefined+++Low
Pancreas++Very Low+++Low
Prostatea+Undefined+++High

aRefer to the PDQ summary on Genetics of Prostate Cancer for more information about the association of BRCA1 and BRCA2 with prostate cancer.
+++ Multiple studies demonstrated association and are relatively consistent.
++ Multiple studies and the predominance of the evidence are positive.
+ May be an association, predominantly single studies; smaller limited studies and/or inconsistent but weighted toward positive.

The first Breast Cancer Linkage Consortium study investigating cancer risks reported an excess of colorectal cancer in BRCA1 carriers (RR, 4.1; 95% CI, 2.4–7.2).[156] This finding was supported by some,[6,7,157] but not all,[8,60,66,94,158-160] family-based studies. However, unselected series of colorectal cancer that have been exclusively performed in the AJ population have not shown elevated rates of BRCA1 or BRCA2 mutations.[161-163] Taken together, the data suggest little, if any, increased risk of colorectal cancer, and possibly only in specific population groups. Therefore, at this time, BRCA1 mutation carriers should adhere to population-screening recommendations for colorectal cancer.

No increased prevalence of hereditary BRCA mutations was found among 200 Jewish women with endometrial carcinoma or 56 unselected women with uterine papillary serous carcinoma.[164,165] (Refer to the Risk-reducing salpingo-oophorectomy section in the Ovarian cancer section of this summary for more information.)

Cancer risk in individuals who test negative for a known familial BRCA1/BRCA2 mutation ("true negative")

There is conflicting evidence as to the residual familial risk among women who test negative for the BRCA1/BRCA2 mutation segregating in the family. An initial study based on prospective evaluation of 353 women who tested negative for the BRCA1 mutation segregating in the family found that five incident breast cancers occurred during more than 6,000 person-years of observation, for a lifetime risk of 6.8%, a rate similar to the general population.[121] A report that the risk may be as high as fivefold in women who tested negative for the BRCA1 or BRCA2 mutation in the family [166] was followed by numerous letters to the editor suggesting that ascertainment biases account for much of this observed excess risk.[167-172] Three additional analyses have suggested an approximate 1.5-fold to 2-fold excess risk.[171,173,174] Several studies have involved retrospective analyses; all studies have been based on small observed numbers of cases and have been of uncertain statistical and clinical significance. No cases of ovarian cancer have been reported in these studies.[171]

Results from numerous other prospective studies have found no increased risk. A study of 375 women who tested negative for a known familial mutation in BRCA1 or BRCA2 reported two invasive breast cancers, two in situ breast cancers, and no ovarian cancers diagnosed, with a mean follow-up of 4.9 years. Four invasive breast cancers were expected, whereas two were observed.[175] Another study of similar size but longer follow-up (395 women and 7,008 person-years of follow-up) also found no statistically significant overall increase in breast cancer risk among mutation-negative women (observed/expected [O/E], 0.82; 95% CI, 0.39–1.51), although women who had at least one first-degree relative with breast cancer had a nonsignificant increased risk (O/E, 1.33; 95% CI, 0.41–2.91).[176] A study of 160 BRCA1 and 132 BRCA2 mutation–positive families from the Breast Cancer Family Registry found no evidence for increased risk among noncarriers in these families.[177] In a large study of 722 mutation-negative women from Australia in whom six invasive breast cancers were observed after a median follow-up of 6.3 years, the standardized incidence ratio (SIR) was not significantly elevated (SIR, 1.14; 95% CI, 0.51–2.53).[178] Based on available data, it appears that women testing negative for known familial BRCA1/BRCA2 mutations can adhere to general population screening guidelines unless they have sufficient additional risk factors, such as a personal history of atypical hyperplasia of the breast or family history of breast cancer in relatives who do not carry the familial mutation.

Breast and ovarian cancer risk in breast cancer families without detectable BRCA1/BRCA2 mutations ("indeterminate")

The majority of families with site-specific breast cancer test negative for BRCA1/BRCA2 and have no features consistent with Cowden syndrome or Li-Fraumeni syndrome.[30] Five studies using population-based and clinic-based approaches have demonstrated no increased risk of ovarian cancer in such families. Although ovarian cancer risk was not increased, breast cancer risk remained elevated.[177,179,179,180,180,181,181-183]

Modifiers of Risk in BRCA1 and BRCA2 Mutation Carriers

Deleterious mutations in BRCA1 and BRCA2 confer high risks of breast and ovarian cancers. The risks, however, are not equal in all mutation carriers and have been found to vary by several factors, including type of cancer, age at onset, and mutation position.[184] This observed variation in penetrance has led to the hypothesis that other genetic and/or environmental factors modify cancer risk in mutation carriers. There is a growing body of literature identifying genetic and nongenetic factors that contribute to the observed variation in rates of cancers seen in families with BRCA1/2 mutations.

Genetic Modifiers of Breast and Ovarian Cancer Risk

The largest studies investigating genetic modifiers of breast and ovarian cancer risk to date have come from the Consortium of Investigators of Modifiers of BRCA1 and BRCA2 (CIMBA), a large international effort with genotypic and phenotypic data on more than 15,000 BRCA1 and 10,000 BRCA2 carriers.[185] Using candidate gene analysis and genome-wide association studies, CIMBA has identified several loci associated both with increased and decreased risk of breast cancer and ovarian cancer. Some of the single nucleotide polymorphisms (SNPs) are related to subtypes of breast cancer, such as hormone-receptor and HER2/neu status. The risks conferred are all modest but if operating in a multiplicative fashion could significantly impact risk of cancer in BRCA1/2 mutation carriers. Currently, these SNPs are not being tested for or used in clinical decision making.

Table 6. Genetic Modifiers of Breast Cancer Risk
Putative Gene  Chromosome SNP Citation OR (95% CI) Comments 
CI = confidence interval; ER+ = estrogen receptor–positive; ER- = estrogen receptor–negative; OR = odds ratio, SNP = single nucleotide polymorphism.
EMBP1 1p11.2rs11249433[186]1.09 (1.02–1.17)BRCA2 carriers
MDM4 1q32.1rs2290854[187]1.14 (1.09–1.20)BRCA1 carriers
CYP1BI-AS1 2p22.2rs184577[188]0.85 (0.79–0.91)BRCA2 carriers
CASP8 2q33D302H variant[189]0.85 (0.76–0.97)BRCA1 carriers
SLC4A/NEKID 3p24.1rs4973768[130]1.10 (1.03–1.18)BRCA2 carriers
MAP3K1 5q11.2rs889312[130]1.10 (1.01–1.19)BRCA2 carriers
FGF10/MRPS30 5p12rs10941679[130]1.09 (1.01–1.19)BRCA2 carriers
TERT 5p15.33rs2736108[190]0.92 (0.88–0.96)BRCA1 carriers
5p15.33rs10069690[190]1.16 (1.11–1.21)BRCA1 carriers
6q22.23rs218341[191]0.89 (0.80–1.00)BRCA1 carriers
6p24rs9348512[188]0.85 (0.80–0.90)BRCA2 carriers
ESR1 6q25.1rs2046210[186]1.17 (1.11–1.23)BRCA1 carriers
6q25.1rs9397435[186]1.28 (1.18–1.40)BRCA1 carriers
6q25.1rs9397435[186]1.14 (1.01–1.28)BRCA2 carriers
LRRC4C 9q31.2rs965686[192]0.95 (0.89–1.01)BRCA2 carriers
ZNF365 10q21.1rs10995190[192]0.90 (0.82–0.98)BRCA2 carriers
10q21.2rs16917302[193]0.84 (0.72–0.97)BRCA1 carriers, mainly ER+
10q21.2rs16917302[194]0.75 (0.60–0.86)BRCA2 carriers
FGFR2 10q26.13rs2981582[130,195]1.30 (1.20–1.40)BRCA2 carriers
10q26.13rs2981582[130,195]1.35 (1.17–1.56)BRCA1 carriers, ER+
10q26.13rs2981582[130,195]0.91 (0.85–0.98)BRCA1 carriers, ER-
LSP1 11p15.5rs3817198[130]1.14 (1.06–1.23)BRCA2 carriers
PTHLH 12p11rs10771399[192]0.87 (0.81–0.94)BRCA1 carriers
RAD51 15q15.1rs1801320[196]3.18 (1.39–7.27)BRCA2 carriers (CC homozygous only)
TOX3/TNRC9 16q12.1rs3803662[130]1.09 (1.03–1.16)BRCA1 carriers
16q12.1rs3803662[130]1.17 (1.07–1.27)BRCA2 carriers
BRCA1-wild type17prs16942[197]0.86 (0.77–0.95)Wild type modifies BRCA1
BABAM1 19p13.11rs8170[198]1.25 (1.18–1.33)BRCA1 carriers, triple negative
19p13.11rs865686[192]0.86 (0.78–0.95)BRCA2 carriers
19p13.11rs67397200[193]1.17 (1.11–1.23)BRCA1 carriers, mainly ER-
GMEB2 20q13.3rs311499[194]0.72 (0.61–0.85)BRCA2 carriers
FGF13 Xq27.1rs619373[188]1.30 (1.16–3.41)BRCA2 carriers

Table 7. Genetic Modifiers of Ovarian Cancer Risk
Putative Gene Chromosome SNP Citation OR (95% CI) Comments 
CI = confidence interval; OR = odds ratio, SNP = single nucleotide polymorphism.
HOXD3 2q31rs717852[199]1.25 (1.10-1.42)BRCA2 carriers
CASP8 2q33D302H variant[189]0.69 (0.53–0.89)BRCA1 carriers
IRS1 2q36.3rs1801278[200]1.43 (1.06–1.92)BRCA1 carriers
2q36.3rs1801278[200]2.21 (1.39–3.52)BRCA2 carriers
2q36.3rs13306465[200]2.42 (1.06–5.56)BRCA1 carriers, type II mutations only
TIPARP 3q25.31rs2665390[199]1.48 (1.21–1.83)BRCA2 carriers
3q25.31rs2665390[199]1.25 (1.10–1.43)BRCA1 carriers
4q32.3rs4691139[187]1.20 (1.17–1.38)BRCA1 carriers
8q24rs10088218[199]0.81 (0.67–0.98)BRCA2 carriers
8q24rs10088218[199]0.89 (0.81–0.99)BRCA1 carriers
BCN2/CNTLN 9p22.2rs3814113[131]0.78 (0.72–0.85)BRCA1 carriers
9p22.2rs3814113[131]0.78 (0.67–0.90)BRCA2 carriers
10p13.1rs8170[193]1.15 (1.03–1.30)BRCA1 carriers
10p13.1rs8170[193]1.34 (1.12–1.62)BRCA2 carriers
10p13.1rs8170[193]0.78 (0.67–0.90)BRCA2 carriers
PLEKHM1 17q21.31rs17631303[187]1.27 (1.17–1.38)BRCA1 carriers
17q21.31rs17631303[187]1.32 (1.15–1.52)BRCA2 carriers
SKAP1 17q21.32rs9303542[199]1.16 (1.02–1.33)BRCA2 carriers
CERS6 19p13.1rs6739200[193]1.16 (1.05–1.29)BRCA1carriers
19p13.1rs6739200[193]1.30 (1.10–1.52)BRCA2 carriers

Role of BRCA1 and BRCA2 in sporadic cancer

Given that germline mutations in BRCA1 or BRCA2 lead to a very high probability of developing breast and/or ovarian cancer, it was a natural assumption that these genes would also be involved in the development of the more common nonhereditary forms of the disease. Although somatic mutations in BRCA1 and BRCA2 are not common in sporadic breast and ovarian cancer tumors,[201-204] there is increasing evidence that downregulation of BRCA1 protein expression may play a role in these tumor types. Compared with normal breast epithelium, many breast cancers have low levels of the BRCA1 mRNA, which may result from hypermethylation of the gene promoter.[205-207] Similar findings have not been reported for BRCA2 mutations, although the BRCA2 locus on chromosome 13q is the target of frequent loss of heterozygosity (LOH) in breast cancer.[208,209] Approximately 10% to 15% of sporadic breast cancers appear to have BRCA1 promoter hypermethylation, and even more have downregulation of BRCA1 by other mechanisms. Basal-type breast cancers (ER-negative, PR-negative, HER2-negative, and cytokeratin 5/6–positive) more commonly have BRCA1 dysregulation than other tumor types.[210-212] BRCA1-related tumor characteristics have also been associated with constitutional methylation of the BRCA1 promoter. In a study of 255 breast cancers diagnosed before age 40 years in women without germline BRCA1 mutations, methylation of BRCA1 in peripheral blood was observed in 31% of women whose tumors had multiple BRCA1-associated pathological characteristics (e.g., high mitotic index and growth pattern including multinucleated cells) compared with less than 4% methylation in controls.[213] (Refer to the BRCA1 pathology section for more information.) Loss of BRCA1 or BRCA2 protein expression is more common in ovarian cancer than in breast cancer,[214] and downregulation of BRCA1 is associated with enhanced sensitivity to cisplatin and improved survival in this disease.[215,216] Targeted therapies are being developed for tumors with loss of BRCA1 or BRCA2 protein expression.[217]

Genotype-phenotype correlations

Some genotype-phenotype correlations have been identified in both BRCA1 and BRCA2 mutation families. None of the studies have had sufficient numbers of mutation-positive individuals to make definitive conclusions, and the findings are probably not sufficiently established to use in individual risk assessment and management. In 25 families with BRCA2 mutations, an ovarian cancer cluster region was identified in exon 11 bordered by nucleotides 3,035 and 6,629.[11,218] This is the region of the gene containing the BRCA1 C-terminal repeat,[219] which has been shown to specifically interact with RAD51. A study of 164 families with BRCA2 mutations collected by the Breast Cancer Linkage Consortium confirmed the initial finding. Mutations within the ovarian cancer cluster region were associated with an increased risk of ovarian cancer and a decreased risk of breast cancer in comparison with families with mutations on either side of this region.[220] In addition, a study of 356 families with protein-truncating BRCA1 mutations collected by the Breast Cancer Linkage Consortium reported breast cancer risk to be lower with mutations in the central region (nucleotides 2,401–4,190) compared with surrounding regions. Ovarian cancer risk was significantly reduced with mutations 3’ to nucleotide 4,191.[221] These observations have generally been confirmed in subsequent studies.[114,222,223] Studies in Ashkenazim, in whom substantial numbers of families with the same mutation can be studied, have also found higher rates of ovarian cancer in carriers of the BRCA1:185delAG mutation, in the 5' end of BRCA1, compared with carriers of the BRCA1:5382insC mutation in the 3' end of the gene.[224,225] The risk of breast cancer, particularly bilateral breast cancer, and the occurrence of both breast and ovarian cancer in the same individual, however, appear to be higher in BRCA1:5382insC mutation carriers compared with carriers of BRCA1:185delAG and BRCA2:6174delT mutations. Ovarian cancer risk is considerably higher in BRCA1 mutation carriers, and it is uncommon before age 45 years in BRCA2:6174delT mutation carriers.[224,225]

Pathology of breast cancer

BRCA1 pathology

Several studies evaluating pathologic patterns seen in BRCA1-associated breast cancers have suggested an association with adverse pathologic and biologic features. These findings include higher than expected frequencies of medullary histology, high histologic grade, areas of necrosis, trabecular growth pattern, aneuploidy, high S-phase fraction, high mitotic index, and frequent TP53 mutations.[226-233] In a large international series of 3,797 BRCA1 mutation carriers, the median age at breast cancer diagnosis was 40 years.[233] Of breast tumors arising in BRCA1 carriers, 78% were ER-negative; 79% were PR-negative; 90% were HER2-negative; and 69% were triple-negative. These findings were consistent with multiple smaller series.[81,229,234-236] In addition, the proportion of ER-negative tumors significantly decreased as the age at breast cancer diagnosis increased.[233]

There is considerable, but not complete, overlap between the triple-negative and basal-like subtype cancers, both of which are common in BRCA1-associated breast cancer,[237,238] particularly in women diagnosed before age 50 years.[81-83] A small proportion of BRCA1-related breast cancers are ER-positive, which are associated with later age of onset.[239,240] These ER-positive cancers have clinical behavior features that are "intermediate" between ER-negative BRCA1 cancers and ER-positive sporadic breast cancers, raising the possibility that there may be a unique mechanism by which they develop.

The prevalence of germline BRCA1 mutations in women with triple-negative breast cancer is significant, both in women undergoing clinical genetic testing (and thus selected in large part for family history) and in unselected triple-negative patients, with mutations reported in 9% to 35%.[83,229,234,241-247] The highest rate reported was in a clinic-based series in women younger than 30 years with high-grade triple-negative breast cancer. In this small, highly selected population, 35% had BRCA1 mutations. Notably, studies have demonstrated a high rate of BRCA1 mutations in unselected women with triple-negative breast cancer, particularly in those diagnosed before age 50 years. One study examined 308 individuals with triple-negative breast cancer; BRCA1 mutations were present in 45. Mutations were seen both in women unselected for family history (11 of 58; 19%) and in those with family history (26 of 111; 23%).[248] A group of researchers reported results of BRCA1/2 testing in 77 unselected patients with triple-negative breast cancer. Of these, 15 (19.5%) had either a germline BRCA1 (n = 11; 14%) or BRCA2 (n = 3; 4%) mutation or a somatic BRCA1 (n = 1) mutation. The median age at cancer diagnosis was 45 years in BRCA1 mutation carriers and 53 years in noncarriers (P = .005). Interestingly, this study also demonstrated a lower risk of relapse in those with BRCA1 mutation–associated triple-negative breast cancer than in those with nonmutated triple-negative breast cancer, although this study was limited by its size.[244] A second study examining clinical outcomes in BRCA1-associated versus non-BRCA1-associated triple-negative breast cancer showed no difference, although there was a trend toward more brain metastases in those with BRCA1-associated breast cancer. In both of these studies, all but one BRCA1 mutation carrier received chemotherapy.[245] A subsequent study of 199 patients with triple-negative breast cancer recruited through a community oncology practice identified 21 BRCA mutations (10.6%), of which 13 were in BRCA1 and 8 were in BRCA2.[249] In another unselected sample, BRCA1 mutations were detected in 16 of 182 women (9%) with triple-negative breast cancer who were aged 26 to 69 years at diagnosis.[247] Five of the 16 women were diagnosed at a later age and/or lacked additional risk factors such as significant family histories.

It has been hypothesized that many BRCA1 tumors are derived from the basal epithelial layer of cells of the normal mammary gland, which account for 3% to 15% of unselected invasive ductal cancers. If the basal epithelial cells of the breast represent the breast stem cells, the regulatory role suggested for wild-type BRCA1 may partly explain the aggressive phenotype of BRCA1-associated breast cancer when BRCA1 function is damaged.[250] Further studies are needed to fully appreciate the significance of this subtype of breast cancer within the hereditary syndromes.

The most accurate method for identifying basal-like breast cancers is through gene expression studies, which have been used to classify breast cancers into biologically- and clinically-meaningful groups.[235,251,252] This technology has also been shown to correctly differentiate BRCA1- and BRCA2-associated tumors from sporadic tumors in a high proportion of cases.[253-255] Notably, among a set of breast tumors studied by gene expression array to determine molecular phenotype, all tumors with BRCA1 alterations fell within the basal tumor subtype;[235] however, this technology is not in routine use due to its high cost. Instead, immunohistochemical markers of basal epithelium have been proposed to identify basal-like breast cancers, which are typically negative for ER, progesterone receptor, and HER2, and stain positive for cytokeratin 5/6, or epidermal growth factor receptor.[256-259] Based on these methods to measure protein expression, a number of studies have shown that the majority of BRCA1-associated breast cancers are positive for basal epithelial markers.[81,229,258]

There is growing evidence that preinvasive lesions are a component of the BRCA phenotype. The Breast Cancer Linkage Consortium initially reported a relative lack of an in situ component in BRCA1-associated breast cancers,[227] also seen in two subsequent studies of BRCA1/BRCA2 carriers.[260,261] However, in a study of 369 ductal carcinoma in situ (DCIS) cases, BRCA1 and BRCA2 mutations were detected in 0.8% and 2.4%, respectively, which is only slightly lower than previously reported prevalence in studies of invasive breast cancer patients.[262] A retrospective study of breast cancer cases in a high-risk clinic found similar rates of preinvasive lesions, particularly DCIS, among 73 BRCA-associated breast cancers and 146 mutation-negative cases.[263,264] A study of AJ women, stratified by whether they were referred to a high-risk clinic or were unselected, showed similar prevalence of DCIS and invasive breast cancers in referred patients compared with one-third lower DCIS cases among unselected subjects.[265] Similarly, data about the prevalence of hyperplastic lesions have been inconsistent, with reports of increased [266,267] and decreased prevalence.[261] Similar to invasive breast cancer, DCIS diagnosed at an early age and/or with a family history of breast and/or ovarian cancer is more likely to be associated with a BRCA1/BRCA2 mutation.[268]

Overall evidence suggests DCIS is part of the BRCA1/BRCA2 spectrum, particularly BRCA2; however, the prevalence of mutations in DCIS patients, unselected for family history, is less than 5%.[262,265]

BRCA2 pathology

The phenotype for BRCA2-related tumors appears to be more heterogeneous and is less well-characterized than that of BRCA1, although they are generally positive for ER and PR.[227,269,270] A large international series of 2,392 BRCA2 mutation carriers found that only 23% of tumors arising in BRCA2 mutation carriers were ER-negative; 36% were PR-negative; 87% were HER2-negative; and 16% were triple-negative.[233] A report from Iceland found less tubule formation, more nuclear pleomorphism, and higher mitotic rates in BRCA2-related tumors than in sporadic controls; however, a single BRCA2 founder mutation (999del5) accounts for nearly all hereditary breast cancer in this population, thus limiting the generalizability of this observation.[271] A large case series from North America and Europe described a greater proportion of BRCA2-associated tumors with continuous pushing margins (a histopathologic description of a pattern of invasion), fewer tubules and lower mitotic counts.[272] Other reports suggest that BRCA2-related tumors include an excess of lobular and tubulolobular histology.[228,269] In summary, histologic characteristics associated with BRCA2 mutations have been inconsistent.

Pathology of ovarian cancer

Ovarian cancers in women with BRCA1 and BRCA2 mutations are more likely to be high-grade serous adenocarcinomas and are less likely to be mucinous or borderline tumors.[273-277] Fallopian tube cancer and peritoneal carcinomas are also part of the BRCA-associated disease spectrum.[67,278]

Histopathologic examinations of fallopian tubes removed from women with a hereditary predisposition to ovarian cancer show dysplastic and hyperplastic lesions that suggest a premalignant phenotype.[279,280] Occult carcinomas have been reported in 2% to 11% of adnexa removed from BRCA mutation carriers at the time of risk-reducing surgery.[281-283] Most of these occult lesions are seen in the fallopian tubes, which has led to the hypothesis that many BRCA-associated ovarian cancers may actually have originated in the fallopian tubes. Specifically, the distal segment of the fallopian tubes (containing the fimbriae) has been implicated as a common origin of the high-grade serous cancers seen in BRCA mutation carriers, based on the close proximity of the fimbriae to the ovarian surface, exposure of the fimbriae to the peritoneal cavity, and the broad surface area in the fimbriae.[284] Because of the multicentric origin of high-grade serous carcinomas from Müllerian-derived tissue, staging of ovarian, tubal, and peritoneal carcinomas is now considered collectively by the International Federation of Gynecology and Obstetrics. The term “high-grade serous ovarian carcinoma” may be used to represent high-grade pelvic serous carcinoma for consistency in language.[285]

High-grade serous ovarian carcinomas have a higher incidence of somatic TP53 mutations.[273,286] DNA microarray technology suggests distinct molecular pathways of carcinogenesis between BRCA1, BRCA2, and sporadic ovarian cancer.[287] Furthermore, data suggest that BRCA-related ovarian cancers metastasize more frequently to the viscera, while sporadic ovarian cancers remain confined to the peritoneum.[288]

Unlike high-grade serous carcinomas, low-grade serous ovarian cancer is not likely to be part of the BRCA1/BRCA2 spectrum.[289]

Clinical management of BRCA mutation carriers

Increasing data are available on the outcomes of interventions to reduce risk in people with a genetic susceptibility to breast cancer or ovarian cancer.[84,85,87,290,291] As outlined in other sections of this summary, uncertainty is often considerable regarding the level of cancer risk associated with a positive family history or genetic test. In this setting, personal preferences are likely to be an important factor in patients’ decisions about risk reduction strategies.

Screening and Prevention Strategies

Breast cancer

Screening/surveillance

Refer to the PDQ summary on Breast Cancer Screening for information on screening in the general population, and to the PDQ summary Levels of Evidence for Cancer Genetics Studies for information on levels of evidence related to screening and prevention.

Breast self-examination

In the general population, evidence for the value of breast self-examination (BSE) is limited. Preliminary results have been reported from a randomized study of BSE being conducted in Shanghai, China.[292] At 5 years, no reduction in breast cancer mortality was seen in the BSE group compared with the control group of women, nor was a substantive stage shift seen in breast cancers that were diagnosed. (Refer to the PDQ summary on Breast Cancer Screening for more information.)

Little direct prospective evidence exists regarding BSE in individuals with an increased risk of breast cancer. In the Canadian National Breast Screening Study, women with first-degree relatives with breast cancer had statistically significantly higher BSE competency scores than those without a family history. In a study of 251 high-risk women at a referral center, five breast cancers were detected by self-examination less than a year after a previous screen (as compared with one cancer detected by clinician exam and 11 cancers detected as a result of mammography). Women in the cohort were instructed in self-examination, but it is not stated whether the interval cancers were detected as a result of planned self-examination or incidental discovery of breast masses.[293] In another series of BRCA1/BRCA2 mutation carriers, four of nine incident cancers were diagnosed as palpable masses after a reportedly normal mammogram, further suggesting the potential value of self-examination.[294] A task force convened by the Cancer Genetics Studies Consortium has recommended “monthly self-examination beginning early in adult life (e.g., by age 18–21 years) to establish a regular habit and allow familiarity with the normal characteristics of breast tissue. Education and instruction in self-examination are recommended.”[295]

Level of evidence: 5

Clinical breast examination

Few prospective data exist regarding clinical breast examination (CBE).

The Cancer Genetics Studies Consortium task force concluded, “As with self-examination, the contribution of clinical examination may be particularly important for women at inherited risk of early breast cancer.” They recommended that female carriers of a BRCA1 or BRCA2 high-risk mutation undergo annual or semiannual clinical examinations beginning at age 25 to 35 years.[295]

Mammography

In the general population, strong evidence suggests that regular mammography screening of women aged 50 to 59 years leads to a 25% to 30% reduction in breast cancer mortality. (Refer to the PDQ summary on Breast Cancer Screening for more information.) For women who begin mammographic screening at age 40 to 49 years, a 17% reduction in breast cancer mortality is seen, which occurs 15 years after the start of screening.[296] Observational data from a cohort study of more than 28,000 women suggest that the sensitivity of mammography is lower for young women. In this study, the sensitivity was lowest for younger women (aged 30–49 years) who had a first-degree relative with breast cancer. For these women, mammography detected 69% of breast cancers diagnosed within 13 months of the first screening mammography. By contrast, sensitivity for women younger than 50 years without a family history was 88% (P = .08). For women aged 50 years and older, sensitivity was 93% at 13 months and did not vary by family history.[297] Preliminary data suggest that mammography sensitivity is lower in BRCA1 and BRCA2 carriers than in noncarriers.[294] Subsequent observational studies have found that the positive predictive value (PPV) of mammography increases with age and is highest among older women and among women with a family history of breast cancer.[298] Higher PPVs may be due to increased breast cancer incidence, higher sensitivity, and/or higher specificity.[299] One study found an association between the presence of pushing margins and false-negative mammograms in 28 women, 26 of whom had a BRCA1 mutation and two of whom had a BRCA2 mutation. Pushing margins, characteristic of medullary histology, are associated with an absence of fibrotic reaction.[300] In addition, rapid tumor doubling times may lead to tumors presenting shortly after an apparently normal study. In one study, mean tumor doubling time in BRCA1/BRCA2 carriers was 45 days, compared with 84 days in noncarriers.[301] Another study that evaluated mammographic breast density in women with BRCA mutations found no association between mutation status and mammographic density; however, in both carriers and noncarriers, increased breast density was associated with increased breast cancer risk.[302]

The randomized Canadian National Breast Screening Study-2 compared annual CBE plus mammography to CBE alone in women aged 50 to 59 years from the general population. Both groups were given instruction in BSE.[303] Although mammography detected smaller primary invasive tumors, more invasive cancers, and more DCIS than CBE, the breast cancer mortality rates in the CBE-plus-mammography group and the CBE-alone group were nearly identical, and compared favorably with other breast cancer screening trials. After a mean follow-up of 13 years (range 11.3–16.0 years), the cumulative breast cancer mortality ratio was 1.02 (95% CI = 0.78–1.33). One possible explanation of this finding was the careful training and supervision of the health professionals performing CBE.

Digital mammography refers to the use of a digital detector to find and record x-ray images. This technology improves contrast resolution [304] and has been proposed as a potential strategy for improving the sensitivity of mammography. A screening study comparing digital with routine mammography in 6,736 examinations of women aged 40 years and older found no difference in cancer detection rates;[305] however, digital mammography resulted in fewer recalls. In another study (ACRIN-6652) comparing digital mammography to plain-film mammography in 42,760 women, the overall diagnostic accuracy of the two techniques was similar.[306] When receiver operating characteristic curves were compared, digital mammography was more accurate in women younger than 50 years, in women with radiographically dense breasts, and in premenopausal or perimenopausal women.

In a prospective study of 251 individuals with BRCA mutations who received uniform recommendations regarding screening and risk-reducing, or prophylactic, surgery, annual mammography detected breast cancer in six women at a mean of 20.2 months after receipt of BRCA results.[293] The Cancer Genetics Studies Consortium task force has recommended for female carriers of a BRCA1 or BRCA2 high-risk mutation, “annual mammography, beginning at age 25 to 35 years. Mammograms should be done at a consistent location when possible, with prior films available for comparison.”[295] Data from prospective studies on the relative benefits and risks of screening with an ionizing radiation tool versus CBE or other nonionizing radiation tools would be useful.[307-309]

Certain observations have led to the concern that BRCA mutation carriers may be more prone to radiation-induced breast cancer than women without mutations. The BRCA1 and BRCA2 proteins are known to be important in cellular mechanisms of DNA damage repair, including those involved in repairing radiation-induced damage. Some studies have suggested intermediate radiation sensitivity in cells that are heterozygous for a BRCA mutation, but this is not consistent and varies by experimental system and endpoint.

Two studies failed to find convincing evidence of an association between ionizing radiation exposure and breast cancer risk in BRCA1 and BRCA2 mutation carriers.[310,311] In contrast, two large international studies found evidence of an increased breast cancer risk due to chest x-rays [312] or estimates of total exposure to diagnostic radiation.[313] A large, international, case-control study of 1,601 mutation carriers described an increased risk of breast cancer (HR, 1.54) among women who were ever exposed to chest x-rays, with risk being highest in women aged 40 years and younger, born after 1949, and exposed to x-rays only before age 20 years.[312] Some of the subjects in this study were also included in a larger, more comprehensive analysis of mutation carriers from three European centers.[313] In that study of 1,993 BRCA1 and BRCA2 mutation carriers from the United Kingdom, France, and the Netherlands, age-specific total diagnostic radiation exposure (e.g., chest x-rays, mammography, fluoroscopy, and computed tomography) estimates were derived from self-reported questionnaires. Women exposed before age 30 years had an increased risk (HR, 1.90; 95%, CI 1.20–3.00), compared with those never exposed. This risk was primarily driven by nonmammographic radiation exposure in women younger than age 20 years (HR, 1.62; 95% CI, 1.02–2.58).

With the routine use of magnetic resonance imaging (MRI) in BRCA1 and BRCA2 mutation carriers, any potential benefit of mammographic screening must be carefully weighed against potential risks, particularly in young women.[314] One study has suggested that the most cost-effective screening strategy in BRCA1 and BRCA2 mutation carriers may be annual MRI beginning at age 25 years, with alternating MRI and digital mammography (so that each test is done annually but screening occurs every 6 months) beginning at age 30 years.[315] NCCN currently recommends annual MRI screening between ages 25 and 29 years and annual MRI and mammography between ages 30 and 75 years.[85]

MRI

Because of the relative insensitivity of mammography in women with an inherited risk of breast cancer, a number of screening modalities have been proposed and investigated in high-risk women, including BRCA mutation carriers. Many studies have described the experience with breast MRI screening in women at risk of breast cancer, including descriptions of relatively large multi-institutional trials.[316-324]

Despite some limitations of these studies, they consistently demonstrate that breast MRI is more sensitive than either mammography or ultrasound for the detection of hereditary breast cancer. The results of six large studies are presented in Table 8, Summary of MRI Screening Studies in Women at Hereditary Risk of Breast Cancer.[316,318,319,322,325,326] Most cancers in these programs were screen detected, with only 6% of cancers presenting in the interval between screenings. The sensitivity of MRI (as defined by the study methodology) ranged from 71% to 100%. Of the combined studies, 77% of cancers were identified by MRI, and 42% were identified by mammography.

Concerns have been raised about the reduced specificity of MRI compared with other screening modalities. In one study, after the initial MRI screen, 16.5% of patients were recalled for further evaluation and an additional 7.6% of patients were recommended to undergo a short-interval follow-up examination at 6 months.[319] These rates declined significantly during later screening rounds, with fewer than 10% of the subjects recalled for more detailed MRI and fewer than 3% recommended to have short interval follow-up. In a second study, Magnetic Resonance Imaging for Breast Screening (MARIBS), the recall rate for additional evaluation was 10.7% per year.[318] The benign biopsy rates in the first study were 11% at first round, 6.6% at second round, and 4.7% at third round.[319] In the MARIBS study, the aggregate surgical biopsy rate was 9 per 1,000 screening episodes, though this may underestimate the burden because follow-up ultrasounds, core-needle biopsies, and fine-needle aspirations have not been included in the numerator of the MARIBS calculation.[318] The PPV of MRI has been calculated differently in the various series and fluctuates somewhat, depending on whether all abnormal examinations or only the examinations that result in a biopsy are counted in the denominator. Generally, the PPV of a recommendation for tissue sampling (as opposed to further investigation) is in the range of 50% in most series.

These trials appear to establish that MRI is superior to mammography in the detection of hereditary breast cancer, and that women participating in these trials including annual MRI screening were less likely to have a cancer missed by screening.[327] However, mammography may identify some cancers, particularly DCIS, that are not identified by MRI.[328]

Regarding downstaging, one screening study demonstrated that patients at risk of hereditary breast cancer were more likely to be diagnosed with small tumors and node-negative disease than were women in two nonrandomized control groups.[316] However, a randomized study of screening with or without MRI using tumor stage or mortality as an endpoint has not been performed. Despite the apparent sensitivity of MRI screening, some women in MRI-based programs will develop life-threatening breast cancer. In a prospective study of 51 BRCA1 and 41 BRCA2 mutation carriers screened with yearly mammograms and MRIs (of whom 80 had prophylactic oophorectomy), 11 breast cancers (9 invasive and 2 DCIS) were detected. Six cancers were first detected on MRI; three were first detected by mammogram; and two were interval cancers. All breast cancers occurred in BRCA1 mutation carriers, suggesting a continued high risk of BRCA1-related breast cancer after oophorectomy in the short term. These results suggest that surveillance and prevention strategies may have differing outcomes in BRCA1 and BRCA2 mutation carriers.[323]

A publication combining results from three large studies (MARIBS, a Canadian study, and a Dutch MRI screening study) demonstrated that when MRI was added to mammography, 80% of cancers detected in BRCA2 mutation carriers were either DCIS or invasive cancers smaller than 1 cm. In BRCA1 mutation carriers, 49% of cancers were DCIS or small invasive cancers. In addition, the authors predicted mortality benefits with the addition of MRI for both BRCA1 and BRCA2 mutation carriers. The model predicted breast cancer mortality reductions of 42% to 47% for mammography, 48% to 61% for MRI, and 50% to 62% for combined screening.[329] An additional study examining BRCA1/2 mutation carriers undergoing MRI between 1997 and 2006 has demonstrated that 97% of incident cancers were stage 0 or stage I.[330] The American Cancer Society and NCCN have recommended the use of annual MRI screening for women at hereditary risk of breast cancer.[85,331]

An additional question regarding the timing of mammography and MRI is whether they should be done simultaneously or in an alternating fashion (so that while each test is done annually, screening occurs every 6 months). One study has suggested that the most cost-effective screening strategy in BRCA1 and BRCA2 mutation carriers may be annual MRI beginning at age 25 years, with alternating MRI and digital mammography beginning at age 30 years.[315]

In summary, evidence strongly supports the integral role of breast MRI in breast cancer surveillance for BRCA1/2 mutation carriers.

Table 8. Summary of Magnetic Resonance Imaging (MRI) Screening Studies in Women at Hereditary Risk of Breast Cancer
Series Rijnsburger [324] Warner [319] MARIBS [318] Kuhl [322] Weinstein [325] Sardanelli [326] Totals 
N PatientsOverall2,1572366496876095014,839
BRCA1/BRCA2 Carriers59423612065443301,389
N Screening Episodes6,2534571,8811,6791,59211,862
N CancersBaseline22a1320100065
Subsequent97915171852208
Invasiveb78162981144186
In situ 199697858
Annual Incidence10.4/1,00019/1,000
Detected at Planned Screening782133271849226 (83%)
N Detected by Each ModalityMammography31c814972594 (42%)
MRI51c1727251242174 (77%)
Ultrasoundd71032646 (41%)
Follow-upMedian of 4.9 yMinimum of 1 y2–7 yMedian of 29.09 mo2 y3 y

aBased upon the first 1,909 women screened.[316]
bIncludes patients with invasive cancer only and patients with both invasive and in situ cancers.
cIncludes only 75 cancers detected in women who underwent both mammographic and MRI screening.
dRestricted to studies in which ultrasound was performed.

Level of evidence: 3

Ultrasound

Several studies have reported instances of breast cancer detected by ultrasound that were missed by mammography, as discussed in one review.[332] In a pilot study of ultrasound as an adjunct to mammography in 149 women with moderately increased risk based on family history, one cancer was detected, based on ultrasound findings. Nine other biopsies of benign lesions were performed. One was based on abnormalities on both mammography and ultrasound, and the remaining eight were based on abnormalities on ultrasound alone.[332] A large study of 2,809 women with dense breast tissue (ACRIN-6666) demonstrated that ultrasound increased the detection rate due to breast cancer screening from 7.6 per 1,000 with mammography alone to 11.8 per 1,000 for combined mammography and ultrasound.[333] However, ultrasound screening increases false-positive rates and appears to have a limited benefit in combination with MRI. In a multicenter study of 171 women (92% of whom were BRCA1/BRCA2 mutation carriers) undergoing simultaneous mammography, MRI, and ultrasound, no cancers were detected by ultrasound alone.[320] Uncertainties about ultrasound include the effect of screening on mortality, the rate and outcome of false-positive results, and access to experienced breast ultrasonographers.

Level of evidence: None assigned

Other screening modalities

A number of other techniques are under active investigation, including tomosynthesis, contrast-enhanced mammography, thermography, and radionuclide scanning. Additional evidence is needed before these techniques can be incorporated into clinical practice.

Risk-reducing surgeries

Risk-reducing mastectomy

In the general population, both subcutaneous mastectomy and simple (total) mastectomy have been used for prophylaxis. Between 90% and 95% of breast tissue is removed with subcutaneous mastectomy.[334] In a total or simple mastectomy, removal of the nipple-areolar complex increases the proportion of breast tissue removed compared with subcutaneous mastectomy. However, some breast tissue is usually left behind with both procedures. The risk of breast cancer after these procedures has not been well established.

The effectiveness of risk-reducing mastectomy (RRM) in women with BRCA1 or BRCA2 mutations has been evaluated in several studies. In one retrospective cohort study of 214 women considered to be at hereditary risk by virtue of a family history suggesting an autosomal dominant predisposition, three women were diagnosed with breast cancer after bilateral RRM, with a median follow-up of 14 years.[335] As 37.4 cancers were expected, the calculated risk reduction was 92% (95% CI, 76.6–98.3). In a follow-up subset analysis, 176 of the 214 high-risk women in this cohort study underwent mutation analysis of BRCA1 and BRCA2. Mutations were found in 26 women (18 deleterious, eight VUS). None of those women had developed breast cancer after a median follow-up of 13.4 years.[336] Two of the three women diagnosed with breast cancer after RRM were tested, and neither carried a mutation. The calculated risk reduction among mutation carriers was 89.5% to 100% (95% CI, 41.4%–100%), depending on the assumptions made about the expected numbers of cancers among mutation carriers and the status of the untested woman who developed cancer despite mastectomy. The result of this retrospective cohort study has been supported by a prospective analysis of 76 mutation carriers undergoing RRM and followed prospectively for a mean of 2.9 years. No breast cancers were observed in these women, whereas eight were identified in women undergoing regular surveillance (HR for breast cancer after RRM, 0 [95% CI, 0–0.36]).[337]

The Prevention and Observation of Surgical End Points study group estimated the degree of breast cancer risk reduction after RRM in BRCA1/BRCA2 mutation carriers. The rate of breast cancer in 105 mutation carriers who underwent bilateral RRM was compared with that in 378 mutation carriers who did not choose surgery. Bilateral mastectomy reduced the risk of breast cancer after a mean follow-up of 6.4 years by approximately 90%.[338]

Another study evaluated the effectiveness of contralateral RRM in affected women with hereditary breast cancer. In a group of 148 BRCA1 or BRCA2 mutation carriers, 79 of whom underwent RRM, the risk of contralateral cancer was reduced by 91% and was independent of the effect of risk-reducing oophorectomy. Survival was better among women undergoing RRM, but this result was apparently associated with higher mortality due to the index cancer or metachronous ovarian cancer in the group not undergoing surgery.[339] More recently, data from ten European centers on 550 women indicated that RRM was highly effective.[340] Similarly, a retrospective study of 593 BRCA1 and BRCA2 mutation carriers included 105 women with unilateral breast cancer who underwent contralateral risk-reducing mastectomy and had a 10-year survival rate of 89%, compared with 71% in the group who did not undergo contralateral risk-reducing surgery (P < .001).[341] However, these findings need to be confirmed in a larger series because of the potential presence of confounding factors (e.g., no information was provided regarding breast cancer screening practices, and there were missing grade and ER statuses for a large proportion of the sample).

A retrospective study of 390 women with early-stage breast cancer who were from families with a known BRCA1/2 mutation found a significant improvement in survival for women who underwent bilateral mastectomy compared with those who chose unilateral mastectomy.[342] A multivariate analysis controlling for age at diagnosis, year of diagnosis, and treatment and other prognostic factors found that contralateral mastectomy was associated with a 48% reduction in death from breast cancer. This was a relatively small study with a high potential for confounding of prognostic factors.

Studies describing histopathologic findings in RRM specimens from women with BRCA1 or BRCA2 mutations have been somewhat inconsistent. In two series, proliferative lesions associated with an increased risk of breast cancer (lobular carcinoma in situ, atypical lobular hyperplasia, atypical ductal hyperplasia, DCIS) were noted in 37% to 46% of women with mutations undergoing either unilateral or bilateral RRM.[267,343,344] In these series, 13% to 15% of patients were found to have previously unsuspected DCIS in the prophylactically removed breast. Among 47 cases of risk-reducing bilateral or contralateral mastectomies performed in known BRCA1 or BRCA2 mutation carriers from Australia, three (6%) cancers were detected at surgery.[345] In a study from Sweden among 100 women with a hereditary risk of breast cancer, unsuspected lesions were found in 13 out of 50 BRCA1/BRCA2 mutation carriers.[346] These findings were not replicated in a third retrospective cohort study. In this study, proliferative fibrocystic changes were noted in none of 11 bilateral mastectomies from patients with deleterious mutations and in only two of seven contralateral unilateral risk-reducing mastectomies in affected mutation carriers.[261]

Although data are sparse, the evidence indicates that while a substantial proportion of women with a strong family history of breast cancer are interested in discussing RRM as a treatment option, uptake varies according to culture, geography, health care system, insurance coverage, provider attitudes, and other social factors. For example, in one setting where the providers made one to two field trips to family gatherings for family information sessions and individual counseling, only 3% of unaffected carriers obtained RRM within 1 year of follow-up.[347] Among women at increased risk of breast cancer due to family history, fewer than 10% opted for mastectomy.[348] Selection of this option was related to breast cancer–related worry as opposed to objective risk parameters (e.g., number of relatives with breast cancer). In contrast, in a Dutch study of highly motivated women being followed every 6 months at a high-risk center, more than half (51%) of unaffected carriers opted for RRM. Almost 90% of the RRM surgeries were performed within 1 year of DNA testing. In this study, those most likely to have RRM were women younger than 55 years and with children.[349] In addition, self-perceived risk has been closely linked to interest in RRM.[348]

Assuming risk reduction in the range of 90%, a theoretical model suggests that for a group of 30-year-old women with BRCA1 or BRCA2 mutations, RRM would result in an average increased life expectancy of 2.9 to 5.3 years.[350] While these data are useful for public policy decisions, they cannot be individualized for clinical care as they include assumptions that cannot be fully tested. Another study of at-risk women showed a 70% time-tradeoff value, indicating that the women were willing to sacrifice 30% of life expectancy in order to avoid RRM.[351] A cost-effectiveness analysis study estimated that risk-reducing surgery (mastectomy and oophorectomy) is cost-effective compared with surveillance with regard to years of life saved, but not for improved quality of life.[352]

A computer-simulated survival analysis using a Monte Carlo model included breast MRI, mammography, RRM, and risk-reducing salpingo-oophorectomy (RRSO) and examined the impact of each of these separately on BRCA1 and BRCA2 mutation carriers.[353] The most effective strategy was found to be RRSO at age 40 years and RRM at age 25 years, in which case survival at age 70 years approached that of the general population. However, delaying mastectomy until age 40 years, or substituting RRM with screening with breast MRI and mammogram, had little impact on survival estimates. For example, replacing RRM with MRI-based screening in women with RRSO at age 40 years led to a 3% to 5% decrement in survival compared with RRM at age 25 years. The authors have developed an online tool.[354] As with any model, uncertainty remains due to numerous assumptions; however, this provides additional information for women and their providers who are making these difficult decisions.

The Society of Surgical Oncology has endorsed RRM as an option for women with BRCA1/BRCA2 mutations or strong family histories of breast cancer.[355]

Individual psychological factors have an important role in decision-making about RRM by unaffected women. Research is emerging about psychosocial outcomes of RRM. (Refer to the Psychosocial Outcome Studies section of this summary for more information.)

Level of evidence: 3aii

Risk-reducing salpingo-oophorectomy (RRSO)

In the general population, removal of both ovaries has been associated with a reduction in breast cancer risk of up to 75%, depending on parity, weight, and age at time of artificial menopause. (Refer to the PDQ summary on Breast Cancer Prevention for more information.) A Mayo Clinic study of 680 women at various levels of familial risk found that in women younger than 60 years who had bilateral oophorectomy, the likelihood of breast cancers developing was reduced for all risk groups.[356] Ovarian ablation, however, is associated with important side effects such as hot flashes, impaired sleep habits, vaginal dryness, dyspareunia, and increased risk of osteoporosis and heart disease. A variety of strategies may be necessary to counteract the adverse effects of ovarian ablation.

In support of early small studies,[357,358] a retrospective study of 551 women with disease-associated BRCA1 or BRCA2 mutations found a significant reduction in risk of breast cancer (HR, 0.47; 95% CI, 0.29–0.77) and ovarian cancer (HR, 0.04; 95% CI, 0.01–0.16) after RRSO.[359] A prospective, single-institution study of 170 women with BRCA1 or BRCA2 mutations showed a similar trend. With RRSO, the HR was 0.15 (95% CI, 0.02–1.31) for ovarian, fallopian tube, or primary peritoneal cancer, and 0.32 (95% CI, 0.08–1.2) for breast cancer; the HR for either cancer was 0.25 (95% CI, 0.08–0.74).[360] A prospective, multicenter study of 1,079 women followed for a median of 30 to 35 months found that while RRSO was associated with reductions in breast cancer risk in both BRCA1 and BRCA2 mutation carriers, the risk reduction was more pronounced in BRCA2 carriers (HR, 0.28; 95% CI, 0.08–0.92).[361] A meta-analysis of all reports of RRSO and breast and ovarian/fallopian tube cancer in BRCA1/BRCA2 mutation carriers confirmed that RRSO was associated with a significant reduction in breast cancer risk (overall: HR, 0.49; 95% CI, 0.37–0.65; BRCA1: HR, 0.47; 95% CI, 0.35–0.64; BRCA2: HR, 0.47; 95% CI, 0.26–0.84).[362]

In addition to the reduction in incidence of both breast and ovarian cancer, a prospective, multicenter, cohort study of 2,482 BRCA1/BRCA2 mutation carriers has reported an association of RRSO with a reduction in all-cause mortality (HR, 0.40; 95% CI, 0.26–0.61), breast cancer–specific mortality (HR, 0.44; 95% CI, 0.26–0.76), and ovarian cancer–specific mortality (HR, 0.21; 95% CI, 0.06–0.80).[363]

Level of evidence: 3ai

Chemoprevention

Tamoxifen

Tamoxifen (a synthetic antiestrogen) increases breast-cell growth inhibitory factors and concomitantly reduces breast-cell growth stimulatory factors. The National Surgical Adjuvant Breast and Bowel Project Breast Cancer Prevention Trial (NSABP-P-1), a prospective, randomized, double-blind trial, compared tamoxifen (20 mg/day) with placebo for 5 years. Tamoxifen was shown to reduce the risk of invasive breast cancer by 49%. The protective effect was largely confined to ER-positive breast cancer, which was reduced by 69%. The incidence of ER-negative cancer was not significantly reduced.[364] Similar reductions were noted in the risk of preinvasive breast cancer. Reductions in breast cancer risk were noted both among women with a family history of breast cancer and in those without a family history. An increased incidence of endometrial cancers and thrombotic events occurred among women older than 50 years. Interim data from two European tamoxifen prevention trials did not show a reduction in breast cancer risk with tamoxifen after a median follow-up of 48 months [365] or 70 months,[366] respectively. In one trial, however, reduction in breast cancer risk was seen among a subgroup who also used hormone replacement therapy (HRT).[365] These trials varied considerably in study design and populations. (Refer to the PDQ summary on Breast Cancer Prevention for more information.)

A substudy of the NSABP-P-1 trial evaluated the effectiveness of tamoxifen in preventing breast cancer in BRCA1/BRCA2 mutation carriers older than 35 years. BRCA2-positive women benefited from tamoxifen to the same extent as BRCA1/BRCA2 mutation–negative participants; however, tamoxifen use among healthy women with BRCA1 mutations did not appear to reduce breast cancer incidence. These data must be viewed with caution in view of the small number of mutation carriers in the sample (8 BRCA1 carriers and 11 BRCA2 carriers).[367]

Level of evidence: 1

In contrast to the very limited data on primary prevention in BRCA1 and BRCA2 mutation carriers with tamoxifen, several studies have found a protective effect of tamoxifen on the risk of contralateral breast cancer.[368-370] In one study involving approximately 600 BRCA1/BRCA2 mutation carriers, tamoxifen use was associated with a 51% reduction in contralateral breast cancer.[368] An update to this report examined 285 BRCA1/BRCA2 mutation carriers with bilateral breast cancer and 751 BRCA1/BRCA2 mutation carriers with unilateral breast cancer (40% of these patients were included in their initial study). Tamoxifen was associated with a 50% reduction in contralateral breast cancer risk in BRCA1 mutation carriers and a 58% reduction in BRCA2 mutation carriers. Tamoxifen did not appear to confer benefit in women who had undergone an oophorectomy, although the numbers in this subgroup were quite small.[370] Another study that involved 160 BRCA1/BRCA2 mutation carriers demonstrated that tamoxifen use after the treatment of breast cancer with lumpectomy and radiation was associated with a 69% reduction in the risk of contralateral breast cancer.[369] In another study, 2,464 BRCA1/2 mutation carriers with a personal history of breast cancer were identified from three family cohorts. Using both retrospective and prospective data, researchers found a significant decrease in the risk of contralateral breast cancer among women who received adjuvant tamoxifen therapy after their diagnosis. This association persisted after researchers adjusted for age at diagnosis and the ER status of the first cancer. A major limitation of this study is the lack of information on ER status of the first breast cancer in 56% of the women.[371] These studies are limited by their retrospective, case-control designs and the absence of information regarding estrogen receptor status in the primary tumor.

The STAR trial (NSABP-P-2) included more than 19,000 women and compared 5 years of raloxifene versus tamoxifen in reducing the risk of invasive breast cancer.[372] There was no difference in incidence of invasive breast cancer at a mean follow-up of 3.9 years; however, there were fewer noninvasive cancers in the tamoxifen group. The incidence of thromboembolic events and hysterectomy was significantly lower in the raloxifene group. Detailed quality of life data demonstrate slight differences between the two arms.[373] Data regarding efficacy in BRCA1 or BRCA2 mutation carriers are not available.

The effect of tamoxifen on ovarian cancer risk was studied in 714 BRCA1 mutation carriers. All subjects had a prior history of breast cancer; use of tamoxifen was not associated with an increased risk of subsequent ovarian cancer (odds ratio [OR], 0.78; 95% CI, 0.46–1.33).[374]

Level of evidence: 1

Reproductive factors

Pregnancy and lactation

In the general population, breast cancer risk increases with early menarche and late menopause, and is reduced at early first full-term pregnancy. (Refer to the PDQ summary on Breast Cancer Prevention for more information.) In the Nurses’ Health Study, these were risk factors among women who did not have a mother or sister with breast cancer.[375] Among women with a family history of breast cancer, pregnancy at any age appeared to be associated with an increase in risk of breast cancer, persisting to age 70 years.

One study evaluated risk modifiers among 333 female carriers of a BRCA1 high-risk mutation. In women with known mutations of the BRCA1 gene, early age at first live birth and parity of three or more have been associated with a lowered risk of breast cancer. A RR of 0.85 was estimated for each additional birth, up to five or more; however, increasing parity appeared to be associated with an increased risk of ovarian cancer.[376,377] In a case-control study from New Zealand, investigators noted no difference in the impact of parity upon the risk of breast cancer between women with a family history of breast cancer and those without a family history.[378]

Studies of the effect of pregnancy on breast cancer risk have revealed complex results and the relationship with parity has been inconsistent and may vary between BRCA1 and BRCA2 mutation carriers.[126,379,380] Parity has more consistently been associated with a reduced risk of breast cancer in BRCA1 mutation carriers.[125,126,379-381] Of note, neither therapeutic nor spontaneous abortions appear to be associated with an increased breast cancer risk.[126,382]

Level of evidence: 4aii

In the general population, breastfeeding has been associated with a slight reduction in breast cancer risk in a few studies, including a large collaborative reanalysis of multiple epidemiologic studies,[383] and at least one study suggests that it may be protective in BRCA1 mutation carriers. In a multicenter, breast cancer case-control study of 685 BRCA1 and 280 BRCA2 mutation carriers with breast cancer and 965 mutation carriers without breast cancer drawn from multiple-case families, among BRCA1 mutation carriers, breastfeeding for one year or more was associated with approximately a 45% reduced risk of breast cancer.[127] No such reduced risk was observed among BRCA2 mutation carriers. A second study failed to confirm this association.[382]

Oral contraceptives

There is no consistent evidence that the use of oral contraceptives (OCs) increases the risk of breast cancer in the general population.[384] (Refer to the PDQ summary on Breast Cancer Prevention for more information.)

Although several smaller studies have reported a slightly increased risk of breast cancer with OC use in BRCA1/BRCA2 mutation carriers,[385,386] a meta-analysis concluded that the associated risk is not significant with more recent OC formulations.[123] However, OCs formulated before 1975 were associated with an increased risk of breast cancer.[123] A large proportion of patients upon which this meta-analysis was based were drawn from three large studies summarized in Table 9.[387-389]

Table 9. Oral Contraceptive (OC) Use and Breast Cancer Risk in BRCA1/BRCA2 Mutation Carriers
 Brohet 2007a [387] Haile 2006b,c [388] Narod 2002b [389]  
Study Population BRCA1 Carriers with Breast Cancer N = 597N = 195; diagnosis < age 50 yN = 981
BRCA2 Carriers with Breast Cancer N = 249N = 128; diagnosis < age 50 yN = 330
Ever Use OC BRCA1 1.47 [CI 1.13–1.91]0.64 [CI 0.35–1.16]1.38 [CI 1.11–1.72] P = .003a
BRCA2 1.49 [Cl 0.8–2.7]1.29 [Cl 0.61–2.76]0.94 [Cl 0.72–1.24]
Age Use <20 y BRCA1 1.41 [Cl 0.99–2.01]0.84 [Cl 0.45–1.55]1.36 [Cl 1.11–1.67] P = .003
BRCA2 1.25 [Cl 0.57–2.74]1.64 [Cl 0.77–3.46]Not reported
Total Duration BRCA1 <9 y: 1.51 [Cl 1.1–2.08]<5 y: 0.61 [Cl 0.31–1.17]<10 y: 1.36 [Cl 1.11–167] P = .003
BRCA2 <9 y: 2.27 [Cl 1.1–4.65]<5 y: 0.79 [Cl 0.26–2.37]<10 y: 0.82 [Cl 0.56–1.91]
Use Before Full-term Pregnancy BRCA1 >4 y: 1.49 [Cl 1.05–2.11]>4 y: 0.69 [Cl 0.41–1.16]Not evaluated
BRCA2 >4 y: 2.58 [Cl 1.21–5.49]>4 y: 2.08 [Cl 1.02–4.25] trend per y: 1.11; P trend = .01
Use Before 1975 BRCA1 1.48 [Cl 1.11–1.98]Excluded patients who used OC before 19751.42 [Cl 1.17–1.75] P < .001
BRCA2 1.36 [Cl 0.71–2.58]
Use After 1975 BRCA1 1.57 [Cl 1.11–2.22]0.65 [Cl 0.36–1.19]Not evaluated
BRCA2 1.53 [Cl 0.75–3.12]1.21 [Cl 0.56–2.58]

CI = confidence interval.
aReports risk estimates in the form of hazard ratios with 95% confidence intervals.
bReports risk estimates in the form of odds ratios with 95% confidence intervals.
cRisk estimates restricted to BRCA mutation carriers younger than 40 years.

When counseling patients about contraceptive options and preventive actions, the potential impact of OC use upon the risk of breast cancer and ovarian cancer and other health-related effects of OCs need to be considered. A number of important issues remain unresolved, including the potential differences between BRCA1 and BRCA2 mutation carriers, effect of age and duration of exposure, and effect of OCs on families with highly penetrant early-onset breast cancer.

Level of evidence: 3aii

(Refer to the Oral contraceptives section in the Chemoprevention section of this summary for a discussion of OC use and ovarian cancer in this population.)

Hormone replacement therapy

Both observational and randomized clinical trial data suggest an increased risk of breast cancer associated with HRT in the general population.[390-393] The Women’s Health Initiative (WHI) was a randomized controlled trial of approximately 160,000 postmenopausal women that investigated the risks and benefits of dietary interventions and hormone therapy to reduce the incidence of heart disease, breast cancer, colorectal cancer, and fractures. The estrogen-plus-progestin arm of the study, in which more than 16,000 women were randomly assigned to receive combined hormone therapy or placebo, was halted early because health risks exceeded benefits.[392,393] One of the adverse outcomes prompting closure was a significant increase in both total (245 vs. 185 cases) and invasive (199 vs. 150) breast cancers (RR, 1.24; 95% CI, 1.02–1.50; P < .001) in women randomly assigned to receive estrogen and progestin.[393] Results of a follow-up study suggest that the recent reduction in breast cancer incidence, especially among women aged 50 to 69 years, is predominantly related to decrease in use of combined estrogen plus progestin HRT.[394] HRT-related breast cancers had adverse prognostic characteristics (more advanced stages and larger tumors) compared with cancers occurring in the placebo group, and HRT was also associated with a substantial increase in abnormal mammograms.[393]

Breast cancer risk associated with postmenopausal HRT has been variably reported to be increased [395-397] or unaffected by a family history of breast cancer;[376,398,399] risk did not vary by family history in the meta-analysis.[384] The WHI study has not reported analyses stratified on breast cancer family history, and subjects have not been systematically tested for BRCA1/BRCA2 mutations.[393] Short-term use of hormones for treatment of menopausal symptoms appears to confer little or no breast cancer risk in the general population.[400]

Hormone replacement therapy in BRCA1/BRCA2 mutation carriers

The effect of HRT on breast cancer risk among carriers of a BRCA1 or BRCA2 mutation has been examined in two studies. In a prospective study of 462 BRCA1 or BRCA2 mutation carriers, bilateral RRSO (n = 155) was significantly associated with breast cancer risk-reduction overall (HR, 0.40; 95% CI, 0.18–0.92). Using mutation carriers without bilateral RRSO or HRT as the comparison group, HRT use (n = 93) did not significantly alter the reduction in breast cancer risk associated with bilateral RRSO (HR, 0.37; 95% CI, 0.14–0.96).[401] In a matched case-control study of 472 postmenopausal women with BRCA1 mutations, HRT use was associated with an overall reduction in breast cancer risk (OR, 0.58; 95% CI, 0.35–0.96; P = .03). A nonsignificant reduction in risk was observed both in women who had undergone bilateral oophorectomy and in those who had not. Women taking estrogen alone had an OR of 0.51 (95% CI, 0.27–0.98; P = .04), while the association with estrogen and progesterone was not statistically significant (OR, 0.66; 95% CI, 0.34–1.27; P = .21).[402] Especially given the differences in estimated risk associated with HRT between observational studies and the WHI, these findings should be confirmed in randomized prospective studies,[403] but they suggest that HRT in BRCA1/BRCA2 mutation carriers neither increases breast cancer risk nor negates the protective effect of oophorectomy.

Level of evidence: 3aii

Ovarian cancer

Screening/surveillance

Refer to the PDQ summary on Ovarian Cancer Screening for information on screening in the general population and to the PDQ summary Levels of Evidence for Cancer Genetics Studies for information about levels of evidence related to screening and prevention. The latter also outlines the five requirements that must be met before it is considered appropriate to screen for a particular medical condition as part of routine medical practice.

Clinical examination

In the general population, clinical examination of the ovaries has neither the specificity nor the sensitivity to reliably identify early ovarian cancer. No data exist regarding the benefit of clinical examination of the ovaries (bimanual pelvic examination) in women at inherited risk of ovarian cancer.

Level of evidence: None assigned

Transvaginal ultrasound

In the general population, transvaginal ultrasound (TVUS) appears to be superior to transabdominal ultrasound in the preoperative diagnosis of adnexal masses. Both techniques have lower specificity in premenopausal women than in postmenopausal women due to the cyclic menstrual changes in premenopausal ovaries (e.g., transient corpus luteum cysts) that can cause difficulty in interpretation. The randomized prospective Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO-1) found no reduction in mortality with the annual use of combined TVUS and cancer antigen (CA) 125 in screening asymptomatic postmenopausal women at general-population risk of ovarian cancer.[404]

Data are limited regarding the potential benefit of TVUS in screening women at inherited risk of ovarian cancer. A number of retrospective studies have reported experience with ovarian cancer screening in high-risk women using TVUS with or without CA-125.[182,293,405-414] However, there is little uniformity in the definition of high-risk criteria and compliance with screening, and in whether cancers detected were incident or prevalent. One of the largest reported studies included 888 BRCA1/BRCA2 mutation carriers who were screened annually with TVUS and CA-125. Ten women developed ovarian cancer; five of the ten developed interval cancers after normal screening results within 3 to 10 months before diagnosis. Five of the ten ovarian cancers were screen-detected incident cases, which had normal screening results within 6 to 14 months before diagnosis. Of these five cases, four were stage IIIB or IV.[405]

A similar study reported the results of annual TVUS and CA-125 in a cohort of 312 high-risk women (152 BRCA1/BRCA2 mutation carriers).[407] Of the four cancers that were detected due to abnormal TVUS and CA-125, all four patients were symptomatic, and three had advanced-stage disease. Annual screening of BRCA1/BRCA2 mutation carriers with pelvic ultrasound, TVUS, and CA-125 failed to detect early-stage ovarian cancer among 241 BRCA1/BRCA2 mutation carriers in a study from the Netherlands.[415] Three cancers were detected over the course of the study, all advanced stage IIIC disease.[415] Finally, a study of 1,100 moderate- and high-risk women who underwent annual TVUS and CA-125 reported that ten of 13 ovarian tumors were detected due to screening. Only five of ten were stage I or II.[406] There are limited data related to the efficacy of semiannual screening with TVUS and CA-125.[293,413]

The first prospective study of TVUS and CA-125 with survival as the primary outcome was completed in 2009. Of the 3,532 high-risk women screened, 981 were BRCA mutation carriers, of which 49 developed ovarian cancer. The 5- and 10-year survival was 58.6% (95% CI, 50.9–66.3) and 36% (95% CI, 27–45), respectively, and there was no difference in survival between carriers and noncarriers. A major limitation of the study was the absence of a control group. Despite limitations, this study suggests that annual surveillance by TVUS and CA-125 level appear to be ineffective in detecting tumors at an early stage to substantially influence survival.[416]

Level of evidence: 4

Serum CA-125

Serum CA-125 screening for ovarian cancer in high-risk women has been evaluated in combination with TVUS in a number of retrospective studies, as described in the previous section.[182,293,405-413]

The National Institutes of Health (NIH) Consensus Statement on Ovarian Cancer recommended against routine screening of the general population for ovarian cancer with serum CA-125. (Refer to the Combined CA-125 and TVU section in the PDQ summary on Ovarian Cancer Screening for more information.) The NIH Consensus Statement did, however, recommend that women at inherited risk of ovarian cancer undergo TVUS and serum CA-125 screening every 6 to 12 months, beginning at age 35 years.[417] The Cancer Genetics Studies Consortium task force has recommended that female carriers of a deleterious BRCA1 mutation undergo annual or semiannual screening using TVUS and serum CA-125 levels, beginning at age 25 to 35 years.[295] Both recommendations are based solely on expert opinion and best clinical judgment.

Level of evidence: 5

Other candidate ovarian cancer biomarkers

The need for effective ovarian cancer screening is particularly important for women carrying mutations in BRCA1 and BRCA2, and the mismatch repair (MMR) genes (e.g., MLH1, MSH2, MSH6, PMS2), disorders in which the risk of ovarian cancer is high. There is a special sense of urgency for BRCA1 mutation carriers, in whom cumulative lifetime risks of ovarian cancer may exceed 40%.

Thus, it is expected that many new ovarian cancer biomarkers (either singly or in combination) will be proposed as ovarian cancer screening strategies during the next 5 to 10 years. While this is an active area of research with a number of promising new biomarkers in early development, at present, none of these biomarkers alone or in combination have been sufficiently well studied to justify their routine clinical use for screening purposes, either in the general population or in women at increased genetic risk.

Before addressing information related to emerging ovarian cancer biomarkers, it is important to consider the several steps that are required to develop and, more importantly, validate a new biomarker. One useful framework is that published by the National Cancer Institute Early Detection Research Network investigators.[418] They indicated that the goal of a cancer-screening program is to detect tumors at an early stage so that treatment is likely to be successful. The gold standard by which such programs are judged is whether the death rate from the cancer for which screening is performed is reduced among those being screened. In addition, the screening test must be sufficiently noninvasive and inexpensive to allow widespread use in the population to be screened. Maintaining high test specificity (i.e., few false-positive results) is essential for a population screening test, because even a low false-positive rate results in many people having to undergo unnecessary and costly diagnostic procedures and psychological stress. It is likely that the use of several such cancer biomarkers in combination will be required for a screening test to be both sensitive and specific.

Furthermore, a clinically useful test must have a high PPV (a parameter derived from sensitivity, specificity, and disease prevalence in the screened population). Practically speaking, a biomarker with a PPV of 10% implies that ten surgical procedures would be required to identify one case of ovarian cancer; the remaining nine surgeries would represent false-positive test findings. In general, the ovarian cancer research community considers biomarkers with a PPV less than 10% to be clinically unacceptable, given the morbidity related to bilateral salpingo-oophorectomy. Finally, it is important to keep in mind that while novel biomarkers may be present in the sera of women with advanced ovarian cancer (which comprise the vast majority of cases analyzed in the early phases of biomarker development), they may or may not be detectable in women with early stage disease, which is essential if the screening test is to be clinically useful.

It has been suggested that there are five general phases in biomarker development and validation:

Phase I — Preclinical exploratory studies

  • Identify potentially discriminating biomarkers.
  • Usually done by comparing gene over- or under-expression in the tumor compared with normal tissue.
  • Because many exploratory analyses in large numbers of genes are performed at this stage, one or more may seem to have good discriminating ability between cancers and normal tissue by random chance alone.

Phase 2 — Clinical assay development for clinical disease

  • Develop a clinical assay that can be obtained on noninvasively obtained samples (e.g., a blood specimen).
  • Often the test targets the protein product of one of the genes found to be of interest in phase I.
  • The goal is to describe the performance characteristics of the assay for distinguishing between subjects with and without cancer. At this point, the assay should be in its final configuration and remain stable throughout the following phases.
  • IMPORTANT: Because the case subjects in a phase 2 study already have cancer, with assay results obtained at the time of disease diagnosis, one cannot determine whether disease can be detected early with a given biomarker.

Phase 3 — Retrospective longitudinal repository studies

  • Compare clinical specimens collected from cancer case subjects before their clinical diagnosis with specimens from subjects who have not developed cancer.
  • Evaluate, as a function of time before clinical diagnosis, the biomarker’s ability to detect preclinical disease.
  • Define the criteria for a positive screening test in preparation for phase 4.
  • Explore the influence of other patient characteristics (e.g., age, gender, smoking status, medication use) on the ability of the biomarker to discriminate between those with and without preclinical disease.

Phase 4 — Prospective screening studies

  • Determine the operating characteristics of the biomarker-based screening test in a population for which the test is intended.
  • Measure the detection rate (number of abnormal tests among all those with the disease) and the false-positive rate (the number of abnormal tests among all those who do not have the disease).
  • Evaluate whether the cancers detected by the test are being found at an early stage, a point at which treatment is more likely to be curative.
  • Assess whether the test is acceptable in a population of persons for whom it is intended. Will subjects comply with the test schedule and results?

Phase 5 — Cancer control studies

  • Ideally, conduct randomized controlled clinical trials in clinically relevant populations, in which one arm is subjected to screening and appropriate intervention if screen-positive, while the other arm is not screened.
  • Determine whether the death rate of the cancer being screened for is reduced among those who use the screening test.
  • Obtain information about the costs of screening and treatment of screen-detected cancers.

Finally, for a validated biomarker test to be considered appropriate for use in a particular population, it must have been evaluated in that specific population without prior selection of known positives and negatives. In addition, the test must demonstrate clinical utility, that is, a positive net balance of benefits and risks associated with the application of the test. These may include improved health outcomes and net psychosocial and economic benefits.[419]

Ovarian cancer poses a unique challenge relative to the potential impact of false-positive test results. There are no reliable noninvasive diagnostic tests for early stage disease, and clinically-significant early stage cancer may not be grossly visible at the time of exploratory surgery.[283] Consequently, it is likely that some patients will be reassured that their abnormal test does not indicate the presence of cancer only by having their ovaries and fallopian tubes surgically removed and examined microscopically. High test specificity (i.e., a very low false-positive rate) is required to avoid unnecessary surgery and induction of premature menopause in false positive women.

Variations on CA-125

CA-125 plus an ovarian cancer symptom index

An ovarian cancer symptom index for predicting the presence of cancer was evaluated in 75 cases and 254 high-risk controls (BRCA mutation carriers or women with a strong family history of breast and ovarian cancer).[420] Women had a positive symptom index if they reported any of the predefined symptoms (bloating or increase in abdominal size, abdominal or pelvic pain, and difficulty eating or feeling full quickly) more than 12 times per month occurring only within the prior 12 months. CA-125 values greater than 30 U/mL were considered abnormal. The symptom index independently predicted the presence of ovarian cancer, after controlling for CA-125 levels (P < .05). The combination of an elevated CA-125 and a positive-symptom index correctly identified 89.3% of the cases. The symptom index correlated with the presence of cancer in 50% of the affected women who did not have elevated CA-125 levels, but 11.8% of the high-risk controls without cancer also had a positive-symptom index. The authors suggested that a composite index including both CA-125 and the symptom index had better performance characteristics than either test used alone, and that this strategy might be used as a first screen in a multistep screening program. Additional test performance validation and determination of clinical utility are required in unselected screening populations.

Level of evidence: 5

Risk of ovarian cancer algorithm

A novel modification of CA-125 screening is based on the hypothesis that rising CA-125 levels over time may provide better ovarian cancer screening performance characteristics than simply classifying CA-125 as normal or abnormal based on an arbitrary cut-off value. This has been implemented in the form of the risk of ovarian cancer algorithm (ROCA), an investigational statistical model that incorporates serial CA-125 test results and other covariates into a computation that produces an estimate of the likelihood that ovarian cancer is present in the screened subject. The first report of this strategy, based on reanalysis of 5,550 average-risk women from the Stockholm Ovarian Cancer screening trial, suggested that ovarian cancer cases and controls could be distinguished with 99.7% sensitivity, 83% specificity, and a PPV of 16%. That PPV represents an eightfold increase over the 2% PPV reported with a single measure of CA-125.[421] This report was followed by applying the ROCA to 33,621 serial CA-125 values obtained from the 9,233 average-risk postmenopausal women in a prospective British ovarian cancer screening trial.[422] The area under the receiver operator curve increased from 84% to 93% (P = .01) for ROCA compared with a fixed CA-125 cutoff. These observations represented the first evidence that preclinical detection of ovarian cancer might be improved using this screening strategy. A prospective study of 13,000 normal volunteers aged 50 years and older in England used serial CA-125 values and the ROCA to stratify participants into low, intermediate, and elevated risk subgroups.[423] Each had its own prescribed management strategy, including TVUS and repeat CA-125 either annually (low risk) or at 3 months (intermediate risk). Using this protocol, ROCA was found to have a specificity of 99.8% and a PPV of 19%.

Two prospective trials in England utilized the ROCA. The United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) randomly assigned normal-risk women to either (1) no screening, (2) annual ultrasound, or (3) multimodal screening (N = 202,638; accrual completed; follow-up ends in 2014), and the U.K. Familial Ovarian Cancer Screening Study (UKFOCSS) targeted high-risk women (accrual completed). There are also two high-risk cohorts using the ROCA under evaluation in the United States: the Cancer Genetics Network ROCA Study (N = 2,500; follow-up complete; analysis underway) and the Gynecologic Oncology Group Protocol 199 (GOG-0199; enrollment complete; follow-up ended in 2011).[424] Thus, additional data regarding the utility of this currently investigational screening strategy will become available within the next few years.

Level of evidence: 4

Miscellaneous new markers

A wide array of new candidate ovarian cancer biomarkers has been described during the past decade, e.g., HE4; mesothelin; kallikreins 6, 10, and 11; osteopontin; prostasin; M-CSF; OVX1; lysophosphatidic acid; vascular endothelial growth factor B7-H4; and interleukins 6 and 8.[425-427] These have been singly studied, in combination with CA-125, or in various other permutations. Most of the study populations are relatively small and comprise highly-selected known ovarian cancer cases and healthy controls of the type evaluated in early biomarker development phases 1 and 2. Results have not been consistently replicated in multiple studies; presently, none are considered ready for widespread clinical application.

Level of evidence: 5

Proteomics

Initially, mass spectroscopy of serum proteins was combined with complex analytic algorithms to identify protein patterns that might distinguish between ovarian cancer cases and controls.[428] This approach assumed that pattern recognition alone would be sufficient to permit such discrimination, and that identification of the specific proteins responsible for the patterns identified was not required. Subsequently, this strategy has been modified, using similar laboratory tools, to identify finite numbers of specific known serum markers that may be used in place of, or in conjunction with, CA-125 measurements for the early detection of cancer.[429] These studies [427,430] have generally been small case-control studies that are limited by sample size and the number of early-stage cancer cases included. Further evaluation is needed to determine whether any additional markers identified in this fashion have clinical utility for the early detection of ovarian cancer in the unselected clinical population of interest.

Level of evidence: 5

Multiplex assays

Because individual biomarkers have not met the criteria for an effective screening test, it has been suggested that it may be necessary to combine multiple ovarian cancer biomarkers to obtain satisfactory screening test results. This strategy was employed to quantitatively analyze six serum biomarkers (leptin, prolactin, osteopontin, insulin-like growth factor II, macrophage inhibitory factor, and CA-125), using a multiplex, bead-based platform.[431] A similar assay was available commercially under the trade name OvaSure until its voluntary withdrawal from the market by the manufacturer.[Response to FDA Warning Letter]

The cases in this study were newly-diagnosed ovarian cancer patients who had blood collected just before surgery: 36 were stage I and II; 120 were stage III and IV. The controls were healthy age-matched individuals who had not developed ovarian cancer within 6 months of blood draw. Neither cases nor controls in this study were well characterized regarding their familial and or genetic risk status, but they have been suggested to comprise a high-risk population. First, 181 controls and 113 ovarian cancer cases were tested to determine the initial panel of biomarkers that best discriminated between cases and controls (training set). The resulting panel was applied to an additional 181 controls and 43 ovarian cancer cases (test set). Pooling both early- and late-stage ovarian cancer across the combined training and test sets, performance characteristics were reported as a sensitivity of 95.3% and a specificity of 99.4%, with a PPV of 99.3% and a negative predictive value of 99.2%, using a formula that assumed an ovarian cancer prevalence of about 50%, as seen in the highly selected research population.

To avoid biases that may make test performance appear to be better than it really is, combining training populations and test populations in analyses of this sort is generally not recommended.[432] The most appropriate prevalence to use is the disease prevalence in the unselected population to be screened. The prevalence of ovarian cancer in the general population is 1 in 2,500. In a recently published correction to their manuscript,[431] the authors assumed that the prevalence of ovarian cancer in the screened population was 1/2,500 (0.04%) and recalculated the PPV to be only 6.5%. On that basis the investigators have retracted their claim that this test is suitable for population screening. If this test were used in patients at increased risk of ovarian cancer, the actual prevalence in such a target population is likely to be higher than that observed in the general population, but well below the assumed 50% figure used in the published analysis. This revised PPV of 6.5% indicates that approximately 1 in 15 women with a positive test would in fact have ovarian cancer, and only a fraction of those with ovarian cancer would be stages I or II. The remaining 14 positive tests would represent false-positives, and these women would be at risk of exposure to needless anxiety and potentially morbid diagnostic procedures, including bilateral salpingo-oophorectomy.

Viewed in the context of the criteria previously described,[418] this assay would be classified as phase 2 in its development. While this appears to be a promising avenue of ovarian cancer screening research, additional validation is required, particularly in an unselected population representative of the clinical screening population of interest. A recent position statement by the Society of Gynecologic Oncologists regarding this assay indicated “it is our opinion that additional research is needed to validate the test’s effectiveness before offering it to women outside of the context of a research study conducted with appropriate informed consent under the auspices of an Institutional Review Board.”

Level of evidence: 5

Risk-reducing surgery

RRSO

Numerous studies have found that women with an inherited risk of breast and ovarian cancer have a decreased risk of ovarian cancer after RRSO. A retrospective study of 551 women with disease-associated BRCA1 or BRCA2 mutations found a significant reduction in risk of breast cancer (HR, 0.47; 95% CI, 0.29–0.77) and ovarian cancer (HR, 0.04; 95% CI, 0.01–0.16) after bilateral oophorectomy.[359] A prospective, single-institution study of 170 women with BRCA1 or BRCA2 mutations showed a similar trend.[360] With oophorectomy, the HR was 0.15 (95% CI, 0.02–1.31) for ovarian, fallopian tube, or primary peritoneal cancer, and 0.32 (95% CI, 0.08–1.2) for breast cancer; the HR for either cancer was 0.25 (95% CI, 0.08–0.74). A prospective multicenter study of 1,079 women who were followed up for a median of 30 to 35 months found that RRSO is highly effective in reducing ovarian cancer risk in BRCA1 and BRCA2 mutation carriers. This study also showed that RRSO was associated with reductions in breast cancer risk in both BRCA1 and BRCA2 mutation carriers; however, the breast cancer risk reduction was more pronounced in BRCA2 carriers (HR, 0.28; 95% CI, 0.08–0.92).[361] In a case-control study in Israel, bilateral oophorectomy was associated with reduced ovarian/peritoneal cancer risks (OR, 0.12; 95% CI, 0.06–0.24).[433] A meta-analysis of all reports of RRSO and breast and ovarian/fallopian tube cancer in BRCA1/BRCA2 mutation carriers confirmed that RRSO was associated with a significant reduction in risk of ovarian or fallopian tube cancer (HR, 0.21; 95% CI, 0.12–0.39). The study also found a significant reduction in risk of breast cancer (overall: HR, 0.49; 95% CI, 0.37–0.65; BRCA1: HR, 0.47; 95% CI, 0.35–0.64; BRCA2: HR, 0.47; 95% CI, 0.26–0.84).[362] Subsequently, a matched case-control study of 2,854 pairs of women with a BRCA1 or BRCA2 mutation with or without breast cancer showed a greater breast cancer risk reduction with surgical menopause (OR, 0.52; 95% CI, 0.40–0.66) than with natural menopause (OR, 0.81; 95% CI, 0.62–1.07). This study also reported a highly significant reduction in breast cancer risk among women who had an oophorectomy after natural menopause (OR, 0.13; 95% CI, 0.02–0.54; P = .006).[434] Another study of 5,783 women with BRCA1 or BRCA2 mutations who were followed up for an average of 5.6 years reported that 68 of 186 women who developed either ovarian, fallopian, or peritoneal cancer had died. The HR for these cancers with bilateral oophorectomy was 0.20 (95% CI, 0.13–0.30; P = .001). In BRCA mutation carriers without a history of cancer, the HR for all-cause mortality to age 70 years associated with oophorectomy was 0.23 (95% CI, 0.13–0.39; P < .001).[435]

In addition to a reduction in risk of ovarian and breast cancer, RRSO may also significantly improve overall survival (OS) and breast and ovarian cancer-specific survival. A prospective cohort study of 666 women with germline mutations in BRCA1 and BRCA2 found an HR for overall mortality of 0.24 (95% CI, 0.08–0.71) in women who had RRSO compared with women who did not.[436] This study provides the first evidence to suggest a survival advantage among women undergoing RRSO.

Studies on the degree of risk reduction afforded by RRSO have begun to clarify the spectrum of occult cancers discovered at the time of surgery. Primary fallopian tube cancers, primary peritoneal cancers, and occult ovarian cancers have all been reported. Several case series have reported a prevalence of malignant findings among mutation carriers undergoing risk-reducing oophorectomy. Among studies with 50 or more subjects, prevalence ranged from 2.3% to 11%.[282,293,360,437-442] Some of the variation in prevalence is likely due to differences in surgical technique, pathologic handling of the tissues, and age at RRSO. In addition to occult cancers, premalignant lesions have also been described in fallopian tube tissue removed for prophylaxis. In one series of 12 women with BRCA1 mutations undergoing risk-reducing surgery, 11 had hyperplastic or dysplastic lesions identified in the tubal epithelium. In several of the cases the lesions were multifocal.[279] These pathologic findings are consistent with the identification of germline BRCA1 and BRCA2 mutations in women affected with both tubal and primary peritoneal cancers.[67,71,441,443-446] One study suggests a causal relationship between early tubal carcinoma, or tubal intraepithelial carcinoma, and subsequent invasive serous carcinoma of the fallopian tube, ovary or peritoneum.[447] (Refer to the Pathology of ovarian cancer section of this summary for more information.)

These findings support the inclusion of fallopian tube cancers, which account for less than 1% of all gynecologic cancers in the general population, as a component of hereditary ovarian cancer syndrome and necessitate removal of the fallopian tubes at the time of risk-reducing surgery. There is clear evidence that RRSO must include routine collection of peritoneal washings and careful adherence to comprehensive pathologic evaluation of the entire adnexa using serial sectioning.[282,448,449]

The peritoneum, however, appears to remain at low risk for the development of a Müllerian-type adenocarcinoma, even after oophorectomy.[450-454] Of the 324 women from the Gilda Radner Familial Ovarian Cancer Registry who underwent risk-reducing oophorectomy, six (1.8%) subsequently developed primary peritoneal carcinoma. No period of follow-up was specified.[455] Among 238 individuals in the Creighton Registry with BRCA1/BRCA2 mutations who underwent risk-reducing oophorectomy, five subsequently developed intra-abdominal carcinomatosis (2.1%). Of note, all five of these women had BRCA1 mutations.[134] A study of 1,828 women with a BRCA1 or BRCA2 mutation found a 4.3% risk of primary peritoneal cancer at 20 years after RRSO.[135]

Given the current limitations of screening for ovarian cancer and the high risk of the disease in BRCA1 and BRCA2 mutation carriers, NCCN Guidelines recommend RRSO between the ages of 35 and 40 years or upon completion of childbearing, as an effective risk-reduction option. Optimal timing of RRSO must be individualized, but evaluating a woman's risk of ovarian cancer based on mutation status can be helpful in the decision-making process. In a large study of U.S. BRCA1 and BRCA2 families, age-specific cumulative risk of ovarian cancer at age 40 years was 4.7% for BRCA1 mutation carriers and 1.9% for BRCA2 mutation carriers.[456] In a combined analysis of 22 studies of BRCA1 and BRCA2 mutation carriers, risk of ovarian cancer for BRCA1 mutation carriers increased most sharply from age 40 years to age 50 years, while the risk for BRCA2 mutation carriers was low before age 50 years but increased sharply from age 50 years to age 60 years.[114] In a population-based study of BRCA mutations in ovarian cancer patients, patients with BRCA2 mutations had a significantly later age of onset than patients with BRCA1 mutations (57.3 years [range, 40–72] vs. 52.6 years [range, 31–78]).[8] In summary, women with BRCA1 mutations may consider RRSO for ovarian cancer risk reduction at a somewhat earlier age than women with BRCA2 mutations; however, women with BRCA2 mutations may still consider early RRSO for breast cancer risk reduction.

The role of concomitant hysterectomy at the time of RRSO is controversial in BRCA1/2 mutation carriers. There is concern that a small portion of the proximal fallopian tube remains when hysterectomy is not performed, thereby resulting in a residual increased risk of fallopian tube cancer. However, several studies that have examined fallopian tube cancers indicate that the vast majority of these cancers occur in the distal or midportion of the fallopian tube, suggesting that the occurrence of proximal fallopian tube cancer would be a very unlikely event. Some reports have suggested an increased incidence of uterine carcinoma in mutation carriers,[457] whereas others have not confirmed an elevated risk of serous uterine cancer.[165] A prospective study of 857 women suggested that any increased incidence of uterine cancer appeared to be among BRCA1 mutation carriers who used tamoxifen [458]; this was confirmed by the same group in a later study of 4,456 BRCA1/2 mutation carriers.[459] Even with tamoxifen use, the excess risk of endometrial cancer was small, with a 10-year cumulative risk of 2%.[459] In addition, the use of tamoxifen can now be minimized, given the options of raloxifene (which does not increase the risk of uterine cancer) and aromatase inhibitors for breast cancer prevention in postmenopausal women. Therefore, on the basis of the current understanding of the risk of uterine cancer in BRCA mutation carriers, there is not a singularly compelling reason to consider hysterectomy at the time of RRSO to reduce the risk of uterine cancer. Concomitant hysterectomy does offer the advantage of simplifying the hormone replacement regimen for BRCA mutation carriers who choose to take hormones. After hysterectomy, women can take estrogen alone (which does not increase the risk of breast cancer), without progestins, thereby eliminating the risk of postmenopausal bleeding.

Studies indicate that removal of the uterus is not necessary as a risk-reducing procedure. No increased BRCA mutation prevalence was seen among 200 Jewish women with endometrial carcinoma or 56 unselected women with uterine papillary serous carcinoma.[164,165] However, small studies have reported that uterine papillary serous carcinoma may be part of the BRCA-associated spectrum of disease.[457,460,461] The cumulative risk of endometrial cancer among BRCA mutation carriers with ER-positive breast cancer treated with tamoxifen may be an additional factor to consider when counseling this population about prophylactic hysterectomy.[458,462] Hysterectomy might also be considered in young, unaffected BRCA mutation carriers who may want to use HRT but for whom hysterectomy would offer a simplified regimen of estrogen alone. In counseling a BRCA mutation carrier about optimal risk-reducing surgical options, aggregate data suggest that the risk from residual tubal tissue after RRSO is the least compelling reason to suggest hysterectomy. Therefore, in the absence of tamoxifen use or other underlying uterine or cervical problems, hysterectomy is not a routine component of RRSO for BRCA carriers.

For women who are premenopausal at the time of surgery, the symptoms of surgical menopause (e.g., hot flashes, mood swings, weight gain, and genitourinary complaints) can cause a significant impairment in their quality of life. To reduce the impact of these symptoms, providers have often prescribed a time-limited course of systemic HRT after surgery. (Refer to the Hormone replacement therapy in BRCA1/BRCA2 mutation carriers section of this summary for more information.)

Studies have examined the effect of RRSO on quality of life (QOL). One study examined 846 high-risk women of whom 44% underwent RRSO and 56% had periodic screening.[463] Of the 368 BRCA1/BRCA2 mutation carriers, 72% underwent RRSO. No significant differences were observed in QOL scores (as assessed by the Short Form-36) between those with RRSO or screening or compared with the general population; however, women with RRSO had fewer breast and ovarian cancer worries (P < .001), more favorable cancer risk perception (P < .05) but more endocrine symptoms (P < .001) and worse sexual functioning (P < .05). Of note, 37% of women used HRT after RRSO, although 62% were either perimenopausal or postmenopausal.[463] Researchers then examined 450 premenopausal high-risk women who had chosen either RRSO (36%) or screening (64%). Of those in the RRSO group, 47% used HRT. HRT users (n = 77) had fewer vasomotor symptoms than nonusers (n = 87; P < .05), but they had more vasomotor symptoms than women in the screening group (n = 286). Likewise, women who underwent RRSO and used HRT had more sexual discomfort due to vaginal dryness and dyspareunia than those in the screening group (P < .01). Therefore, while such symptoms are improved via HRT use, HRT is not completely effective and additional research is warranted to address these important issues.

The long-term nononcologic effects of RRSO in BRCA1/BRCA2 mutation carriers are unknown. In the general population, RRSO has been associated with increased cardiovascular disease, dementia, death from lung cancer, and overall mortality.[464-468] When age at oophorectomy has been analyzed, the most detrimental effect has been seen in women who undergo RRSO before age 45 years and do not take estrogen-replacement therapy.[464] BRCA1/BRCA2 mutation carriers undergoing RRSO may have an increased risk of metabolic syndrome.[469] RRSO has also been associated with an improvement in short-term mortality in this population.[436] The benefits related to cancer risk reduction after RRSO are clear, but further data on the long-term nononcologic risks and benefits are needed.

Bilateral salpingectomy

Bilateral salpingectomy has been suggested as an interim procedure to reduce risk in BRCA mutation carriers.[470,471] There are no data available on the efficacy of salpingectomy as a risk-reducing procedure. The procedure preserves ovarian function and spares the premenopausal patient the adverse effects of a premature menopause. The procedure can be performed using a minimally invasive approach, and a subsequent bilateral oophorectomy could be deferred until the patient approaches menopause. While the data make a compelling argument that some pelvic serous cancers in BRCA mutation carriers originate in the fallopian tube, clearly, some cancers arise in the ovary. Furthermore, bilateral salpingectomy could give patients a false sense of security that they have eliminated their cancer risk as completely as if they had undergone a bilateral salpingo-oophorectomy. A small study of 14 young BRCA mutation carriers documented the procedure as feasible.[472] However, efficacy and impact on ovarian function was not assessed in this study. Future prospective trials are needed to establish the validity of the procedure as a risk-reducing intervention.

Chemoprevention

Oral contraceptives

OCs have been shown to have a protective effect against ovarian cancer in the general population.[473] Several studies including a large, multicenter, case-control study showed a protective effect,[390,474-477] while one population-based study from Israel failed to demonstrate a protective effect.[478]

There has been great interest in determining whether a similar benefit extends to women who are at increased genetic risk of ovarian cancer. A multicenter study of 799 ovarian cancer patients with BRCA1 or BRCA2 mutations, and 2,424 control patients without ovarian cancer but with a BRCA1 or BRCA2 mutation, showed a significant reduction in ovarian cancer risk with use of OCs (OR, 0.56; 95% CI, 0.45–0.71). Compared with never use of OCs, duration up to 1 year was associated with an OR of 0.67 (95% CI, 0.50–0.89). The OR for each year of OC use was 0.95 (95% CI, 0.92–0.97), with a maximum observed protection at 3 years to 5 years of use.[477] This study included women from a prior study by the same authors and confirmed the results of that prior study.[390] A population-based case-control study of ovarian cancer did not find a protective benefit of OC use in BRCA1 or BRCA2 mutation carriers, (OR, 1.07 for ≥5 years of use), although they were protective, as expected, among noncarriers (OR, 0.53 for ≥5 years of use).[478] A small, population-based, case-control study of 36 BRCA1 mutation carriers, however, observed a similar, protective effect in both mutation carriers and noncarriers (OR, approximately 0.5).[476] A multicenter study of subjects drawn from numerous registries observed a protective effect of OCs among the 147 BRCA1 or BRCA2 mutation carriers, with ovarian cancer compared with the 304 matched mutation carriers without cancer (OR, 0.62 for ≥6 years of use).[475] Finally, a meta-analysis of 18 studies including 13,627 BRCA mutation carriers, of whom 2,855 had breast cancer and 1,503 had ovarian cancer, reported a significantly reduced risk of ovarian cancer (summary relative risk, 0.50; 95% CI, 0.33–0.75) associated with OC use. The authors also reported significantly greater risk reductions with longer duration of OC use (36% reduction in risk for each additional 10 years of OC use). There was no association with breast cancer risk and use of OC pills formulated after 1975.[123]

Level of evidence: 3aii

(Refer to the Oral contraceptives section in the Reproductive factors section of this summary for a discussion of OC use and breast cancer in this population.)

Reproductive factors

It has been suggested that incessant ovulation, with repetitive trauma and repair to the ovarian epithelium, increases the risk of ovarian cancer. In epidemiologic studies in the general population, physiologic states that prevent ovulation have been associated with decreased risk of ovarian cancer. It has also been suggested that chronic overstimulation of the ovaries by luteinizing hormone plays a role in ovarian cancer pathogenesis.[479] Most of these data derive from studies in the general population, but some information suggests the same is true in women at high risk due to genetic predisposition.

Pregnancy

Among the general population, parity decreases the risk of ovarian cancer by 45% compared with nulliparity. Subsequent pregnancies appear to decrease ovarian cancer risk by 15%.[480] Earlier studies of women with BRCA1/BRCA2 mutations showed that parity decreases the risk of ovarian cancer.[478,481] In a large case-control study, parity was associated with a significant reduction in ovarian cancer risk in women with BRCA1 mutations, OR 0.67 (CI, 0.46–0.96).[477] For each birth, BRCA1 mutation carriers had an OR of 0.87 (CI, 0.79–0.95). In this same study, parity was associated with an increase in ovarian cancer risk in BRCA2 mutation carriers; however, there was no significant trend for each birth, OR 1.08 (CI, 0.90–1.29). Further studies are necessary to define the association of parity and risk of ovarian cancer in BRCA2 mutation carriers, but for BRCA1 carriers, each live birth significantly decreases risk of ovarian cancer, as it does in sporadic ovarian cancer.

Lactation and tubal ligation

In the general population, breast feeding is associated with a decrease in ovarian cancer risk.[482] In BRCA mutation carriers, data are limited. One study found no protective effect with breast feeding.[481] A case-control study among women with BRCA1 or BRCA2 mutations demonstrates a significant reduction in risk of ovarian cancer (OR, 0.39) for women who have had a tubal ligation. This protective effect was confined to those women with mutations in BRCA1 and persists after controlling for OC use, parity, history of breast cancer, and ethnicity.[474] A case-control study of ovarian cancer in Israel found a 40% to 50% reduced risk of ovarian cancer among women undergoing gynecologic surgeries (tubal ligation, hysterectomy, unilateral oophorectomy, ovarian cystectomy, excluding bilateral oophorectomy).[433] The mechanism of protection is uncertain. Proposed mechanisms of action include decreased blood flow to the ovary, resulting in interruption of ovulation and/or ovarian hormone production; occlusion of the fallopian tube, thus blocking a pathway for potential carcinogens; or a reduction in the concentration of uterine growth factors that reach the ovary.[483] (Refer to the PDQ summary on Prevention of Ovarian Cancer for information relevant to the general population.)

Oral contraceptives

Refer to the Oral contraceptives section in the Chemoprevention section of this summary for more information.

Management of Male BRCA Mutation Carriers

There are data to suggest that men with BRCA gene mutations have an increased risk of various cancers including male breast cancer and prostate cancer (see Table 5).[8,12,57,66,139,484] However, clinical guidelines to manage male carriers with BRCA mutations are based on consensus statements and expert opinions because information is limited.[13,85,485]

There have been suggestions that BRCA2-associated prostate cancers are associated with aggressive disease phenotype.[140-145] Specifically, two recent studies have reported the median survival of male BRCA2 carriers with prostate cancer in the range of 4 to 5 years.[143,144] Furthermore, mortality rate was reported as 60% at 5 years in one of these studies, compared with 2% to 8% reported in the recent European [486] and North American [487] PSA screening trials after comparable follow-up. The data have been more limited in BRCA1-associated prostate cancers, however a number of recent studies have suggested an aggressive disease phenotype as well.[140,142,145,488]

The benefits of PSA screening in BRCA carriers are unknown; however, there have been suggestions (based on very small studies) that PSA levels at prostate cancer diagnosis may be higher in carriers than noncarriers.[489,490] These findings suggest that PSA screening may be of potential utility in men with BRCA mutations, especially in view of the aggressive phenotype. Preliminary results of the IMPACT PSA screening study reported a PPV of 47.6% in 21 BRCA2 carriers undergoing biopsy on the basis of elevated PSA.[491] Because screening these men detected clinically significant prostate cancer, the authors suggest that these findings provide rationale for continued screening in such men; however, a survival benefit from such screening has not been shown. Ultimately, it is possible that information on BRCA mutation status in men may inform optimal screening and treatment strategies. Furthermore, recent data that the presence of a germline BRCA2 mutation is an independent prognostic factor for survival in prostate cancer led these authors to conclude that active surveillance may not be the optimal management strategy due to the aggressive disease phenotype.[144]

Screening for male breast cancer in BRCA mutation carriers as suggested by the NCCN clinical practice guidelines [85] includes breast self-exam training and education, clinical breast exam every 6 to 12 months, and consideration of a baseline mammogram. Annual mammogram is a consideration with the presence of gynecomastia or parenchymal/glandular breast density on baseline study. Furthermore, NCCN recommends prostate cancer screening for BRCA2 carriers starting at age 40 years.[85]

Reproductive Considerations in BRCA Mutation Carriers

Refer to the Prenatal diagnosis and preimplantation genetic diagnosis section in the Psychosocial Issues in Inherited Breast Cancer Syndromes section of this summary for more information.

Treatment Strategies

Breast cancer

Prognosis of BRCA1- and BRCA2-related breast cancer

BRCA1-related breast cancer

The distinct features of BRCA1-associated breast tumors are important in prognosis. In addition, there appears to be accelerated growth in BRCA1-associated breast cancer, which is suggested by high-proliferation indices and absence of the expected correlation of tumor size with lymph node status.[492] These pathological features are associated with a worse prognosis in breast cancer, and early studies suggested that BRCA1 mutation carriers with breast cancer may have a poorer prognosis compared with sporadic cases.[230,493,494] These studies particularly noted an increase in ipsilateral and contralateral second primary breast cancers in BRCA1 and BRCA2 mutation carriers.[495-497] (Refer to the Contralateral breast cancer in BRCA mutation carriers section of this summary for more information.) A retrospective cohort study of 496 AJ breast cancer patients from two centers compared the relative survival among 56 BRCA1/BRCA2 mutation carriers followed for a median of 116 months. BRCA1 mutations were independently associated with worse disease-specific survival. The poorer prognosis was not observed in women who received chemotherapy.[498] A large population-based study of incident cases of breast cancer among women in Israel failed to find a difference in OS for carriers of BRCA1 founder mutations (n = 76) compared with noncarriers (n = 1,189).[499] Similar findings were seen in a European cohort with no differences in disease-free survival in BRCA1-associated breast cancers.[500] Subsequently, a prospective cohort study of 3,220 women from North America and Australia with incident breast cancer (including 93 BRCA1 carriers and 71 BRCA2 carriers) who were followed up for a mean of 7.9 years reported similar outcomes among BRCA1/2 carriers and those with sporadic disease.[501] However, results were based on chemotherapy regimens used in the late 1990s and did not adjust for surgical approach (lumpectomy vs. mastectomy) and effect of oophorectomy.

A group of researchers reported the results of BRCA1/2 testing in 77 unselected patients with triple-negative breast cancer. Of these, 15 (19.5%) had either a germline BRCA1 (n = 11; 14%) or BRCA2 (n = 3; 4%) mutation or a somatic BRCA1 (n = 1) mutation. The median age at cancer diagnosis was 45 years in BRCA1 mutation carriers and 53 years in noncarriers (P = .005). Interestingly, this study also demonstrated a lower risk of relapse in those with BRCA1 mutation–associated triple-negative breast cancer than in nonmutated triple-negative breast cancer, although this study was limited by its size.[244] A second study examining clinical outcome in BRCA1-associated versus non-BRCA1-associated triple-negative breast cancer showed no difference, although there was a trend toward more brain metastases in those with BRCA1-associated breast cancer. In both of these studies, all but one BRCA1 mutation carrier received chemotherapy.[245]

A Polish study of 3,345 patients younger than 50 years with stages I through III breast cancer studied the impact of a BRCA1 mutation on prognosis. In this cohort, 233 patients (7%) carried one of three Polish BRCA1 founder mutations (5382insC, C61G, or 4154delA). BRCA1 carriers were younger and more frequently ER-negative and HER2/neu-negative. Ten-year survival was similar (80.9% in BRCA1 carriers and 82.2% in noncarriers). Oophorectomy was associated with improved survival in BRCA1 carriers (HR, 0.30; 95% CI 0.12–0.75).[502]

In summary, BRCA1-associated tumors appear to have a prognosis similar to sporadic tumors despite having clinical, histopathologic, and molecular features, which indicate a more aggressive phenotype. BRCA1 mutation carriers who do not receive chemotherapy may have a worse prognosis. However, because most BRCA1-associated breast cancers are triple negative, they are usually treated with adjuvant chemotherapy. Work is ongoing to determine whether BRCA1-associated breast cancers should receive different therapy than sporadic tumors. (Refer to the Role of BRCA1 and BRCA2 in response to systemic therapy section of this summary for more information.)

BRCA2-related breast cancer

Early studies of the prognosis of BRCA2 associated breast cancer have not shown substantial differences in comparison with sporadic breast cancer.[499,503-505] A small study reported statistically significant higher OS in BRCA2 mutation carriers with metastatic breast cancer.[500]

Systemic therapy

Role of BRCA1 and BRCA2 in response to systemic therapy

A growing body of preclinical and clinical literature suggests a differential response of BRCA-related breast cancers to systemic chemotherapy. This is based on the emerging understanding of the functions of these genes in response to DNA damage and mitotic spindle machinery control. As several chemotherapeutic agents target either DNA or mitotic spindle structural integrity, the lack of BRCA functions could alter response to these agents. Intact BRCA1 and BRCA2 are important in DNA repair by homologous recombination. Preclinical studies of BRCA1- and BRCA2-deficient cell lines have suggested increased sensitivity to drugs that cause DNA damage that is repaired by homologous recombination, such as cisplatin, carboplatin and mitomycin C.[506,507] Conversely, intact BRCA1 may be important for spindle poisons, such as taxanes, to be effective.[508,509] Preclinical models suggest decreased sensitivity to these drugs in mutated cell lines.[510,511]

Evidence of the role of BRCA1/BRCA2 mutations in humans is evolving. A number of small studies have suggested increased clinical response rates, particularly in BRCA1 mutation carriers, but design limitations make it difficult to use these studies to guide clinical recommendations.

Retrospective and prospective studies [512-516] have suggested a higher-than-expected response rate to chemotherapy in BRCA1 mutation carriers receiving neoadjuvant chemotherapy for breast cancer, especially when using cisplatin.[514] Several studies have been published regarding the Polish experience on the use of preoperative chemotherapy in BRCA1 mutation carriers. The largest report [514] includes data on 102 BRCA1 mutation carriers of which 51 were described in two prior studies.[517,512] Women were identified from a registry of 6,903 patients. Those with a Polish founder mutation in BRCA1 (5382insC, C61G, or 4153delA) who had also received preoperative chemotherapy were included. Of these 102 women, 22% had a pathologic complete response (pCR). Twelve women received cisplatin chemotherapy as part of a clinical trial of whom 10 had a pCR (83%). All other patients were examined retrospectively. Of these, 14 received cyclophosphamide, methotrexate, and fluorouracil with one pCR (7%), 25 received doxorubicin and docetaxel with two pCRs (8%), and 51 received doxorubicin and cyclophosphamide with 11 pCRs (22%). To place this in the context of other available data, several retrospective studies in BRCA1 and BRCA2 mutation carriers typically treated with anthracycline-based chemotherapy have demonstrated clinical complete response rates of 46% to 90% after preoperative chemotherapy,[513,515] particularly in BRCA1 mutation carriers.[516] A trial of preoperative cisplatin in triple-negative breast cancer patients demonstrated a pCR of 22%; however, both BRCA1 mutation carriers in the study had a pCR.[518]

A small study reported a statistically significant higher sensitivity to first-line treatment in BRCA2 mutation carriers with metastatic breast cancer than in those with sporadic metastatic cancer; conversely, no statistically significant differences were observed for BRCA1 carriers with metastatic breast cancer.[500] No data directly compare different types of chemotherapy in BRCA1 and BRCA2 mutation carriers. However, in a small study of 20 BRCA1 mutation carriers with metastatic breast cancer, there was an overall response rate of 80% to cisplatin therapy.[519] Further studies are evaluating the role of platinums in BRCA1- and BRCA2-associated metastatic cancer.

Thus, the preclinical and clinical data suggesting improved chemotherapy response rates in BRCA1-associated breast cancer are consistent with the emerging understanding of BRCA1 function in DNA-damage response and cell-cycle regulation. While these findings raise the possibility that germline status may influence treatment choices, there is insufficient evidence at this time to support treating mutation carriers with different regimens in the adjuvant and neoadjuvant setting.

Another specific process to exploit in BRCA1/BRCA2-deficient tumors is the poly (ADP-ribose) polymerase (PARP) pathway. Whereas BRCA1 and BRCA2 are active in the repair of double-stranded DNA breaks by homologous recombination, PARP is involved in the repair of single-stranded breaks by base excision repair. It was hypothesized that inhibiting base excision repair in BRCA1- or BRCA2-deficient cells would lead to enhanced cell death as two separate repair mechanisms would be compromised—the concept of synthetic lethality. In vitro studies have shown that PARP inhibition kills BRCA mutant cells with high specificity.[217,520]

PARP inhibitors quickly entered clinical trials. A phase I study of an oral PARP inhibitor called olaparib has demonstrated tolerability (with minimal side effects) and activity in BRCA1 and BRCA2 mutation carriers with breast cancer, ovarian cancer, and prostate cancer.[521] Phase II trials in breast cancer have confirmed tolerability and efficacy of olaparib in mutation carriers.[522,523] Two sequential cohorts of 27 patients, each receiving 400 mg twice daily of olaparib and 100 mg twice daily of olaparib, respectively, were examined. The women had received a median of three prior chemotherapeutic regimens. Responses were seen in both groups. In the 400 mg twice daily group, 41% (11 of 27) of patients had a RECIST-defined response, and another 44% (12 of 27) had stable disease. In the 100 mg twice daily group, 22% (6 of 27) had responses, and 44% (12 of 27) had stable disease. Although the two dose levels cannot be directly compared because they were not randomized, more responses were seen in the higher dose cohort. Several other PARP inhibitors are in development.

Preclinical models suggest that the combination of PARP inhibitors and chemotherapy may be synergistic;[524,525] however, such synergy may come at the expense of toxicity. The results of ongoing and recently completed clinical trials are awaited with interest.

(Refer to the Systemic therapy section in the Ovarian Cancer Treatment Strategies section of this summary for more information.)

Local therapy

Breast conservation therapy for BRCA1/BRCA2 mutation carriers

While lumpectomy plus radiation therapy has become standard local-regional therapy for women with early-stage breast cancer, its use in women with a hereditary predisposition for breast cancer who do not choose immediate bilateral mastectomy is more complicated. Initial concerns about the potential for therapeutic radiation to induce tumors or cause excess toxicity in BRCA1/BRCA2 mutation carriers were unfounded.[526-528] Despite this, an increased rate of second primary breast cancer exists, which could impact treatment decisions.

Because of the established increased risk of second primary breast cancers, which may be up to 60% in younger women with BRCA1 mutations,[497] some BRCA1/BRCA2 mutation carriers choose bilateral mastectomy at the time of their initial cancer diagnosis. (Refer to the Contralateral breast cancer in BRCA mutation carriers section of this summary for more information.) However, several studies support the use of breast conservation therapy as a reasonable option to treat the primary tumor.[529-531] The risk of ipsilateral recurrence at 10 years has been estimated to be between 10% to 15% and is similar to that seen in noncarriers.[497,529-532] Studies with longer follow-up demonstrate risks of ipsilateral breast events at 15 years to be as high as 24%, largely due to ipsilateral second breast cancers (rather than relapse of the primary tumor).[529,531] Although not entirely consistent across studies, radiation therapy, chemotherapy, oophorectomy, and tamoxifen are associated with a decreased risk of ipsilateral events,[529-532] as is the case in sporadic breast cancer. The risk of contralateral breast cancer does not appear to be different in women undergoing breast conservation therapy versus unilateral mastectomy, suggesting no added risk of contralateral breast cancer from scattered radiation.[529] This finding is supported by a population-based case-control study of women diagnosed with breast cancer before the age of 55 years.[533] All women were genotyped for BRCA1/2. Although there was a significant fourfold risk of contralateral breast cancer in carriers compared with noncarriers, carriers who were exposed to radiation therapy for the first primary were not at increased risk of contralateral breast cancer compared with carriers who were not exposed. (Refer to the Mammography section for more information about radiation and breast cancer risk.) Finally, no difference in OS at 15 years has been seen between BRCA1/BRCA2 mutation carriers choosing breast conservation therapy and carriers choosing mastectomy.[529]

Level of evidence: 3a

Second malignancies

Contralateral breast cancer in BRCA mutation carriers

As early as 1995, the Breast Cancer Linkage Consortium estimated the risk of contralateral breast cancer (CBC) in BRCA1 mutation carriers to be as high as 60% by age 60 years.[534] This report has been followed by several retrospective studies of various cohorts of women with hereditary patterns of breast cancer in both the United States and Europe. One retrospective cohort study reviewed the records of 91 AJ women diagnosed with breast cancer before the age of 42 years, 30 of whom had a deleterious BRCA1 or BRCA2 mutation.[535] At a median follow-up of 63 months, the rate of CBC was 40% in the mutation carriers compared with 8.2% among noncarriers. Carriers had a shorter median interval between cancers than noncarriers (36 months vs. 63.9 months). The same group reported 5-, 10-, and 15-year probabilities of CBC of 11.9%, 37.6% and 53.2%, respectively, among 87 mutation carriers.[536] Rates of CBC in this clinical cohort did not differ by mutation type (BRCA1 vs. BRCA2) or by age at first diagnosis. A case-control study from the Netherlands compared rates of CBC between 49 women with BRCA1-related breast cancer and 196 breast cancer cases not known to have a BRCA1/BRCA2 mutation (sporadic controls).[230] At 5 years of follow-up, rates of CBC were 20.4% among mutation carriers versus 5.6% among the controls. In an expanded cohort of BRCA1-related breast cancer patients, the risk of CBC was inversely correlated with age at first diagnosis, with the majority of cases of CBC occurring among women whose first breast cancer was diagnosed at or before age 50 years.[537] A similar analysis matching 28 BRCA2 mutation–positive cases with 112 sporadic controls found a fivefold increase in CBC among cases (25% vs. 4.5%).[538] A larger study of members of BRCA1/BRCA2 families in the Netherlands reported similar 10-year risks of CBC for women from BRCA1 and BRCA2 families (34.2% and 29.2%).[539] In another study, 127 patients with early-onset breast cancer (aged ≤42 years) who had been treated with breast-conserving therapy, were genotyped for mutations in BRCA1 and BRCA2. At a median follow-up of 12 years, the rate of CBC among the 22 mutation-positive patients was 42% compared with 9% in the noncarriers.[495] A similar analysis from the Institut Curie in Paris reported a rate of CBC of 37% among mutation carriers compared with 7.3% in noncarriers at a median follow-up of 8.75 years.[540]

In a larger cohort of breast cancer patients (n = 336) from families with documented BRCA1/BRCA2 mutations and 9.2 years of follow-up, the rate of CBC was 28.9% at a mean interval of 5.5 years. Prior oophorectomy was associated with a 59% reduction in the risk of CBC.[541] Another case-control study of mutation carriers and noncarriers identified through ascertainment of women with bilateral breast cancer found that systemic adjuvant chemotherapy reduced CBC risk among mutation carriers (RR, 0.5; 95% CI, 0.2–1.0). Tamoxifen was associated with a nonsignificant risk reduction (RR, 0.7; 95% CI, 0.3–1.8). Similar risk reduction was seen in noncarriers; however, given the higher absolute CBC risk in carriers, there is potentially a greater impact of adjuvant treatment in risk reduction.[532] A high concordance in estrogen receptor status and tumor grade was reported among women from a registry of BRCA1/BRCA2 carriers who had bilateral breast cancer.[542] The German Consortium for Hereditary Breast and Ovarian Cancer estimated the risk of CBC in members of BRCA1 and BRCA2 mutation–positive families. At 25 years after the first breast cancer, the risk of CBC was close to 50% in both BRCA1 and BRCA2 families. The risk was also inversely correlated with age in this study, with the highest risks seen in women whose first breast cancer was before age 40 years.[497] A comparison of 655 women with BRCA1/BRCA2 mutations undergoing breast-conserving therapy versus those undergoing mastectomy noted that both treatment groups experienced high rates of CBC, exceeding 50% by 20 years of follow up. Rates were significantly higher among women with BRCA1 mutations compared with those with BRCA2 mutations, and among women whose first breast cancer occurred at or before age 35 years.[529] The WECARE study, a large population-based nested case-control study of CBC, reported a 10-year risk of CBC among BRCA1/BRCA2 mutation carriers of 15.9%, compared with a risk of 4.9% among noncarriers. Risks were also inversely related to age at first diagnosis in this study.[543]

Thus, despite differences in study design, study sites, and sample sizes, the data on CBC among women with BRCA1/BRCA2 mutations show several consistent findings:

  • The risk at all time points studied is significantly higher than that among sporadic controls.

  • The risk continues to rise with time since first breast cancer, and reaches 20% to 30% at 10 years of follow up, and 40% to 50% at 20 years in most studies.

  • Some, but not all, studies show an excess of CBC among BRCA1 carriers compared with BRCA2 carriers.

  • The risk of CBC is greatest among women whose first breast cancer occurs at a young age.

Chemoprevention

Refer to the Chemoprevention section of this summary for information about the use of tamoxifen as a risk-reduction strategy for CBC in BRCA mutation carriers.

Ovarian cancer

Prognosis of BRCA1- and BRCA2-related ovarian cancer

Despite generally poor prognostic factors, several studies have found an improved survival among ovarian cancer patients with BRCA mutations.[277,287,544-550] A nationwide, population-based, case-control study in Israel found 3-year survival rates to be significantly better for ovarian cancer patients with BRCA founder mutations, compared with controls.[545] Five-year follow-up in the same cohort showed improved survival for carriers of both BRCA1 and BRCA2 mutations (54 months) versus noncarriers (38 months), which was most pronounced for women with stages III and IV ovarian cancer and for women with high-grade tumors.[551] In a U.S. study of AJ women with ovarian cancer, those with BRCA mutations had a longer median time to recurrence and an overall improved survival, compared with both AJ women with ovarian cancer who did not have a BRCA mutation and two large groups of advanced-stage ovarian cancer clinical trial patients.[548] In a retrospective U.S. hospital-based study, Ashkenazi BRCA mutation carriers had a better response to platinum-based chemotherapy, as measured by response to primary therapy, disease-free survival, and OS, compared with sporadic cases.[546] Similarly, a significant survival advantage was seen in a case-control study among women with non-AJ BRCA mutations.[552] A study from the Netherlands also showed a better response to platinum-based primary chemotherapy in 112 BRCA1/2 carriers than in 220 sporadic ovarian cancer patients.[553] A U.S. population-based study showed improvement in OS in BRCA2, but not in BRCA1, carriers.[554] However, the study included only 12 BRCA2 mutation carriers and 20 BRCA1 mutation carriers. Significantly better OS and progression-free survival were observed in 29 BRCA2 mutation–positive high-grade serous ovarian cancer cases (20 germline, 9 somatic) from The Cancer Genome Atlas study compared with BRCA mutation–negative cases. BRCA1 mutations were not significantly associated with prognosis.[555] Furthermore, a pooled analysis of 26 observational studies that included 1,213 BRCA mutation carriers and 2,666 noncarriers with epithelial ovarian cancer showed more favorable survival in mutation carriers (BRCA1: HR, 0.73; 95% CI, 0.64–0.84; P < .001; BRCA2: HR, 0.49; 95% CI, 0.39–0.61; P < .001).[276] Thus, 5-year survival in both BRCA1 and BRCA2 carriers with epithelial ovarian cancers was better than that observed in noncarriers, with BRCA2 carriers having the best prognosis. A study in Japanese patients found a survival advantage in stage III BRCA1-associated ovarian cancers treated with cisplatin regimens compared with nonhereditary cancers treated in a similar manner.[547]

In contrast, several studies have not found improved OS among ovarian cancer patients with BRCA mutations.[493,556-558] The largest of these studies involved a large series of unselected Canadian and U.S. patients who were tested for BRCA1 and BRCA2 mutations. At 3 years, the presence of a mutation was associated with a better prognosis, but at 10 years, there was no longer a difference seen in prognosis.[559] Furthermore, one study suggested that there was worse survival in ovarian cancer patients with a family history.[557]

Compelling data suggest a short-term survival advantage in BRCA mutation carriers. However, long-term outcomes are yet to be established. Survival in AJ ovarian cancer patients with BRCA1 or BRCA2 founder mutations does seem to be improved;[276,555] however, further large studies in other populations with appropriate controls are needed to determine whether this survival advantage applies more broadly to all BRCA cancers.

Systemic therapy

The molecular mechanisms that explain the improved prognosis in hereditary BRCA-associated ovarian cancer are unknown but may be related to the function of BRCA genes. BRCA genes play an important role in cell-cycle checkpoint activation and in the repair of damaged DNA via homologous recombination.[560,561] Deficiencies in homologous repair can impair the cells’ ability to repair DNA cross-links that result from certain chemotherapy agents, such as cisplatin. Preclinical data has demonstrated BRCA1 impacts chemosensitivity in breast cancer and ovarian cancer cell lines. Reduced BRCA1 protein expression has been shown to enhance cisplatin chemosensitivity.[507] Patients with BRCA-associated ovarian cancer have shown improved responses to both first-line and subsequent platinum-based chemotherapy, compared with patients with sporadic cancers, which may contribute to their better outcome.[546,549]

PARP pathway inhibitors are currently being studied for the treatment of BRCA1- or BRCA2-deficient ovarian cancers. (Refer to the Role of BRCA1 and BRCA2 in response to systemic therapy section in the Breast Cancer Treatment Strategies section of this summary for more information about PARP inhibitors.) While PARP is involved in the repair of single-stranded breaks by base excision repair, BRCA1 and BRCA2 are active in the repair of double-stranded DNA breaks by homologous combination. Therefore, it was hypothesized that inhibiting base excision repair with PARP inhibition in BRCA1- or BRCA2-deficient tumors leads to enhanced cell death, as two separate repair mechanisms would be compromised—the concept of synthetic lethality.

A phase I study of olaparib, an oral PARP inhibitor, demonstrated tolerability (with minimal side effects) and activity in BRCA1 and BRCA2 mutation carriers with ovarian, breast, and prostate cancers.[521] A phase II trial of two different doses of olaparib demonstrated tolerability and efficacy in recurrent ovarian cancer patients with BRCA1 or BRCA2 mutations.[523] The overall response rate was 33% (11 of 33 patients) in the cohort receiving 400 mg twice daily and 13% (3 of 24 patients) in the cohort receiving 100 mg twice daily. The most frequent side effects were mild nausea and fatigue. Olaparib appears to be most effective in patients who are platinum-sensitive.[562] In addition to ovarian cancer patients with germline BRCA1 or BRCA2 mutations, PARP inhibitors also may be useful in ovarian cancer patients with somatic BRCA1 or BRCA2 mutations or with epigenetic silencing of the genes.[563]

Several additional phase II studies have been published that examined PARP inhibitors in ovarian cancer. In one study, women with BRCA1/2 mutations and recurrent ovarian cancer were randomly assigned to receive liposomal doxorubicin (Doxil) (n = 33), versus olaparib at 200 mg twice daily (n = 32), versus olaparib at 400 mg twice daily (n = 32). This study did not show a difference in progression-free survival between the groups, which was the primary endpoint.[564] Of interest, the liposomal doxorubicin arm had a higher response rate than anticipated, consistent with other studies demonstrating that BRCA1/2-associated ovarian cancers may be more sensitive to liposomal doxorubicin than are sporadic ovarian cancers.[565,566] Another study demonstrated significant responses to olaparib in recurrent ovarian cancer patients, including patients with a BRCA1/2 mutation (objective response rate [ORR], 41%) and patients without a BRCA1/2 mutation (ORR, 24%).[567] This study emphasizes that certain sporadic ovarian cancers, particularly those of high-grade serous histology, may have properties similar to BRCA1/2 mutation–related tumors.

Another study examined the role of maintenance therapy with the PARP inhibitor olaparib in platinum-sensitive recurrent ovarian cancer (not restricted to BRCA1/2 mutation carriers). In this randomized controlled trial, those who received olaparib maintenance therapy had an improvement in progression-free survival with an HR of 0.35. In BRCA1/2 mutation carriers, the HR was approximately 0.1.[568]

Level of evidence: 3dii

Second malignancies

Breast cancer

Two genetic registry–based studies have recently explored the risk of primary breast cancer after BRCA-related ovarian cancer. In one study, 164 BRCA1/2 carriers with primary epithelial ovarian, fallopian tube or primary peritoneal cancer were followed for subsequent events.[569] The risk of metachronous breast cancer at 5 years after a diagnosis of ovarian cancer was lower than previously reported for unaffected BRCA1/2 carriers. In this series, OS was dominated by ovarian cancer-related deaths. A similar study compared the risk of primary breast cancer in BRCA-related ovarian cancer patients and unaffected carriers.[570] The 2-year, 5-year, and 10-year risks of primary breast cancer were all statistically significantly lower in patients with ovarian cancer. The risk of contralateral breast cancer among women with a unilateral breast cancer before their ovarian cancer diagnosis was also lower than in women without ovarian cancer, although the difference did not reach statistical significance. These studies suggest that treatment for ovarian cancer, namely oophorectomy and platinum-based chemotherapy, may confer protection against subsequent breast cancer.

Other High-Penetrance Syndromes Associated with Breast and/or Ovarian Cancer

Lynch syndrome

Lynch syndrome (LS) is characterized by autosomal dominant inheritance of susceptibility to predominantly right-sided colon cancer, endometrial cancer, ovarian cancer, and other extracolonic cancers (including cancer of the renal pelvis, ureter, small bowel, and pancreas), multiple primary cancers, and a young age of onset of cancer.[571] The condition is caused by germline mutations in the MMR genes, which are involved in repair of DNA mismatch mutations.[572] The MLH1 and MSH2 genes are the most common susceptibility genes for LS, accounting for 80% to 90% of observed mutations,[573,574] followed by MSH6 and PMS2.[575-580] (Refer to the Lynch syndrome (LS) section in the PDQ summary on Genetics of Colorectal Cancer for more information about this syndrome.)

The lifetime risk of ovarian carcinoma in females with LS is estimated to be as high as 12%, and the reported RR of ovarian cancer has ranged from 3.6 to 13, based on families ascertained from high-risk clinics with known or suspected LS.[581-586] Characteristics of LS-associated ovarian cancers may include overrepresentation of the International Federation of Gynecology and Obstetrics stages 1 and 2 at diagnosis (reported as 81.5%), underrepresentation of serous subtypes (reported as 22.9%), and a better 10-year survival (reported as 80.6%) than reported both in population-based series and in BRCA mutation carriers.[587,588]

The issue of breast cancer risk in LS has been controversial. Retrospective studies have been inconsistent, but several have demonstrated microsatellite instability in a proportion of breast cancers from individuals with LS;[589-592] one of these studies evaluated breast cancer risk in individuals with LS and found that it is not elevated.[592] However, the largest prospective study to date of 446 unaffected mutation carriers from the Colon Cancer Family Registry [593] who were followed for up to 10 years reported an elevated SIR of 3.95 for breast cancer (95% CI, 1.59–8.13; P = .001).[593] The same group subsequently analyzed data on 764 MMR gene mutation carriers with a prior diagnosis of colorectal cancer. Results showed that the 10-year risk of breast cancer following colorectal cancer was 2% (95% CI, 1%–4%) and that the SIR was 1.76 (95% CI, 1.07–2.59).[594] However, further studies are needed to define absolute risks and age distribution before surveillance guidelines for breast cancer can be developed for MMR mutation carriers.

Li-Fraumeni syndrome

Breast cancer is also a component of the rare Li-Fraumeni syndrome (LFS) (OMIM), in which germline mutations of the TP53 gene (OMIM) on chromosome 17p have been documented.[595] This syndrome is characterized by premenopausal breast cancer in combination with childhood sarcoma, brain tumors, leukemia, and adrenocortical carcinoma.[596,597] Tumors in LFS families tend to occur in childhood and early adulthood, and often present as multiple primaries in the same individual. Evidence supports a genotype-phenotype correlation, with an association of the location of the mutation, the kind of cancer that develops, and the age of onset.[598] Brain and adrenal gland tumors were associated with specific sites of missense mutations. Age at onset of breast cancer was 34.6 years in families with a TP53 mutation compared with 42.5 years in those families without a mutation. A germline mutation in the TP53 gene has been identified in more than 50% of families exhibiting this syndrome, and inheritance is autosomal dominant, with a penetrance of at least 50% by age 50 years.

Germline TP53 mutations were identified in 17% (n = 91) of 525 samples submitted to City of Hope laboratories for clinical TP53 testing. All families with a TP53 mutation had at least one family member with a sarcoma, breast cancer, brain cancer, or adrenocortical cancer (core cancers). In addition, all eight individuals with a choroid plexus tumor had a TP53 mutation, as did 14 of the 21 individuals with childhood adrenocortical cancer. In women aged 30 to 49 years who had breast cancer but no family history of other core cancers, no TP53 mutations were found. TP53 mutations are uncommon in women with breast cancer before age 30 years with no other indications for TP53 screening (e.g., a family history of sarcoma). In three studies, the numbers of women with TP53 mutations were 0 (of 95), 1 (of 14), and 2 (of 52).[599-601]

Located on chromosome 17p, TP53 encodes a 53kd nuclear phosphoprotein that binds DNA sequences and functions as a negative regulator of cell growth and proliferation in the setting of DNA damage. It is also an active component of programmed cell death.[602] Inactivation of the TP53 gene or disruption of the protein product is thought to allow the persistence of damaged DNA and the possible development of malignant cells.[597] Evidence also exists that patients treated for a TP53-related tumor with chemotherapy or radiation therapy may be at risk of a treatment-related second malignancy. Germline mutations in TP53 are thought to account for fewer than 1% of breast cancer cases.[603] TP53-associated breast cancer is often HER2/neu-positive, in addition to being ER-positive, PR-positive, or both.[604-606]

Screening for breast cancer with annual MRI is recommended;[85] additional screening for other cancers has been studied and is evolving.[607,608]

Cowden syndrome

One of the more than 50 cancer-related genodermatoses, Cowden syndrome (OMIM) is characterized by multiple hamartomas, an excess of breast cancer, gastrointestinal malignancies, endometrial cancer, and thyroid disease, both benign and malignant.[609,610] Lifetime breast cancer risk is estimated to be between 25% and 50% among women with Cowden syndrome.[611] Other studies have reported risks as high as 85%;[612-614] however, there are concerns regarding selection bias in these studies. As in other forms of hereditary breast cancer, onset is often at a young age and may be bilateral.[615] Skin manifestations include multiple trichilemmomas, oral fibromas and papillomas, and acral, palmar, and plantar keratoses. History or observation of the characteristic skin features raises a suspicion of Cowden syndrome. Central nervous system manifestations include macrocephaly, developmental delay, and dysplastic gangliocytomas of the cerebellum.[616,617] Germline mutations in the PTEN gene (OMIM), which is located on chromosome 10q23 and encodes a tyrosine phosphatase protein with homology to tensin, are responsible for Cowden syndrome. Loss of heterozygosity at the PTEN locus observed in a high proportion of related cancers suggests that PTEN functions as a tumor suppressor gene. Its defined enzymatic function indicates a role in maintenance of the control of cell proliferation.[618] Disruption of PTEN appears to occur late in tumorigenesis and may act as a regulatory molecule of cytoskeletal function. Although PTEN mutations, which are estimated to occur in 1 in 200,000 individuals,[610] account for a small fraction of hereditary breast cancer, the characterization of PTEN function will provide valuable insights into the signal pathway and the maintenance of normal cell physiology.[610,619] (Refer to the Major Genes section in the PDQ summary on Genetics of Colorectal Cancer for more information about Cowden syndrome.)

Peutz-Jeghers syndrome (PJS)

PJS is an early-onset autosomal dominant disorder characterized by melanocytic macules on the lips, the perioral region, and buccal region; and multiple gastrointestinal polyps, both hamartomatous and adenomatous.[620-622] Germline mutations in the STK11 gene at chromosome 19p13.3 have been identified in the vast majority of PJS families.[623-627] The most common cancers in PJS are gastrointestinal. However, other organs are at increased risk of developing malignancies. For example, the cumulative risks have been estimated to be 32% to 54% for breast cancer [628-630] and 21% for ovarian cancer.[628] A systematic review found a lifetime cumulative cancer risk, all sites combined, of up to 93% in patients with PJS.[631] Table 10 shows the cumulative risk of these tumors. The high cumulative risk of cancers in PJS has led to the various screening recommendations summarized in the table of Published Recommendations for Diagnosis and Surveillance of Peutz-Jeghers Syndrome (PJS) in the PDQ summary on Genetics of Colorectal Cancer.

Although the risk of malignancy appears to be exceedingly high in individuals with PJS based on the published literature, the possibility that selection and referral biases have resulted in over-estimates of these risks should be considered.

Table 10. Cumulative Cancer Risks in Peutz-Jeghers Syndrome Up To Specified Agea
Site Age (y) Cumulative Risk (%)b Reference(s) 
Any cancer60–7037–93[627-630,632,633]
GI cancerc,d60–7038–66[629,630,632,633]
Gynecological cancer60–7013–18[629,630]
Per origin
Stomach6529[628]
Small bowel6513[628]
Colorectum6539[628,629]
Pancreas65–7011–36[628,629]
Lung65–707–17[628-630]
Breast60–7032–54[628-630]
Uterus659[628]
Ovary6521[628]
Cervixe6510[628]
Testese659[628]

GI = gastrointestinal.
aReprinted with permission from Macmillan Publishers Ltd: Gastroenterology [631], copyright 2010.
bAll cumulative risks were increased compared with the general population (P < .05), with the exception of cervix and testes.
cGI cancers include colorectal, small intestinal, gastric, esophageal, and pancreatic.
dWesterman et al.: GI cancer does not include pancreatic cancer.[632]
eDid not include adenoma malignum of the cervix or Sertoli cell tumors of the testes.

Peutz-Jeghers gene(s)

PJS is caused by mutations in the STK11 (also called LKB1) tumor suppressor gene located on chromosome 19p13.[624,625] Unlike the adenomas seen in familial adenomatous polyposis, the polyps arising in PJS are hamartomas. Studies of the hamartomatous polyps and cancers of PJS show allelic imbalance (loss of heterozygosity [LOH]) consistent with the two-hit hypothesis, demonstrating that STK11 is a tumor suppressor gene.[634,635] However, heterozygous STK11 knockout mice develop hamartomas without inactivation of the remaining wild-type allele, suggesting that haploinsufficiency is sufficient for initial tumor development in PJS.[636] Subsequently, the cancers that develop in STK11 +/- mice do show LOH;[637] indeed, compound mutant mice heterozygous for mutations in STK11 +/- and homozygous for mutations in TP53 -/- have accelerated development of both hamartomas and cancers.[638]

Germline mutations of the STK11 gene represent a spectrum of nonsense, frameshift, and missense mutations, and splice-site variants and large deletions.[623,629] Approximately 85% of mutations are localized to regions of the kinase domain of the expressed protein, and no germline mutations have been reported in exon 9. No strong genotype-phenotype correlations have been identified.[629]

One gene (STK11) has been unequivocally demonstrated to cause PJS. Although earlier estimates using direct DNA sequencing showed a 50% mutation detection rate in STK11, studies adding techniques to detect large deletions have found mutations in up to 94% of individuals meeting clinical criteria for PJS.[623,631,639] Given the results of these studies, it is unlikely that other major genes cause PJS.

De novo mutation rate

Until the 1990s, the diagnosis of genetically inherited breast and ovarian cancer syndromes was based on clinical manifestations and family history. Now that some of the genes involved in these syndromes have been identified, a few studies have attempted to estimate the spontaneous mutation rate (de novo mutation rate) in these populations. Interestingly, PJS, PTEN hamartoma syndromes, and LFS are all thought to have high rates of spontaneous mutations, in the 10% to 30% range,[640-643] while estimates of de novo mutations in the BRCA genes are thought to be low, primarily on the basis of the few case reports published.[644-652] Additionally, there has been only one case series of breast cancer patients who were tested for BRCA mutations in which a de novo mutation was identified. Specifically, in this study of 193 patients with sporadic breast cancer, 17 mutations were detected, one of which was confirmed to be a de novo mutation.[644] As such, the de novo mutation rate appears to be low and fall into the 5% or less range based on the limited studies performed.[644-652] Similarly, estimates of de novo mutations in the MMR genes associated with LS are thought to be low, in the 0.9% to 5% range.[653-655] However, it is important to note that these estimates of spontaneous mutation rates in the BRCA genes and LS genes seem to overlap with the estimates of nonpaternity rates in various populations (0.6%–3.3%),[656-658] making the de novo mutation rate for these genes relatively low.

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Low- and Moderate-Penetrance Genes Associated With Breast and/or Ovarian Cancer



Background

Mutations in BRCA1, BRCA2, and the genes involved in other rare syndromes discussed in the High-Penetrance Breast and/or Ovarian Cancer Susceptibility Genes section of this summary account for less than 25% of the familial risk of breast cancer.[1] Despite intensive genetic linkage studies, there do not appear to be other BRCA1/BRCA2-like high-penetrance genes that account for a significant fraction of the remaining multiple-case familial clusters.[2] These observations suggest that the remaining breast cancer susceptibility is polygenic in nature, meaning that a relatively large number of low-penetrance genes are involved.[3] On its own, each low-penetrance locus would be expected to have a relatively small effect on breast cancer risk and would not produce dramatic familial aggregation or influence patient management. However, in combination with other genetic loci and/or environmental factors, particularly given how common these can be, variants of this kind might significantly alter breast cancer risk. These types of genetic variations are sometimes referred to as “polymorphisms,” meaning that the gene or locus occurs in several “forms” within the population (and more formally defined as polymorphic when a specific variation in a given locus occurs in more than 1% of the population). Most loci that are polymorphic have no influence on disease risk or human traits (benign polymorphisms), while those that are associated with a difference in risk of disease or a human trait (however subtle) are sometimes termed “disease-associated polymorphisms” or “functionally relevant polymorphisms.” This polygenic model of susceptibility is consistent with the observed patterns of familial aggregation of breast cancer.[4] Although the clinical significance and causality of associations with breast cancer are often difficult to evaluate and establish, genetic polymorphisms may account for why some individuals are more sensitive than others to environmental carcinogens.[5]

Polymorphisms underlying polygenic susceptibility to breast cancer are considered low penetrance, a term often applied to sequence variants associated with a minimal to moderate risk. This is in contrast to “high-penetrance” variants or alleles that are typically associated with more severe phenotypes, for example those BRCA1/BRCA2 mutations leading to an autosomal dominant inheritance patterns in a family. The definition of a “moderate” risk of cancer is arbitrary, but it is usually considered to be in the range of a relative risk (RR) of 1.5 to 2.0. Because these types of sequence variants (also called low-penetrance genes, alleles, mutations, and polymorphisms) are relatively common in the general population, their contribution to cancer risk overall is estimated to be much greater than the attributable risk in the population from mutations in BRCA1 and BRCA2. For example, it is estimated by segregation analysis that half of all breast cancer occurs in 12% of the population that is deemed most susceptible.[3] There are no known low-penetrance variants in BRCA1/BRCA2. The N372H variation in BRCA2, initially thought to be a low-penetrance allele, was not verified in a large combined analysis.[6]

Two strategies have been taken to identify low-penetrance polymorphisms leading to breast cancer susceptibility: candidate gene and genome-wide searches. Both involve the epidemiologic case-control study design. The candidate gene approach involves selecting genes based on their known or presumed biological function, relevance to carcinogenesis or organ physiology, and searching for or testing known genetic variants for an association with cancer risk. This strategy relies on imperfect and incomplete biological knowledge, and, despite some confirmed associations (described below), has been relatively disappointing.[6,7] The candidate gene approach has largely been replaced by the genome-wide association studies (GWAS) in which a very large number of single nucleotide polymorphisms (SNPs) (potentially 1 million or more) are chosen within the genome and tested, mostly without regard to their possible biological function, but instead to capture all genetic variation throughout the genome more uniformly.

Breast Cancer Susceptibility Genes Identified Through Candidate Gene Approaches

There is a very large literature of genetic epidemiology studies describing associations between various loci and breast cancer risk. Many of these studies suffer from significant design limitations. Perhaps as a consequence, most reported associations do not replicate in follow-up studies. This section is not a comprehensive review of all reported associations. This section describes associations that are believed by the editors to be clinically valid, in that they have been described in several studies or are supported by robust meta-analyses. The clinical utility of these observations remains unclear, however, as the risks associated with these variations usually fall below a threshold that would justify a clinical response.

CHEK2

CHEK2 (OMIM) is a gene involved in the DNA damage repair response pathway. Based on numerous studies, a polymorphism, 1100delC, appears to be a rare, moderate-penetrance cancer susceptibility allele.[8-13] One study identified the mutation in 1.2% of the European controls, 4.2% of the European BRCA1/BRCA2-negative familial breast cancer cases, and 1.4% of unselected female breast cancer cases.[8] In a group of 1,479 Dutch women younger than 50 years with invasive breast cancer, 3.7% were found to have the CHEK2 1100delC mutation.[14] In additional European and U.S. (where the mutation appears to be slightly less common) studies, including a large prospective study,[15] the frequency of CHEK2 mutations detected in familial breast or ovarian cancer cases has ranged from 0% [16] to 11%; overall, these studies have found an approximately 1.5-fold to 3-fold increased risk of female breast cancer.[15,17-20] A multicenter combined analysis and reanalysis of nearly 20,000 subjects from ten case-control studies, however, has verified a significant 2.3-fold excess of breast cancer among mutation carriers.[21] A subsequent meta-analysis based on 29,154 cases and 37,064 controls from 25 case-control studies found a significant association between CHEK2 1100delC heterozygotes and breast cancer risk (odds ratio [OR], 2.75; 95% confidence interval [CI], 2.25–3.36). The ORs and CIs in unselected, familial, and early-onset breast cancer subgroups were 2.33 (1.79–3.05), 3.72 (2.61–5.31), and 2.78 (2.28–3.39), respectively. However, study limitations included pooling of populations without subgroup analysis, using a mix of population-based and hospital-based controls, and basing results on unadjusted estimates (as cases and controls were matched on only a few common factors); therefore, results should be interpreted in the context of these limitations.[22]

Two studies have suggested that the risk associated with a CHEK2 1100delC mutation was stronger in the families of probands ascertained because of bilateral breast cancer.[23,24] Furthermore, a meta-analysis of 1100delC mutation carriers estimated the risk of breast cancer to be 42% by age 70 years in women with a family history of breast cancer.[25] Similarly, a Polish study reported that CHEK2 truncating mutations confer breast cancer risks based on a family history of breast cancer as follows: no family history: 20%; one second-degree relative: 28%; one first-degree relative: 34%; and both first- and second-degree relatives: 44%.[26] Moreover, a Dutch study suggested that female homozygotes for the CHEK2 1100delC mutation have a greater-than-twofold increased breast cancer risk compared with heterozygotes.[27] Although there have been conflicting reports regarding cancers other than breast cancer associated with CHEK2 mutations, this may be dependent on mutation type (i.e., missense vs. truncating) or population studied and is not currently of clinical utility.[13,18,28-33] The contribution of CHEK2 mutations to breast cancer may depend on the population studied, with a potentially higher mutation prevalence in Poland.[34] CHEK2 mutation carriers in Poland may be more susceptible to ER-positive breast cancer.[35]

Currently, the clinical applicability of CHEK mutations remains uncertain because of low mutation prevalence and lack of guidelines for clinical management.[36]

(Refer to the CHEK2 section in the PDQ summary on Genetics of Colorectal Cancer for more information.)

ATM

Ataxia telangiectasia (AT) (OMIM) is an autosomal recessive disorder characterized by neurologic deterioration, telangiectasias, immunodeficiency states, and hypersensitivity to ionizing radiation. It is estimated that 1% of the general population may be heterozygote carriers of ATM mutations (OMIM).[37] More than 300 mutations in the gene have been identified, most of which are truncating mutations.[38] ATM proteins have been shown to play a role in cell cycle control.[39-41] In vitro, AT-deficient cells are sensitive to ionizing radiation and radiomimetic drugs, and lack cell cycle regulatory properties after exposure to radiation.[42]

Initial studies searching for an excess of ATM mutations among breast cancer patients provided conflicting results, perhaps due to study design and mutation testing strategies.[43-53] However, two large epidemiologic studies have demonstrated a statistically increased risk of breast cancer among female heterozygote carriers, with an estimated RR of approximately 2.0.[53,54] Despite this convincing epidemiologic association, the clinical application of testing for ATM mutations is unclear due to the wide mutational spectrum and the logistics of testing. Because the presence of a mutation could pose a risk in screening-related radiation exposure, further investigation is needed.

BRIP1

BRIP1 (also known as BACH1) encodes a helicase that interacts with the BRCA1 C-terminal (BRCT) domain. This gene also has a role in BRCA1-dependent DNA repair and cell cycle checkpoint function. Biallelic mutations in BRIP1 are a cause of Fanconi anemia,[55-57] much like such mutations in BRCA2. Inactivating mutations of BRIP1 are associated with an increased risk of breast cancer. In one study, more than 3,000 individuals from BRCA1/BRCA2 mutation negative families were examined for BRIP1 mutations. Mutations were identified in 9 of 1,212 individuals with breast cancer but in only 2 of 2,081 controls (P = .003). The RR of breast cancer was estimated to be 2.0 (95% CI, 1.2–3.2; P = .012). Of note, in families with BRIP1 mutations and multiple cases of breast cancer, there was incomplete segregation of the mutation with breast cancer, consistent with a low penetrance allele and similar to that seen with CHEK2.[58]

PALB2

PALB2 (partner and localizer of BRCA2) interacts with the BRCA2 protein and plays a role in homologous recombination and double-stranded DNA repair. Similar to BRIP1 and BRCA2, biallelic mutations in PALB2 have also been shown to cause Fanconi anemia.[59] PALB2 mutations have been screened for in multiple small studies of familial and early-onset breast cancer in multiple populations.[60-72] Mutation prevalence has ranged from 0.4% to 3.4%. Similar to BRIP1 and CHEK2, there was incomplete segregation of PALB2 mutations in families with hereditary breast cancer.[61] Among 559 cases with contralateral breast cancer and 565 matched controls with unilateral breast cancer, pathogenic (truncating) PALB2 mutations were identified in 0.9% of cases and in none of the controls (RR, 5.3; 95% CI, 1.8–13.2).[72] A Finnish PALB2 founder mutation (c.1592delT) has been reported to confer a 40% risk of breast cancer to age 70 years [62] and is associated with a high incidence (54%) of triple-negative disease and lower survival.[63] Mutations have been observed in early-onset and familial breast cancer in many populations.[64,65]

Male breast cancer has been observed in PALB2 mutation–positive breast cancer families.[60,66] In a study of 115 male breast cancer cases in which 18 men had BRCA2 mutations, an additional two men had either a pathogenic or predicted pathogenic PALB2 mutation (accounting for about 10% of germline mutations in the study and 1%–2% of the total sample).[60] After the identification of PALB2 mutations in pancreatic tumors and the detection of germline mutations in 3% of 96 familial pancreatic patients,[73] numerous studies have pointed to a role for PALB2 in pancreatic cancer. A sixfold increase in pancreatic cancer was observed in the relatives of 33 BRCA1/2-negative, PALB2 mutation–positive breast cancer probands.[66] PALB2 mutations were detected in 3.7% of 81 familial pancreatic cancer families [74] and in 2.1% of 94 BRCA1/2 mutation–negative breast cancer patients who had either a personal or family history of pancreatic cancer.[75] Two relatively small studies, one of 77 BRCA1/2 mutation–negative probands with a personal or family history of pancreatic cancer, one-half of whom were of Ashkenazi Jewish descent, and another study of 29 Italian pancreatic cancer patients with a personal or family history of breast or ovarian cancer, failed to detect any PALB2 mutations.[76,77]

The observed prevalence of PALB2 mutations in familial breast cancer varied depending on ascertainment relative to personal and family history of pancreatic and ovarian cancers, but in all studies, the observed mutation rate was less than 4%. The RR of breast cancer appears moderate, and the risk of other cancers (e.g., pancreatic) is poorly defined; therefore, the clinical utility of testing is not clear. There is insufficient evidence to support routine screening of PALB2 when tests of the more common genes, namely BRCA1/2, are negative.

CASP8 and TGFB1

The Breast Cancer Association Consortium (BCAC), an international group of investigators, investigated SNPs identified in previous studies as possibly associated with excess breast cancer risk in 15,000 to 20,000 cases and 15,000 to 20,000 controls. Two SNPs, CASP8 D302H and TGFB1 L10P, were associated with invasive breast cancer with RRs of 0.88 (95% CI, 0.84–0.92) and 1.08 (95% CI, 1.04–1.11), respectively.[78]

RAD51

RAD51 and the family of RAD51-related genes, also known as RAD51 paralogs, are thought to encode proteins that are involved in DNA damage repair through homologous recombination and interaction with numerous other DNA repair proteins, including BRCA1 and BRCA2. RAD51 protein plays a central role in single-strand annealing in the DNA damage response. RAD51 recruitment to break sites and recombinational DNA repair depend on the RAD51 paralogs, although their precise cellular functions are poorly characterized.[79] Mutations in these genes are thought to result in loss of RAD51 focus formation in response to DNA damage.[80]

One of five RAD51-related genes, RAD51C has been reported to be linked to both Fanconi anemia–like disorders and familial breast and ovarian cancers. The literature, however, has produced contradictory findings. In a study of 480 German families characterized by breast and ovarian cancers who were negative for BRCA1 and BRCA2 mutations, six monoallelic mutations in RAD51C were found (frequency of 1.3%).[81] No mutations were found in breast cancer–only families or in healthy controls. Another study screened 286 BRCA1/2-negative patients with breast cancer and/or ovarian cancer and found one likely deleterious mutation in RAD51C-G153D.[82] RAD51C mutations have also been reported in Australian, Finnish, and Spanish non-BRCA1/2 ovarian cancer–only and breast/ovarian cancer families, and in unselected ovarian cancer cases.[83-87] In a sample of 206 high-risk Jewish women (including 79 of Ashkenazi origin) previously tested for the common Jewish mutations, two previously described and possibly pathogenic missense mutations were detected.[88] Four additional studies were unable to confirm an association between the RAD51C gene and hereditary breast cancer or ovarian cancer.[70,89-91]

In addition to RAD51C mutation carriers, there are other RAD51 paralogs, including RAD51D and RAD51L1, that may be associated with breast and/or ovarian cancer risk,[92-96] although the clinical significance of these findings is unknown.

In addition to germline mutations, different polymorphisms of RAD51 have been hypothesized to have reduced capacity to repair DNA defects, resulting in increased susceptibility to familial breast cancer. The Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) pooled data from 8,512 BRCA1 and BRCA2 mutation carriers and found evidence of an increased risk of breast cancer among women who were BRCA2 carriers and who were homozygous for CC at the RAD51 135G→C SNP (hazard ratio, 1.17; 95% CI, 0.91–1.51).[97]

Several meta-analyses have investigated the association between the RAD51 135G→C polymorphism and breast cancer risk. There is significant overlap in the studies reported in these meta-analyses, significant variability in the characteristics of the populations included, and significant methodologic limitations to their findings.[98-101] A meta-analysis of nine epidemiologic studies involving 13,241 cases and 13,203 controls of unknown BRCA1/2 status found that women carrying the CC genotype had an increased risk of breast cancer compared with women with the GG or GC genotype (OR, 1.35; 95% CI, 1.04–1.74). A meta-analysis of 14 case-control studies involving 12,183 cases and 10,183 controls confirmed an increased risk only for women who were known BRCA2 carriers (OR, 4.92; 95% CI, 1.10–21.83).[102] Another meta-analysis of 12 studies included only studies of known BRCA-negative cases and found no association between RAD51 135G→C and breast cancer.[103]

In summary, among this conflicting data there is substantial evidence for a weak association between germline mutations in RAD51C and breast cancer and ovarian cancer. There is also evidence of an association between polymorphisms in RAD51 135G→C among women with homozygous CC genotypes and breast cancer, particularly among BRCA2 carriers. These associations are plausible given the known role of RAD51 in the maintenance of genomic stability.

Abraxas

Mutations in the BRCA1-interacting gene Abraxas were found in three Finnish breast cancer families and no controls.[104] The significance of this finding outside of this population is not yet known.

Genome-Wide Searches

In contrast to assessing candidate genes and/or alleles, GWAS involve comparing a very large set of genetic variants spread throughout the genome. The current paradigm uses sets of as many as 5 million SNPs that are chosen to capture a large portion of common variation within the genome based on the HapMap and the 1000 Genomes Project.[105,106] By comparing allele frequencies between a large number of cases and controls, typically 1,000 or more of each, and validating promising signals in replication sets of subjects, very robust statistical signals of association have been obtained.[107-109] The strong correlation between many SNPs that are physically close to each other on the chromosome (linkage disequilibrium) allows one to “scan” the genome for susceptibility alleles even if the biologically relevant variant is not within the tested set of SNPs. Although this between-SNP correlation allows one to interrogate the majority of the genome without having to assay every SNP, when a validated association is obtained, it is not usually obvious which of the many correlated variants is causal.

Genome-wide searches are showing great promise in identifying common, low-penetrance susceptibility alleles for many complex diseases,[110] including breast cancer.[111-114] The first study involved an initial scan in familial breast cancer cases followed by replication in two large sample sets of sporadic breast cancer, the final being a collection of over 20,000 cases and 20,000 controls from the BCAC.[111] Five distinct genomic regions were identified that were within or near the FGFR2, TNRC9, MAP3K1, and LSP1 genes or at the chromosome 8q region. The 8q region and others may harbor multiple independent loci associated with risk, but these regions are included only once in Table 11. Subsequent genome-wide studies have replicated these loci and identified additional ones, as summarized in Table 11.[112,113,115,115-120] Numerous SNPs identified through large studies of sporadic breast cancer appear to be associated more strongly with estrogen receptor–positive disease;[121] however, some are associated primarily or exclusively with other subtypes, including triple-negative disease.[122,123] An online catalog of SNP-trait associations from published GWAS for use in investigating genomic characteristics of trait/disease-associated SNPs (TASs) is available.

Table 11. High-probability Breast Cancer Susceptibility Loci Identified Through Genome-Wide Association Studies
Putative Gene(s) Chromosome  SNP Study Citationa Odds Ratio (OR) (95% Confidence Interval [CI])b Comments 
Intergenic /NOTCH21p11.2rs11249433[93]1.08 (1.02–1.15) [114]Stronger in ER+, low-grade [114]; also in BRCA2 [124]
ERBB2 2q34rs13393577[125]1.53 (1.37–1.70) [125]Identified in Korean subjects [125]
Intergenic2q35rs13387042[112]1.21 (1.14–1.29) [114]Stronger in bilateral and lobular [121]; also in BRCA1 and BRCA2 [126]
SLC4A7, NEK103p24rs4973768[120]1.16 (1.10–1.24) [114]Also in BRCA2 [126]
MRPS30 5p12rs10941679[119]1.11c (1.04–1.19) [114]Strongest in PR+, low-grade [127]; also in BRCA2 [126]
TERT-/CLPTM15p15rs10069690[122]1.25 (1.16–1.34) [122]Strongest in triple-negative [122]
MAP3K1 5q11.2rs889312[111]1.22 (1.14–1.30) [114]Stronger in ER+ [114]; also in BRCA2 [126]
RNF146 6q22rs2180341[115]1.24 (1.13–1.36) [128]Stronger in Ashkenazi Jews [128]
ESR1 6q25.1rs2046210[116]1.15c (1.08–1.22) [114]Also in BRCA1 [124]
TAB2 6q25.1rs9485372[129]0.90 (0.87–0.92) [129]Identified in Chinese subjects [129]
Intergenic7q32.3rs2048672[130]1.11 (1.05–1.17) [130]Identified in East Asian subjects [130]
Intergenic/MYC8q24.21rs13281615[111]1.14 (1.07–1.21) [114]Stronger in ER+ [114]
CDKN2A, CDKN2B 9p21rs1011970[114]1.09 (1.04–1.14) [114]Stronger in ER+ [114]; also in BRCA2 [131]
Intergenic9q31.2rs865686[132]0.89(0.85–0.92) [132]Also in BRCA2 [131]
ANKRD16, FBXO18 10p15.1rs2380205[114]0.94 (0.91–0.98) [114]
ZNF365 10q21.2rs10995190[114]0.86 (0.82–0.91) [114]Stronger in ER+ in general population [114]; also in BRCA2 [133]
ZMIZ1 10q22.3rs704010[114]1.07 (1.03–1.11) [114]
FGFR2 10q26.13rs2981582[111]1.43 (1.35–1.53) [114]Strongest for ER+, low-grade [121]; also in BRCA2 [126]
LSP1 11p15.5rs3817198[111]1.12 (1.05–1.19) [114]Also in BRCA2 [126]
Intergenic11q13rs614367[114]1.15 (1.10–1.20) [114]Restricted to ER+ tumors; strongest for ER+/PR+[114]
BARX211q24.3rs7107217[129]1.08 (1.05–1.11) [129]Identified in Chinese subjects [129]
PTHLH 12p11rs10771399[134]0.85 (0.83–0.88) [134]Also in BRCA1 [131]
Intergenic12q24rs1292011[134]0.92 (0.91–0.94) [134]Restricted to ER+ [134]; also in BRCA2 [131]
RAD51B 14q24.1rs999737[93]0.89 (0.83–0.95) [114]Associated with all subtypes, including triple-negative [94]; also in BRCA2 [131]
TOX3 16q12.1rs3803662[111]1.30 (1.22–1.39) [114]Stronger in ER+ [121]; also in BRCA1 and BRCA2 [126]
COX11 17q23.2rs6504950[120]0.92c (0.86–0.99) [114]
BABAM1 19p13.1rs8170[123]1.26 (1.17–1.35) [135]Restricted to triple-negative in general population [123]; also in BRCA1 [135]
NRIP1 21q21rs2823093[134]0.94 (0.92–0.96) [134]Restricted to ER+ [134]

ER- = estrogen receptor–negative; ER+ = estrogen receptor–positive; PR- = progesterone receptor–negative; PR+ = progesterone receptor–positive; SNP = single nucleotide polymorphism; triple-negative = ER-/PR-/HER2/neu-.
aInitial study that demonstrated genome-wide significance for each locus.
bAll associations observed in the general population, unless otherwise indicated; when relevant, if association was also observed in BRCA1 or BRCA2 mutation carriers, it is indicated.
cOR for best tag SNP was used [114] as a surrogate for published SNP.

Table 12. High-probability Ovarian Cancer Susceptibility Loci Identified Through Genome-Wide Association Studies
Putative Gene(s) Chromosome SNP Study Citation Odds Ratio (95% Confidence Interval) Comment 
SNP = single nucleotide polymorphism.
HOXD1 2q31.1rs2072590[136]1.16 (1.12–1.21)Stronger in serous cancers
TIPARP 3q25.31rs2665390[136]1.19 (1.11–1.27)
Intergenic/MYC, THEM758q24.21rs10088218[136]0.84 (0.80–0.89)
BNC2 9p22.2rs3814113[137]0.82 (0.79–0.86)Stronger in serous cancers; also in BRCA1 and BRCA2 [138]
SKAP1 17q21.32rs9303542[136]1.11 (1.06–1.16)
BABAM1 19p13.11rs8170[139]1.18 (1.12–1.25)Serous cancers only
ANKLE1 19p13.11rs2363956[139]1.16 (1.11–1.21)

Although the statistical evidence for an association between genetic variation at these loci and breast and ovarian cancer risk is overwhelming, the biologically relevant variants and the mechanism by which they lead to increased risk are unknown and will require further genetic and functional characterization. Additionally, these loci are associated with very modest risk (typically, OR <1.5), with more risk variants likely to be identified. No interaction between the SNPs and epidemiologic risk factors for breast cancer have been identified.[140,141] At this time, because their individual and collective influences on cancer risk have not been evaluated prospectively, they are not considered clinically relevant. Furthermore, theoretical models have suggested that common moderate-risk SNPs have limited potential to improve models for individualized risk assessment.[142-144] These models used receiver operating characteristic (ROC) curve analysis to calculate the area under the curve (AUC) as a measure of discriminatory accuracy. A more recent study used ROC curve analysis to examine the utility of SNPs in a clinical dataset of greater than 5,500 breast cancer cases and nearly 6,000 controls, using a model with traditional risk factors compared with a model using both standard risk factors and ten previously identified SNPs. The addition of genetic information modestly changed the AUC from 58% to 61.8%, a result that was not felt to be clinically significant. Despite this, 32.5% of patients were in a higher quintile of breast cancer risk when genetic information was included, and 20.4% were in a lower quintile of risk. Whether such information has clinical utility is unclear.[142,145]

More limited data are available regarding ovarian cancer risk. Three GWAS involving staged analysis of more than 10,000 cases and 13,000 controls have been carried out for ovarian cancer.[136,137,139] The seven loci that reached genome-wide significance are shown in Table 12. As in other GWAS, the ORs are modest, generally about 1.2 or weaker, but implicate a number of genes with plausible biological ties to ovarian cancer, such as BABAM1, whose protein complexes with and may regulate BRCA1, and TIRAPR, which codes for a poly (ADP-ribose) polymerase, molecules that may be important in BRCA1/BRCA2-deficient cells.

In addition to genome-wide studies interrogating common genetic variants, sequencing-based studies involving whole-genome or whole-exome sequencing [146] are also identifying genes associated with breast cancer, such as XRCC2, a rare, moderate-penetrance, breast cancer susceptibility gene.[147]

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Psychosocial Issues in Inherited Breast Cancer Syndromes



Introduction

Psychosocial research in the context of cancer genetic testing helps to define psychological outcomes, interpersonal and familial effects, and cultural and community responses. This type of research also identifies behavioral factors that encourage or impede screening and other health behaviors. It can enhance decision-making about risk-reduction interventions, evaluate psychosocial interventions to reduce distress and/or other negative sequelae related to risk notification and genetic testing, provide data to help resolve ethical concerns, and predict the interest in testing of various groups.

Research in these areas is limited by few randomized controlled trials, and many reports are based on uncontrolled studies of selected high-risk populations. Research is likely to expand considerably with access to larger populations of at-risk individuals.

There have been a number of descriptions of cancer genetics programs that provide genetic susceptibility testing.[1-9] The development of such programs was encouraged by federal funding of multidisciplinary research programs that offered intensive genetic counseling for hereditary cancer syndromes, psychological assessment and back-up, and physician involvement.[10]

Uptake of Genetic Counseling and Genetic Testing

Degree of uptake of genetic counseling and genetic testing

Comparison of uptake rates across studies is challenging because of differences in methodologies, including the sampling strategy used, the recruitment setting, and testing through a research protocol with high-risk cohorts or kindreds. In a systematic review of 40 studies conducted before 2002 that had assessed genetic testing utilization, uptake rates varied widely and ranged from 25% to 96%, with an average uptake rate of 59%.[11] Results of multivariate analysis found that BRCA1/BRCA2 genetic testing uptake was associated with having a personal or family history of breast or ovarian cancer, and with methodological features of the studies, including sampling strategies, recruitment settings, and how studies defined actual uptake versus the intention to have testing.

Other factors have been positively correlated with uptake of BRCA1/BRCA2 genetic testing, although these findings are not consistent across all studies. Psychological factors that have been positively correlated with testing uptake include greater cancer-specific distress and greater perceived risk of developing breast or ovarian cancer. Having more cancer-affected relatives also has been correlated with greater testing uptake.

Table 13 summarizes the uptake of genetic testing in clinical and research cohorts in the United States.

Table 13. Predictors Associated with Uptake of Genetic Testing (GT)
Study Citation Study Population Sample Size (N) Uptake of GT Predictors Associated With Uptake of GT Comments 
Schwartz et al. (2005) [12]Newly diagnosed and locally untreated breast cancer patients with ≥10% risk of having a BRCA1/2 mutationa231177/231 (77%) underwent GTHaving decided on definitive local treatment. Women who were undecided on a definitive local treatment were more likely to be tested.Testing was offered free of charge.
34/231 (15%) had baseline interview but declined GT
Physician recommendation for testing. Women whose physician had recommended GT were more likely to be tested.38/177 chose to proceed with treatment before receiving test results.
20/231 declined baseline interview
Kieran et al. (2007) [13]Women who received GC between 2002 and 2004a25088/250 (35%) underwent GTAbility to pay for GT (entire cost or cost not covered by insurance). Nonuptake was 5.5 times more likely in women who could not afford testing.450 women received GC for breast and ovarian cancer risk during study period. 250 women were retrospectively identified as eligible and were mailed a study questionnaire.
36/88 returned surveys
Ability to recall risk estimates that were provided post-GC. Nonuptake was 15.5 times more likely in women who could not recall their risk estimates.All women had some form of insurance.
162/250 (65%) eligible
65/162 returned surveys
Susswein et al. (2008) [14]African American women and white women with breast cancerb768529/768 (69%) underwent GTRace/ethnicity. African American women were less likely to be tested than were white women.Sample obtained from a clinical database. Testing was offered free of charge when it was not covered by insurance. This effect for time of diagnosis was significant in the African American, but not white, subgroup.
African American women: 77/132 (58%) underwent GT
Recent diagnosis. African American women who were recently diagnosed were more likely to be tested.
White women: 452/636 (71%) underwent GT
Olaya et al. (2009) [15]Patients referred for GT between 2001 and 2008b213111/213 (52%) underwent GTPersonal history of breast cancer. Having a personal history was associated with 3 times greater odds of being tested.Insurance coverage for testing was available for 91.1% (175/213) of patients. Of those who had coverage for GT, 51.4% underwent testing and 48.6% did not. Of those without coverage, 41.2% had GT and 58.9% did not.
102/213 (48%) declined GTHigher level of education. Those with a high school education or less had one-third the odds of being tested, compared with those with at least some college.
Levy et al. (2010) [16]Women aged 20–40 y with newly diagnosed early-onset breast cancer.b1,474446/1,474 (30%) underwent GTRace/ethnicity. Women of Jewish ethnicity were 3 times more likely to be tested than were non-Jewish white women. African American and Hispanic women were significantly less likely to receive testing than were non-Jewish white women.Sample obtained from a national database of commercially insured individuals.
Jewish women: 18/32 (56%) underwent GTHome location. Women living in the south were more likely to be tested than were women living in the northeast.
African American women: 10/82 (12%) underwent GTInsurance type. Women with point-of-service plans were more likely to be tested than were women with HMO plans.
Recent diagnosis. Women diagnosed in 2007 were 3.8 times more likely to be tested than were women diagnosed in 2004.

GC = genetic counseling; HMO = health maintenance organization.
aSelf-report as data source.
bMedical records as data source.

Several studies conducted in non-U.S. settings have examined the uptake of genetic testing.[17-21] In studies examining the uptake of testing among at-risk relatives of BRCA1/BRCA2 mutation carriers, uptake rates have averaged below 50% (range, 36%–48%), with higher uptake reported among female relatives than in male relatives. Other factors associated with higher uptake of testing were not consistently reported among studies but have most commonly included being a parent and wanting to learn information about a child’s risk.

Factors influencing uptake of genetic counseling and genetic testing

In reviews that have examined the cumulative evidence concerning the predictors of uptake of BRCA1/BRCA2 genetic testing, important predictors of testing uptake include older age, Ashkenazi Jewish (AJ) heritage, unmarried status, a personal history of breast cancer, and a family history of breast cancer. Studies recruiting participants in hospital settings had significantly higher recruitment rates than did studies recruiting participants in community settings. Studies that required an immediate decision to test, rather than allowing delayed decision making, tended to report higher uptake rates.[11] However, there is evidence that women diagnosed with breast cancer are equally satisfied with genetic counseling (including information received and strength and timing of physician recommendations for counseling), whether they received genetic counseling before or after their definitive surgery for breast cancer.[22] Another review [23] found that uptake of genetic testing for BRCA1/2 mutations was related to psychological factors (e.g., anxiety about breast cancer and perceived risk of breast cancer) and demographic and medical factors (e.g., history of breast cancer or ovarian cancer, presence of children, and higher number of affected first-degree relatives). Family members with a known BRCA1/2 mutation were more likely to pursue testing; those with more extensive knowledge of BRCA1/2 testing, heightened risk perceptions, beliefs that mammography would promote health benefit, and high intentions to undergo testing were more likely to follow through with testing.[24]

In a review of racial/ethnic differences that affect uptake of BRCA1/2 testing, intention to undergo genetic testing in African American women was related to having at least one first-degree relative with breast cancer or ovarian cancer, higher perceived risk of being a carrier, and less anticipatory guilt about the possibility of being a gene carrier.[25]

Reasons cited for following through with testing included a desire to learn about a child's risk, to feel relief from uncertainty, to inform screening or prophylactic surgery decisions, and to inform important life decisions such as marriage and childbearing.[24,26] Among African American women, the most important reason for testing included motivation to help other relatives decide on genetic testing.[25]

Physician recommendation may be another motivator for testing. In a retrospective study of 335 women considering genetic testing, 77% reported that they wanted the opinion of a genetics physician about whether they should be tested, and 49% wanted the opinion of their primary care provider.[27] However, there is some evidence of referral bias favoring those with a maternal family history of breast cancer or ovarian cancer. In a Canadian retrospective review of 315 patients, those with a maternal family history of breast cancer or ovarian cancer were 4.9 times (95% confidence interval, 3.6–6.7) more likely to be referred for a cancer genetics consultation by their physician than were those with a paternal family history (P < .001).[28] Studies have found that physicians may not adequately assess paternal family history [29] or may underestimate the significance of a paternal family history for genetic risk.[29-31]

Insurance coverage

In May 2011, a case study examined coverage for BRCA1/2 testing using National Comprehensive Cancer Network (NCCN) clinical guidelines. The online databases included data from large private insurers (eight payers, including Aetna, Cigna, Humana, and United HealthCare) and public insurance policies, including Medicare (Washington state) and four Medicaid policies (Arizona, California, Illinois, and New York). Overall, more consistent policies were available for private than for public payers, indicating better communication of eligibility criteria and transparency of coverage. However, across all types of coverage, including private coverage, the criteria were inconsistent for coverage of genetic counseling services. Of note, the Medicare policies only covered individuals with a history of breast cancer, not those with strong family histories, as outlined by NCCN.[32]

Conducted in 2008, another study examined coverage policies from all third-party payers in Illinois and documented relative consistency in coverage for genetic testing for breast/ovarian cancer and colorectal cancer susceptibility, but much less consistent approaches to coverage for genetic counseling services; for example, several policies would not cover genetic counseling services unless the patient ultimately decided against genetic testing.[33] One example of success in changing coverage plans was initiated by the Michigan Department of Community Health, which used a cooperative agreement with the Centers for Disease Control and Prevention to raise awareness and provide guidance for an increase in written policies regarding BRCA1/2 testing, increasing utilization from 4 to 11 health plans.[34] As of August 2011, 11 of 24 Michigan health plans had written BRCA1/2 genetic testing policies aligned with U.S. Preventive Services Task Force guidelines. There is evidence that concerns about genetic discrimination are decreasing. A 2007 survey of genetic counselors reported that most (94%) felt the risk of insurance discrimination resulting from genetic testing was low, and that they were confident in U.S. laws to protect against genetic discrimination.[35]

Uptake of genetic counseling and genetic testing in diverse populations

Degree of uptake of genetic counseling and genetic testing in diverse populations

There are limited data on uptake of genetic counseling and testing among nonwhite populations, and further research will be needed to define factors influencing uptake in these populations.[36] The uptake of BRCA testing appears to vary across some racial/ethnic groups. A few studies have compared uptake rates between African American and white women.[14,37] In a case-control study of women who had been seen in a university-based primary care system, African American women with family histories of breast cancer or ovarian cancer were less likely to undergo BRCA1/2 testing than were white women who had similar histories.[37] In another study among breast cancer patients who were counseled about BRCA1/2 risk in a clinical setting, lower uptake was reported among African American women than among white women.[14]

Notably, the racial differences observed in these studies do not appear to be explained by factors related to cost, access to care, risk factors for carrying a BRCA1 or BRCA2 mutation, or differences in psychosocial factors, including risk perceptions, worry, or attitudes toward testing.

Factors influencing uptake of genetic counseling and genetic testing in diverse populations

Several studies have examined uptake or “acceptance” of BRCA testing among African Americans enrolled in genetic research programs. Among study enrollees from an African American kindred in Utah, 83% underwent BRCA1 testing.[38] Age, perceived risk of being a carrier, and more extensive cancer knowledge predicted testing acceptance. Another study that recruited African American women through physician and community referrals reported a BRCA1/2 testing acceptance rate of 22%.[39] Predictors of test acceptance included having a higher probability of having a mutation, being married, and being less certain about one’s cancer risk. Finally, a third study that recruited at-risk African American women from an urban cancer screening clinic found that acceptors of BRCA testing were more knowledgeable about breast cancer genetics and perceived fewer barriers to testing, including negative emotional reactions, stigmatization concerns, and family-related guilt.[40] While these are independent predictors of genetic testing uptake, they do not explain the disparities in testing uptake across different ethnic groups. What may explain these differences are several attitudes and beliefs held about testing by individuals from diverse populations.

Recent work examining attitudes toward breast cancer genetic testing in African American and Latino populations indicates limited knowledge and awareness about testing but a generally receptive view once they are informed; in comparison with whites, African American and Latino populations have relatively more concerns about testing.

For example, in a qualitative focus group study with 51 Latino individuals unselected for risk status, important findings included the fact that participants were highly interested in genetic testing for inherited cancer susceptibility, despite very limited knowledge about genetics. One important barrier involved secrecy or embarrassment about family discussions of cancer and genetics, which could be addressed in intervention strategies.[41] Similarly, a telephone survey of 314 patients, 50% of whom were African American, from an inner-city network of Pittsburgh, Pennsylvania, health centers found that most participants (57%) (both African Americans and whites) felt that genetic testing to evaluate disease risk was a good idea; however, more African Americans than whites thought that genetic testing would lead to racial discrimination (37% vs. 22%, respectively) and that genetics research was unethical and tampered with nature (20% vs. 11%, respectively).[42] Finally, in a study of 222 women in Savannah, Georgia, where most had neither a personal history (70%) nor a family history (60%) of breast cancer, African American women (who comprised 26% of the sample) were less likely to be aware of breast cancer genes and genetic testing. Awareness was also related to higher income, higher education level, and having a family breast cancer history. However, 74% of the entire sample expressed willingness to be tested for breast cancer susceptibility.[43]

In a sample of 146 African American women meeting criteria for BRCA1/2 mutation testing, women born outside the United States reported higher levels of anticipated negative emotional reactions (e.g., fear, hopelessness, and lack of confidence that they could emotionally handle testing). Higher levels of breast cancer–specific distress were associated with anticipated negative emotional reactions, confidentiality concerns, and anticipated guilt regarding the family impact of breast cancer genetic testing.[44] A future orientation (e.g., "I often think about how my actions today will affect my health when I am older") was associated with overall perceived benefits of breast cancer genetic testing in this population (n = 140); however, future orientation was also found to be positively associated with family-related cons of testing, including family guilt and worry regarding the impact of testing on the family.[45]

Factors associated with declining genetic counseling and testing

There is evidence that primary reasons for declining testing involves being childless, which reduces any family motivations for testing; and concerns about the negative ramifications of testing, including difficulty retaining insurance or concerns about personal health.

Limited data are available about the characteristics of at-risk individuals who decline to be tested or have never been tested. It is difficult to access samples of test decliners because they may be reluctant to participate in research studies. Studies of genetic testing uptake are difficult to compare because people may decline at different points and with different amounts of pretest education and counseling. One study found that 43% of affected and unaffected individuals from hereditary breast/ovarian cancer families who completed a baseline interview regarding testing declined to be tested. Most individuals who declined testing chose not to participate in educational sessions. Decliners were more likely to be male and be unmarried, and have fewer relatives with breast cancer. Decliners who had high levels of cancer-related stress had higher levels of depression. Decliners lost to follow-up were significantly more likely to be affected with cancer.[46]

Another study looked at a small number (n = 13) of women decliners who carried a 25% to 50% probability of harboring a BRCA mutation; these nontested women were more likely to be childless and to have higher levels of education. This study showed that most women decided not to undergo the test after serious deliberation about the risks and benefits. Satisfaction with frequent surveillance was given as one reason for nontesting by most of these women.[47] Other reasons for declining included having no children and becoming acquainted with breast/ovarian cancer in the family relatively early in their lives.[46,47]

A third study evaluated characteristics of 34 individuals who declined BRCA1/2 testing in a large multicenter study in the United Kingdom. Decliners were younger than a national sample of test acceptors, and female decliners had lower mean scores on a measure of cancer worry. Although 78% of test decliners/deferrers felt that their health was at risk, they reported that learning about their BRCA1/2 mutation status would cause them to worry about the following:

  • Their children's health (76%).
  • Their life insurance (60%).
  • Their own health (56%).
  • Loss of their job (5%).
  • Receiving less screening if they did not carry a BRCA1/2 mutation (62%).

Apprehension about the impact of the test result was a more important factor in the decision to decline testing than were concrete burdens such as time required to travel to a genetics clinic and time spent away from work, family, and social obligations.[48] In 15% (n = 31) of individuals from 13 hereditary breast and ovarian cancer families who underwent genetic education and counseling and declined testing for a documented mutation in the family, positive changes in family relationships were reported—specifically, greater expressiveness and cohesion—compared with those who pursued testing.[49]

Genetic counseling and testing in children

Testing for BRCA1/2 mutations has been almost universally limited to adults older than 18 years. The risks of testing children for adult-onset disorders such as breast and ovarian cancers, as inferred from developmental data on children’s medical understanding and ability to provide informed consent, have been outlined in several reports.[50-53]

Studies suggest that persons who have undergone BRCA1/2 genetic testing or who are adult offspring of persons who have had testing are generally not in favor of testing minors.[54,55] Although the data are limited, research suggests that males, mutation noncarriers, and those whose mothers did not have personal histories of breast cancer may be more likely to favor genetic testing in minors in general.[54] Of those who had minor children at the time the study was conducted, only 17% stated a preference for having their own children tested. Concerns regarding testing of minors included psychological risks and insufficient maturity. Potential benefits included the ability to influence health behaviors.[55]

No data exist on the testing of children for BRCA1/2 mutations, although some researchers believe it is necessary to test the validity of assumptions underlying the general prohibition of testing children for genetic mutations associated with breast and ovarian cancers and other adult-onset diseases.[56-58] In one study, 20 children (aged 11–17 years) of a selected group of mothers undergoing genetic testing (80% of whom previously had breast cancer and all of whom had discussed BRCA1/2 testing with their children) completed self-report questionnaires on their health beliefs and attitudes toward cancer, feelings related to cancer, and behavioral problems.[59] Ninety percent of children thought they would want cancer risk information as adults; half worried about themselves or a family member developing cancer. There was no evidence of emotional distress or behavioral problems.

What People Bring to Genetic Testing: Impact of Risk Perception, Health Beliefs, and Personality Characteristics

The emerging literature in this area suggests that risk perceptions, health beliefs, psychological status, and personality characteristics are important factors in decision-making about breast/ovarian cancer genetic testing. Many women presenting at academic centers for BRCA1/BRCA2 testing arrive with a strong belief that they have a mutation, having decided they want genetic testing, but possessing little information about the risks or limitations of testing.[60] Most mean scores of psychological functioning at baseline for subjects in genetic counseling studies were within normal limits.[61] Nonetheless, a subset of subjects in many genetic counseling studies present with elevated anxiety, depression, or cancer worry.[62,63] Identification of these individuals is essential to prevent adverse outcomes. In a study of 205 women pursuing genetic counseling, interactions among cancer worry, breast cancer risk perception, and perceived severity of having a breast cancer gene mutation were found such that those with high worry, high breast cancer risk perception, and low perceived severity were twice as likely to follow through with BRCA1/BRCA2 testing than others.[64]

A general tendency to overestimate inherited risk of breast and ovarian cancer has been noted in at-risk populations,[65-67] in cancer patients,[66,68,69] in spouses of breast and ovarian cancer patients,[70] and among women in the general population.[71-73] but underestimation of breast cancer risk in higher-risk and average-risk women also has been reported.[74] This overestimation may encourage a belief that BRCA1/BRCA2 genetic testing will be more informative than it is currently thought to be. Some evidence exists that even counseling does not dissuade women at low to moderate risk from the belief that BRCA1 testing could be valuable.[36] Overestimation of both breast and ovarian cancer risk has been associated with nonadherence to physician-recommended screening practices.[75,76] A meta-analysis of 12 studies of outcomes of genetic counseling for breast/ovarian cancer showed that counseling improved the accuracy of risk perception.[77]

Women appear to be the prime communicators within families about the family history of breast cancer.[78] Higher numbers of maternal versus paternal transmission cases are reported,[79] likely due to family communication patterns, to the misconception that breast cancer risk can only be transmitted through the mother, and to the greater difficulty in recognizing paternal family histories because of the need to identify more distant relatives with cancer. In an analysis of 2,505 women participating in the Family Healthware Impact Trial,[80] not only was evidence of underreporting of paternal family history identified, but also women reported a lower level of perceived breast cancer risk with a paternal versus maternal breast cancer family history.[81] Physicians and counselors taking a family history are encouraged to elicit paternal and maternal family histories of breast, ovarian, or other associated cancers.[78]

The accuracy of reported family history of breast or ovarian cancer varies; some studies found levels of accuracy above 90%,[82,83] with others finding more errors in the reporting of cancer in second-degree or more distant relatives [84] or in age of onset of cancer.[85] Less accuracy has been found in the reporting of cancers other than breast cancer. Ovarian cancer history was reported with 60% accuracy in one study compared with 83% accuracy in breast cancer history.[86] Providers should be aware that there are a few published cases of Munchausen syndrome in reporting of false family breast cancer history.[87] Much more common is erroneous reporting of family cancer history due to unintentional errors or gaps in knowledge, related in some cases to the early death of potential maternal informants about cancer family history.[78] (Refer to the Taking a Family History section of the Cancer Genetics Risk Assessment and Counseling summary for more information.)

Targeted written,[88,89] video, CD-ROM, interactive computer program,[90-94] and culturally targeted educational materials [95-97] may be effective and efficient methods of increasing knowledge about the pros and cons of genetic testing. Such supplemental materials may allow more efficient use of the time allotted for pretest education and counseling by genetics and primary care providers and may discourage individuals without appropriate indication of risk from seeking genetic testing.[88]

Genetic Counseling for Hereditary Predisposition to Breast Cancer

Counseling for breast cancer risk typically involves individuals with family histories that are potentially attributable to BRCA1 or BRCA2. It also, however, may include individuals with family histories of Li-Fraumeni syndrome, ataxia-telangiectasia, Cowden syndrome, or Peutz-Jeghers syndrome.[98] (Refer to the High-Penetrance Breast and/or Ovarian Cancer Susceptibility Genes section of this summary for more information.)

Management strategies for carriers may involve decisions about the nature, frequency, and timing of screening and surveillance procedures, chemoprevention, risk-reducing surgery, and use of hormone replacement therapy (HRT). The utilization of breast conservation and radiation as cancer therapy for women who are carriers may be influenced by knowledge of mutation status. (Refer to the Clinical management of BRCA mutation carriers section of this summary for more information.)

Counseling also includes consideration of related psychosocial concerns and discussion of planned family communication and the responsibility to warn other family members about the possibility of having an increased risk of breast, ovarian, and other cancers. Data are emerging that individual responses to being tested as adults are influenced by the results status of other family members.[99,100] Management of anxiety and distress are important not only as quality-of-life factors, but also because high anxiety may interfere with the understanding and integration of complex genetic and medical information and adherence to screening.[101-103] The limited number of medical interventions with proven benefit to mutation carriers provides further basis for the expectation that mutation carriers may experience increased anxiety, depression, and continuing uncertainty after disclosure of genetic test results.[104] Formal, objective evaluation of these outcomes are now emerging. (Refer to the Emotional Outcomes and Behavioral Outcomes sections of this summary for more information.)

Published descriptions of counseling programs for BRCA1 (and subsequently for BRCA2) testing include strategies for gathering a family history, assessing eligibility for testing, communicating the considerable volume of relevant information about breast/ovarian cancer genetics and associated medical and psychosocial risks and benefits, and discussion of specialized ethical considerations about confidentiality and family communication.[3,105-111] Participant distress, intrusive thoughts about cancer, coping style, and social support were assessed in many prospective testing candidates. The psychosocial outcomes evaluated in these programs have included changes in knowledge about the genetics of breast/ovarian cancer after counseling, risk comprehension, psychological adjustment, family and social functioning, and reproductive and health behaviors.[112] A Dutch study of communication processes and satisfaction levels of counselees going through cancer genetic counseling for inherited cancer syndromes indicated that asking more medical questions (by the counselor), providing more psychosocial information, and longer eye contact by the counselor were associated with lower satisfaction levels. The provision of medical information by the counselor was most highly related to satisfaction and perception that needs have been fulfilled.[113] Additional research is needed on how to adequately address the emotional needs and feelings of control of counselees.

Many of the psychosocial outcome studies involve specialized, highly selected research populations, some of which were utilized to map and clone BRCA1 and BRCA2. One such example is K2082, an extensively studied kindred of more than 800 members of a Utah Mormon family in which a BRCA1 mutation accounts for the observed increased rates of breast and ovarian cancer. A study of the understanding that members of this kindred have about breast/ovarian cancer genetics found that, even in breast cancer research populations, there was incomplete knowledge about associated risks of colon and prostate cancer, the existence of options for risk-reducing mastectomy (RRM) and risk-reducing salpingo-oophorectomy (RRSO), and the complexity of existing psychosocial risks.[3] A meta-analysis of 21 studies found that genetic counseling was effective in increasing knowledge and improved the accuracy of perceived risk. Genetic counseling did not have a statistically significant long-term impact on affective outcomes including anxiety, distress, or cancer-specific worry and the behavioral outcome of cancer surveillance activities.[61] These prospective studies, however, were characterized by a heterogeneity of measures of cancer-specific worry and inconsistent findings in effects of change from baseline.[61]

It is not yet clearly established to what extent findings derived from special research populations, at least some of which have long awaited genetic testing for breast/ovarian cancer risk, are generalizable to other populations. For example, there are data to suggest that the BRCA1/BRCA2 penetrance estimates derived from these dramatically affected families are substantial overestimates and do not apply to most families presenting for counseling and possible testing.[114]

Emotional Outcomes of Individuals

Studies conducted to date of psychological outcomes associated with genetic testing for mutations in breast/ovarian cancer predisposition genes have shown low levels of distress among those found to be carriers and even lower levels among noncarriers.[88,115-118] A systematic review found that the studies assessing measures of distress (9 of 11 studies) found no change, or a decrease, in those parameters (including anxiety, depression, general distress, and situation distress) in people who had undergone testing at assessments done at 1 month or less, and 3 to 6 months later.[119] One follow-up study from the United Kingdom measured levels of cancer-related worry, general mental health, risk perception, intrusive or avoidant thoughts, and risk-management behaviors at baseline and 1, 4, and 12 months after results were provided. This study included 202 unaffected women and 59 unaffected men, of whom 91 tested positive and 170 tested negative. Results showed that while female noncarriers had significant (P < .001) reductions in cancer-related worry, female carriers younger than 50 years had an increase in cancer-related worry 1 month posttesting. These levels returned to baseline by 12 months but remained higher than noncarrier levels throughout the 12-month period. Female carriers engaged in more posttest screening than noncarriers (92% vs. 30%) within 12 months of test results disclosure. Thirty carriers had RRM and/or RRSO within the same time period.[120] A slightly smaller subset of this cohort was assessed again for cancer-related worry, general mental health, and risk-management behaviors 3 years after genetic test result disclosure. Among those who returned the questionnaire were 154 women and 39 males, including 71 carriers and 122 noncarriers. The level of distress and cancer worry was similar between carriers and noncarriers. Female carriers had higher distress levels at 3 years versus 1 year postdisclosure, but their level of cancer worry decreased significantly over the same time period. In female noncarriers, although the level of cancer worry had decreased from baseline to 1 year postdisclosure, these levels returned to baseline by 3 years.[121] The authors did not comment on contextual factors that might influence distress and cancer worry levels. Another study reported that, compared with pretest levels, mean scores on 1-year posttest measures of cancer-specific distress and state-anxiety decreased significantly among noncarriers, while scores on these measures and on a measure of general distress did not change among BRCA1/BRCA2 carriers.[122] One long-term study of 65 female participants explored the psychosocial consequences of carrying a BRCA1/BRCA2 mutation 5 years after genetic testing. Carriers did not differ from noncarriers on several distress measures. Although both groups showed significant increases in depression and anxiety compared with 1 year postdisclosure, these scores remained within normal limits for the general population.[123] Caution is advised by authors of these studies in interpretation of the results as they are all from programs in which results disclosure was preceded by extensive genetic counseling about risks and benefits of BRCA1/BRCA2 testing, psychological assessment, and in some cases exclusion of a few individuals who appeared highly distressed.[3] Intrusive thoughts (measured by the Impact of Event Scale [IES]) [124] about cancer diminished after results disclosure for both mutation-positive and mutation-negative individuals in one Dutch study.[125]

Some studies have examined reactions to BRCA testing several years after the receipt of results. Two U.S.-based studies have reported similar findings among women who were surveyed more than 3 years after receipt of BRCA test results.[126,127] In a cross-sectional study,[126] 167 women who were surveyed more than 4 years after receiving BRCA test results reported low levels of genetic testing–specific concerns, as measured using the Multidimensional Impact of Cancer Risk Assessment Scale.[128] Approximately 74% of women reported no distress; 41% reported no uncertainty about their cancer risk, screening decisions, and options for risk management and prevention; and 51% reported positive experiences suggestive of low adverse reactions pertaining to family support and communication.[126] In multivariate regression models, mutation carriers were significantly more likely to experience distress than were noncarriers. Time since disclosure of test result significantly predicted uncertainty but not distress, such that more time since disclosure corresponded to less uncertainty. In a second study, 464 women were followed prospectively for a median of 5 years (range: 3.4–9.1 years) after testing. Among both affected and unaffected participants, BRCA carriers reported significantly higher levels of distress, uncertainty (affected only), perceived stress (affected only), and lower positive testing experiences (unaffected only) than women who received negative results.[127] Although both studies reported greater distress among BRCA carriers than among noncarriers, the level of distress was not reflective of clinically significant dysfunction.

A prospective Australian study evaluated the psychological impact of genetic testing at baseline, 7 to 10 days, 4 months, and 12 months in 60 women of AJ heritage (10 with breast cancer, 50 unaffected). Of the 43 women who opted to learn their test results, 97% felt pleased to have had the test and, at 12 months of follow-up, none regretted having been tested. Seventeen women opted not to receive their results and had significantly lower levels of breast cancer anxiety than did those who opted to receive their results. Women with no history of cancer who opted to learn their results showed a progressive decrease in breast cancer anxiety over the 12-month study period compared with baseline measures. There was also no statistically significant difference in measures of depression and generalized anxiety from baseline to the follow-up assessments.[129] However, only 7 of 43 women had deleterious mutations, which may influence interpretation of test results.

Despite generally positive findings regarding diminished distress in tested individuals, most studies also report increased distress among small subsets of tested individuals. Most, but not all, of these increases are within the normal range of distress. Increased distress has been noted by individuals receiving both positive and negative test results. Studies suggest that the psychological impact of an individual test result is highly influenced by the test result status of other family members. A 1999 study found that an individual’s response to learning his or her own BRCA1/BRCA2 test result was significantly influenced by his or her gender and by the genetic test result status of other family members. Adverse, immediate outcomes were experienced by male carriers who were the first tested in their family or by noncarrier men whose siblings were all positive. In addition, female carriers who were the first in their families to be tested or whose siblings were all negative had significantly higher distress than other female carriers.[99] Another study found that spousal anxiety about genetic testing and supportiveness differentiated the impact of BRCA1/BRCA2 test results. When the spouse was highly anxious and unsupportive in style, the mutation carrier had significantly higher levels of distress. These studies illustrate that genetic test results are not received in a vacuum, and that researchers need to consider the context of the tested individual in determining which individuals applying for genetic testing may require additional emotional support.[100]

In another study, depression rates postdisclosure were unchanged for mutation carriers and markedly decreased for noncarriers.[46] An analysis of the distress of individuals receiving BRCA1 results in the context of their siblings' results, however, revealed patterns of response suggesting that certain subgroups of tested individuals have markedly increased levels of distress after disclosure that were not apparent when the analysis focused only on comparing the mean scores for carriers versus noncarriers.[99] Early optimistic findings may not sufficiently reflect the true complexity of response to disclosure of BRCA1/BRCA2 test results. Female carriers who had no carrier siblings had distress scores (IES) similar to those found in cancer patients 10 weeks after their diagnosis. The distress of male subjects was highly correlated with the status of their siblings’ test results or lack thereof.[99] One pilot study suggested that women diagnosed more recently were more distressed after counseling.[130] A survey of women enrolled in a high-risk clinic found that heightened levels of distress may be more related to living with the awareness of a familial risk of cancer than with the genetic testing process itself. Obtaining genetic testing may be less stressful than living with the awareness of familial risk of cancer.[131] (Refer to the PDQ Supportive Care summaries on Depression and Adjustment to Cancer: Anxiety and Distress for more detailed information about depression and anxiety associated with a cancer diagnosis.) Case descriptions have supported the importance of family relationships and test outcomes in shaping the distress of tested individuals.[132,133]

Although there are not yet reports of large-scale studies of the reactions of affected individuals to genetic testing, there are indications from several smaller studies that affected individuals who undergo genetic counseling and testing experience more distress than had been expected by professionals [134,135] and are less able themselves to anticipate the intensity of their reactions after result disclosure.[136] Female mutation carriers who have had breast cancer are often surprised by their high risk of ovarian cancer. Women mutation carriers who have had breast cancer worried more than unaffected women about developing ovarian cancer, though, in general, worry about ovarian cancer risk was found to be unrealistically low.[135] In addition, some distress related to the burden of conveying genetic information to relatives has been noted among those who are the first in their families to be tested.[134,137]

The long-term effect of uninformative BRCA1/BRCA2 test results (BRCA1/BRCA2 negative, negative on a panel of three Ashkenazi founder mutations, or detecting a variant of uncertain significance) was examined in 209 women recruited from one of two comprehensive cancer centers or a community hospital.[138] These women had a personal history of breast or ovarian cancer and were assessed at pretesting, 1-, 6-, and 12-months postdisclosure. Distress was low at each time point, and declined from pretest to post-disclosure, remaining stable and low thereafter. No clinical cut-offs were reported. Those who reported higher general distress associated with cancer risk, risk-reduction efforts, and family communication and lower confidence in dealing with these issues, and those who expected to carry a deleterious mutation, had greater decisional conflict related to managing their cancer risk through 1-year posttest. In another study of 182 women drawn from this sample, most (84%) had made a risk management decision within 6 months of test result disclosure. Those who were delayed in making a risk management decision reported greater feelings of decisional uncertainty, dissatisfaction, and lack of confidence, yet there was also a high level of reported decisional conflict even among those who were early or intermediate decision-makers. Increased depression levels postdisclosure predicted increased risk of delay in risk management decision-making.[139]

Several studies have compared the provision of breast cancer genetics services by different providers and the psychological impact on women at high and low risk of cancer. In a study of 735 women at all hereditary breast/ovarian cancer risk levels, the services of a multidisciplinary team of genetics specialists was compared with services provided by surgeons. There were no significant differences between groups in anxiety, cancer worry, or perceived risk.[140] In a Scottish study of 373 participants, an alternative model of cancer genetics services using genetics nurse specialists in community-based services was compared with standard genetics regional services. There was no difference in cancer worry or change in health behaviors between the two groups. Cancer worry decreased for both groups over a 6-month period. Women who dropped out of the study tended to be in the nurse provider arm or were at low risk of breast cancer.[141] In a small U.S. study, an evaluation of nurses and genetic counselors as providers of education about breast cancer susceptibility testing was conducted to compare outcomes of pretest education about breast cancer susceptibility. Four genetic counselors and two nurses completed specialized training in cancer genetics. Women receiving pretest education from nurses were as satisfied with information received and had equal degrees of perceived autonomy and partnership. The study findings suggest that with proper training and supervision, both genetic counselors and nurses can be effective in providing pretest education to women considering genetic susceptibility testing for breast cancer risk.[142]

There has been little empirical research in the communication of risk assessments to individuals at risk of breast/ovarian cancer syndromes. When asked to choose a preferred method, individuals undergoing genetic counseling for breast and ovarian cancer appear to prefer quantitative to qualitative presentation of risk information.[143,144] One study indicated that most women wanted information given both ways.[68] Information about the risk of developing breast cancer among women with a family history of breast cancer may be more accurately recalled when presented as odds ratios (ORs), rather than in other forms.[145]

There is a small but growing body of literature on the use of decision aids as an adjunct to standard genetic counseling to assist patients in making informed decisions about genetic testing. One study measured the effectiveness of a decision aid for BRCA1/BRCA2 genetic testing given to women at the end of their first genetic counseling consultation. At 1 week and 6 months follow-up, the decision aid had no effect on informed choice, decisional regret, or actual genetic testing decision. However, women who received the decision aid had significantly higher knowledge levels and felt more informed about genetic testing than women who received the control pamphlet. The decision aid also helped those women who did not have their blood drawn for genetic testing at the first visit to clarify their values about their testing decision.[146]

Preferences for delivery of breast cancer genetic testing are reported in one study [144] to include pretest counseling conducted by a genetic counselor (42%) or oncologist (22%) rather than by a primary care physician (6%), nurse (12%), or gynecologist (5%). Patients in that study preferred results disclosure by an oncologist. Younger women especially expressed a need for individual consideration of their personal values and goals or potential emotional reactions to testing; 67% believed emotional support and counseling were a necessary part of posttest counseling. Most women (82%) wanted to be able to self-refer for genetic testing, without a physician referral.

Family Effects

Family communication about genetic testing and hereditary risk

Family communication about genetic testing for cancer susceptibility, and specifically about the results of BRCA1/BRCA2 genetic testing, is complex; there are few systematic data available on this topic. Gender appears to be an important variable in family communication and psychological outcomes. One study documented that female carriers are more likely to disclose their status to other family members (especially sisters and children aged 14–18 years) than are male carriers.[147] Among males, noncarriers were more likely than carriers to tell their sisters and children the results of their tests. BRCA1/BRCA2 carriers who disclosed their results to sisters had a slight decrease in psychological distress, compared with a slight increase in distress for carriers who chose not to tell their sisters. One study found that men reported greater difficulty disclosing mutation-positive results to family members than women (90% vs. 70%).[148]

Family communication of BRCA1/BRCA2 test results to relatives is another factor affecting participation in testing. There have been more studies of communication with first-degree relatives and second-degree relatives than with more distant family members. One study investigated the process and content of communication among sisters about BRCA1/BRCA2 test results.[149] Study results suggest that both mutation carriers and women with uninformative results communicate with sisters to provide them with genetic risk information. Among relatives with whom genetic test results were not discussed, the most important reason given was that the affected women were not close to their relatives. Studies found that women with a BRCA mutation more often shared their results with their mother and adult sisters and daughters than with their father and adult brothers and sons.[78,150-153] A study that evaluated communication of test results to first-degree relatives at 4 months postdisclosure found that women aged 40 years or older were more likely to inform their parents of test results compared with younger women. Participants also were more likely to inform brothers of their results if the BRCA mutation was inherited through the paternal line.[151] Another study found that disclosure was limited mainly to first-degree relatives, and dissemination of information to distant relatives was problematic.[154] Age was a significant factor in informing distant relatives with younger patients being more willing to communicate their genetic test result.[149,150,154]

A few in-depth qualitative studies have looked at issues associated with family communication about genetic testing. Although the findings from these studies may not be generalizable to the larger population of at-risk persons, they illustrate the complexity of issues involved in conveying hereditary cancer risk information in families.[155] On the basis of 15 interviews conducted with women attending a familial cancer genetics clinic, the authors concluded that while women felt a sense of duty to discuss genetic testing with their relatives, they also experienced conflicting feelings of uncertainty, respect, and isolation. Decisions about whom in the family to inform and how to inform them about hereditary cancer and genetic testing may be influenced by tensions between women's need to fulfill social roles and their responsibilities toward themselves and others.[155] Another qualitative study of 21 women who attended a familial breast and ovarian cancer genetics clinic suggested that some women may find it difficult to communicate about inherited cancer risk with their partners and with certain relatives, especially brothers, because of those persons’ own fears and worries about cancer.[153] This study also suggested that how genetic risk information is shared within families may depend on the existing norms for communicating about cancer in general. For example, family members may be generally open to sharing information about cancer with each other, may selectively avoid discussing cancer information with certain family members to protect themselves or other relatives from negative emotional reactions, or may ask a specific relative to act as an intermediary to disclosure of information to other family members.[156] The potential importance of persons outside the family, such as friends, as both confidantes about inherited cancer risk information and as sources of support for coping with this information was also noted in the study.[153]

A study of 31 mothers with a documented BRCA mutation explored patterns of dissemination to children.[157] Of those who chose to disclose test results to their children, age of offspring was the most important factor. Fifty percent of the children who were told were aged 20 to 29 years and slightly more than 25% of the children were aged 19 years or younger. Sons and daughters were notified in equal numbers. More than 70% of mothers informed their children within a week of learning their test result. Ninety-three percent of mothers who chose not to share their results with their children indicated that it was because their children were too young. These findings were consistent with three other studies showing that children younger than 13 years were less likely to be informed about test results compared with older children.[151,158,159] Another study of 187 mothers undergoing BRCA1/BRCA2 testing evaluated their need for resources to prepare for a facilitated conversation about sharing their BRCA1/BRCA2 testing results with their children. Seventy-eight percent of mothers were interested in three or more resources, including literature (93%), family counseling (86%), talk to prior participants (79%), and support groups (54%).[158]

A longitudinal study of 153 women self-referred for genetic testing for BRCA1 and BRCA2 mutations and 118 of their partners evaluated communication about genetic testing and distress before testing and at 6 months posttesting.[160] The study found that most couples discussed the decision to undergo testing (98%), most test participants felt their partners were supportive, and most women disclosed test results to their partners (97%, n = 148). Test participants who felt their partners were supportive during pretest discussions experienced less distress after disclosure, and partners who felt more comfortable sharing concerns with test participants pretest experienced less distress after disclosure. Six-month follow-up revealed that 22% of participants felt the need to talk about the testing experience with their partners in the week before the interview. Most participants (72%, n = 107) reported comfort in sharing concerns with their partners, and 5% (n = 7) reported relationship strain as a result of genetic testing. In couples in which the woman had a positive genetic test result, more relationship strain, more protective buffering of their partners, and more discussion of related concerns were reported than in couples in which the woman had a true-negative or uninformative result.[160]

There is a small but growing body of literature regarding psychological effects in men who have a family history of breast cancer and who are considering or have had BRCA testing. A qualitative study of 22 men from 16 high-risk families in Ireland revealed that more men in the study with daughters were tested than men without daughters. These men reported little communication with relatives about the illness, with some men reporting being excluded from discussion about cancer among female family members. Some men in the study also reported actively avoiding open discussion with daughters and other relatives.[161] In contrast, a study of 59 men testing positive for a BRCA1/BRCA2 mutation found that most men participated in family discussions about breast and/or ovarian cancer. However, fewer than half of the men participated in family discussions about risk-reducing surgery. The main reason given for having BRCA testing was concern for their children and a need for certainty about whether they could have transmitted the mutation to their children. In this study, 79% of participating men had at least one daughter. Most of these men described how their relationships had been strengthened after receipt of BRCA results, helping communication in the family and greater understanding.[162] Men in both studies expressed fears of developing cancer themselves. Irish men especially reported fear of cancer in sexual organs.

Family functioning

One study assessed 212 individuals from 13 hereditary breast and ovarian cancer families who received genetic counseling and were offered BRCA1/BRCA2 testing for documented mutation in the family. Individuals who were not tested were found 6 to 9 months later to have significantly greater increases in family expressiveness and cohesiveness compared with those who were tested. Persons who were randomly assigned to a client-centered versus problem-solving genetic counseling intervention had a significantly greater reduction in conflict, regardless of the test decision.[49]

Partners of high-risk women

Many studies have looked at the psychological effects in women of having a high risk of developing cancer, either on the basis of carrying a BRCA1/BRCA2 mutation or having a strong family history of cancer. Some studies have also examined the effects on the partners of such women.

A Canadian study assessed 59 spouses of women found to have a BRCA1/BRCA2 mutation. All were supportive of their spouses’ decision to undergo genetic testing and 17% wished they had been more involved in the genetic testing process. Spouses who reported that genetic testing had no impact on their relationship had long-term relationships (mean duration 27 years). Forty-six percent of spouses reported that their major concern was of their partner dying of cancer. Nineteen percent were concerned their spouse would develop cancer and 14% were concerned their children would also be BRCA1/BRCA2 mutation carriers.[163]

In a U.S. study, 118 partners of women who underwent genetic testing for mutations in BRCA1 and BRCA2 completed a survey before testing and then again 6 months after result disclosure. At 6 months, only 10 partners reported that they had not been told of the test result. Ninety-one percent reported that the testing had not caused strain on their relationship. Partners who were comfortable sharing concerns before testing experienced less distress after testing. Protective buffering was not found to impact distress levels of partners.[160]

An Australian study of 95 unaffected women at high risk of developing breast and/or ovarian cancer (13 mutation carriers and 82 with unknown mutation status) and their partners showed that although the majority of male partners had distress levels comparable to a normative population sample, 10% had significant levels of distress that indicated the need for further clinical intervention. Men with a high monitoring coping style and greater perceived breast cancer risk for their wives reported higher levels of distress. Open communication between the men and their partners and the occurrence of a cancer-related event in the wife’s family in the last year were associated with lower distress levels. When men were asked what kind of information and support they would like for themselves and their partners, 57.9% reported that they would like more information about breast and ovarian cancer, and 32.6% said they would like more support in dealing with their partner's risk. Twenty-five percent of men had suggestions on how to improve services for partners of high-risk women, including strategies on how to best support their partner, greater encouragement from health care professionals to attend appointments, and meeting with other partners.[164]

A review of this literature reported that the BRCA testing process may be distressing for male partners, particularly for those with spouses identified as carriers. Male partner distress appears to be associated with their beliefs about the woman’s breast cancer risk, lack of couple communication, and feelings of alienation from the testing process.[165]

At-risk males

A review of the literature on the experiences of males in BRCA1 and BRCA2 mutation–positive families reported that while the data are limited, men from mutation-positive families are less likely than females to participate in communication regarding genetics at every level, including the counseling and testing process. Men are less likely to be informed of genetic test results received by female relatives, and most men from these families do not pursue their own genetic testing.[166]

A study of Dutch men at increased risk of having inherited a BRCA1 mutation reported a tendency for the men to deny or minimize the emotional effects of their risk status, and to focus on medical implications for their female relatives. Men in these families, however, also reported considerable distress in relation to their female relatives.[167] In another study of male psychological functioning during breast cancer testing, 28 men belonging to 18 different high-risk families (with a 25% or 50% risk of having inherited a BRCA1/BRCA2 mutation) participated. The study purpose was to analyze distress in males at risk of carrying a BRCA1/BRCA2 mutation who applied for genetic testing. Of the men studied, most had low pretest distress; scores were lowest for men who were optimistic or who did not have daughters. Most mutation carriers had normal levels of anxiety and depression and reported no guilt, though some anticipated increased distress and feelings of responsibility if their daughters developed breast or ovarian cancer. None of the noncarriers reported feeling guilty.[168] In one study,[162] adherence to recommended screening guidelines after testing was analyzed. In this study, more than half of male carriers of mutations did not adhere to the screening guidelines recommended after disclosure of genetic test results. These findings are consistent with those for female carriers of BRCA1/BRCA2 mutations.[162,169]

A multicenter U.K. cohort study examined prospective outcomes of BRCA1/BRCA2 testing in 193 individuals, of which 20% were men aged 28 to 86 years. Men’s distress levels were low, did not differ among carriers and noncarriers, and did not change from baseline (before genetic testing) to the 3-year follow-up. Twenty-two percent of male mutation carriers received colorectal cancer screening and 44% received prostate cancer screening;[121] however, it is unclear whether men in this study were following age-appropriate screening guidelines.

Children

Several studies have explored communication of BRCA test results to at-risk children. Across all studies, the rate of disclosure to children ranging in age from 4 to 25 years is approximately 50%.[150,151,154,158,170-173] In general, age of offspring was the most important factor in deciding whether to disclose test results. In one study of 31 mothers disclosing their BRCA test results, 50% of the children who were informed of the results were aged 20 to 29 years and slightly more than 25% of the children were aged 19 years or younger. Sons and daughters were notified in equal numbers.[157] Similarly, in another study of 42 female BRCA mutation carriers, 83% of offspring older than age 18 years were told of the results, while only 21% of offspring aged 13 years or younger were told.[158]

Several studies have also looked at the timing of disclosure to children after parents receive their test results. Although the majority of children were told within a week to several months after results disclosure,[151,157,158] some parents chose to delay disclosure.[158] Reasons for delaying disclosure included waiting for the child to get older, allowing time for the parent to adjust to the information, and waiting until results could be shared in person (in the case of adult children living away from home).[158]

One study looked at the reaction of children to results disclosure or the effect on the parent-child relationship of communicating the results.[158] With regard to offspring’s understanding of the information, almost half of parents from one study reported that their child did not appear to understand the significance of a positive test result, although older children were reported to have a better understanding. This same study also showed that 48% of parents reported at least one negative reaction in their child, ranging from anxiety or concern (22%) to crying and fear (26%). It should be noted, however, that in this study children's level of understanding and reactions to the test result were measured qualitatively and based only on the parents' perception. Also, given the retrospective design of the study, there was a potential for recall bias. There were no significant differences in emotional reaction depending on age or gender of the child. Lastly, 65% of parents reported no change in their relationship with their child, while 5 parents (22%) reported a strengthening of their relationship.

Another study of 187 mothers undergoing BRCA1/BRCA2 testing evaluated their need for resources to prepare for a facilitated conversation about sharing their BRCA1/BRCA2 testing results with their children. Seventy-eight percent of mothers were interested in three or more resources, including literature (93%), family counseling (86%), talking to prior participants (79%), and support groups (54%).[174]

Testing for BRCA1/BRCA2 has been almost universally limited to adults older than 18 years. The risks of testing children for adult-onset disorders (such as breast and ovarian cancer), as inferred from developmental data on children’s medical understanding and ability to provide informed consent, have been outlined in several reports.[50-53] Surveys of parental interest in testing children for adult-onset hereditary cancers suggest that parents are more eager to test their children than to be tested themselves for a breast cancer gene, suggesting potential conflicts for providers.[175,176] In a general population survey in the United States, 71% of parents said that it was moderately, very, or extremely likely that if they carried a breast-cancer predisposing mutation, they would test a 13-year-old daughter now to determine her breast cancer gene status.[175] To date, no data exist on the testing of children for BRCA1/BRCA2, though some researchers believe it is necessary to test the validity of assumptions underlying the general prohibition of testing of children for breast/ovarian cancer and other adult-onset disease genes.[56-58] In one study, 20 children (aged 11–17 years) of a selected group of mothers undergoing genetic testing (80% of whom previously had breast cancer and all of whom had discussed BRCA1/BRCA2 testing with their children) completed self-report questionnaires on their health beliefs and attitudes toward cancer, feelings related to cancer, and behavioral problems.[59] Ninety percent of children thought they would want cancer risk information as adults; half worried about themselves or a family member developing cancer. There was no evidence of emotional distress or behavioral problems. Another study by this group [172] found that 1 month after disclosure of BRCA1/BRCA2 genetic test results, 53% of 42 enrolled mothers of children aged 8 to 17 years had discussed their result with one or more of their children. Age of the child rather than mutation status of the mother influenced whether they were told, as did family health communication style.

In one study, participants who told children younger than 13 years about their carrier status had increased distress, and those who did not tell their young children experienced a slight decrease in distress. Communication with young children was found to be influenced by developmental variables such as age and style of parent/child communication.[172]

Prenatal diagnosis and preimplantation genetic diagnosis

The possibility of transmitting a mutation to a child may pose a concern to families affected by history of breast/ovarian cancer (HBOC),[177] perhaps to the extent that some carriers may avoid childbearing.[178,179] These concerns also may prompt women to consider using prenatal diagnosis methods to help reduce the risk of transmission.[177,180] Prenatal diagnosis is an encompassing term used to refer to any medical procedure conducted to assess the presence of a genetic disorder in a fetus. Methods include amniocentesis and chorionic villous sampling (CVS).[181,182] Both procedures carry some risk of miscarriage and some evidence suggests fetal defects may result from using these tests.[181,182] Moreover, discovering the fetus is a carrier for a genetic defect may impose a difficult decision for couples regarding pregnancy continuation or termination. An alternative to these tests is preimplantation genetic diagnosis (PGD), a procedure used to test fertilized embryos for genetic disorders before uterine implantation,[177,183,184] thereby avoiding the potential dangers associated with amniocentesis and CVS and the decision to terminate a pregnancy. Using the information obtained from the genetic testing, potential parents can decide whether or not to implant. PGD can be used to detect mutations in hereditary cancer predisposing genes, including BRCA.[177,180]

In the United States, a series of studies have evaluated awareness, interest (e.g., would consider using PGD), and attitudes related to PGD among members of Facing Our Risk of Canc