Individuals With Little to Gain from Screening
Women with limited life expectancy
Achieving balance between the benefits and harms of screening is especially important for women with a life expectancy of 5 years or less. Such women might have end-stage renal disease, severe dementia, terminal cancer, or severe comorbid disease with functional dependencies in activities of daily living. Early cancer detection and prompt treatment are unlikely to reduce morbidity or mortality within a woman's 5 years of expected survival, but the negative consequences of screening will occur immediately. Abnormal screening may trigger additional testing, with the attendant anxiety. In particular, the detection of a low-risk malignancy would probably result in a recommendation for treatment, which could impair rather than improve quality of life, without improving survival. Despite these considerations, many women with poor life expectancy due to age or health status often undergo screening mammography. A sizable proportion of patients with advanced cancer continue to undergo cancer screening tests that do not have a meaningful likelihood of providing benefit. For example, among women with advanced cancer compared with controls, at least one screening mammogram was received by 8.9% (95% confidence interval [CI], 8.6%–9.1%) versus 22.0% (95% CI, 21.7%–22.5%).
Screening mammography in women older than 65 years often results in additional diagnostic testing in 85 per 1,000 women, with cancer diagnosed in nine women. The testing is often accomplished over many months, which may cause anxiety. While screening mammography may yield cancer diagnoses in approximately 1% of elderly women, many of these cancers are low risk. A study of California Medicare beneficiaries aged 65 to 79 years demonstrated this clearly. The relative risk (RR) of detecting localized breast cancer was 3.3 (95% CI, 3.1–3.5) among screened women. Diagnosis of metastatic cancer was reduced among screened women (RR, 0.57), suggesting a benefit of mammography screening in elderly women, although it comes with an increased risk of overdiagnosis.
There is no evidence for performing screening mammography in average-risk women younger than 40 years.
Approximately 1% of all breast cancers occur in men. Most cases are diagnosed during the evaluation of palpable lesions, which are generally easy to detect. Treatment consists of surgery, radiation, and systemic adjuvant hormone therapy or chemotherapy. Because of the rarity of the disease, it is extremely unlikely that any screening modality would be useful.
Individuals at Increased Risk of Breast Cancer and Thus Possibly With More to Gain From Screening
Women who have received thoracic radiation
Screening for breast cancer has been recommended for women exposed to therapeutic radiation to the chest, especially if they were exposed at an early age. One systematic review of observational studies of women exposed to large doses (≥20 Gy) of chest radiation before age 30 years found standardized incidence ratios of 13.3 to 55.5 for breast cancer, with no plateau with increasing age. Screening mammography and magnetic resonance imaging can identify early-stage cancers in these women, but the benefits and risks have not been clearly defined.
Although age-adjusted breast cancer incidence rates are higher in white women than in black women, mortality rates are higher in black women. Among breast cancer cases diagnosed from 2004 to 2010, 62% of white women and only 52% of black women had localized disease. The 5-year relative survival rate for localized disease was 99.1% for white women and 94.0% for black women; for regional disease, it was 86.0% for white women and 74.6% for black women; and for distant disease, it was 26.2% for white women and 16.4% for black women. Both breast cancer incidence and mortality are lower among Hispanic and Asian/Pacific Islander women than among white and black women. Survival in black women may be worse than in white women at least in part because of a higher frequency of adverse histologic features, such as a triple-negative phenotype.
Several explanations for these findings have been proposed, including lower socioeconomic status, lower level of education, and less access to screening and treatment services. Population-based studies demonstrate that, compared with other groups, Medicaid recipients and uninsured patients of all races have later-stage breast cancer diagnosis, and survival from the time of diagnosis is shorter. These differences are associated with socioeconomic status and may reflect lack of participation in screening activities.[8,9] Black women older than 65 years are less likely to undergo mammogram screening. Among regular users of mammography, however, cancer was diagnosed in black and white women at similar stages.
Similar studies of Hispanic populations have been conducted. Breast cancer stage at diagnosis in San Diego County, California, was more advanced for Hispanic women than for white women, especially for those younger than 50 years. Low-income whites were more likely to have late-stage diagnosis than high-income whites. Among Hispanic women, there was no difference according to income, but all the Hispanic groups were at or below the lowest white income level. In New Mexico, a population-based case-control study examined the reproductive histories of 719 Hispanic and 836 white breast cancer patients, with half of each group having breast cancer. The Hispanic women had higher body mass index, higher parity, and earlier pregnancies. Whereas reproductive factors such as age at first full-term birth, parity, and duration of lactation accounted for some of the ethnic differences in breast cancer incidence for postmenopausal women, there was no evidence that these factors played a role in the differences for premenopausal patients. A study of mammography screening in an Albuquerque health maintenance organization found that Hispanic women had consistently lower rates of screening than did whites (50.6% vs. 65.5% in 1989, and 62.7% vs. 71.6% in 1996). Predictors of more advanced stage at diagnosis included Hispanic race (odds ratio, 2.12) and younger age.
- Walter LC, Lindquist K, Covinsky KE: Relationship between health status and use of screening mammography and Papanicolaou smears among women older than 70 years of age. Ann Intern Med 140 (9): 681-8, 2004. [PUBMED Abstract]
- Sima CS, Panageas KS, Schrag D: Cancer screening among patients with advanced cancer. JAMA 304 (14): 1584-91, 2010. [PUBMED Abstract]
- Welch HG, Fisher ES: Diagnostic testing following screening mammography in the elderly. J Natl Cancer Inst 90 (18): 1389-92, 1998. [PUBMED Abstract]
- Smith-Bindman R, Kerlikowske K, Gebretsadik T, et al.: Is screening mammography effective in elderly women? Am J Med 108 (2): 112-9, 2000. [PUBMED Abstract]
- Henderson TO, Amsterdam A, Bhatia S, et al.: Systematic review: surveillance for breast cancer in women treated with chest radiation for childhood, adolescent, or young adult cancer. Ann Intern Med 152 (7): 444-55; W144-54, 2010. [PUBMED Abstract]
- Howlader N, Noone AM, Krapcho M, et al., eds.: SEER Cancer Statistics Review, 1975-2011. Bethesda, Md: National Cancer Institute, 2014. Also available online. Last accessed February 6, 2015.
- Bauer KR, Brown M, Cress RD, et al.: Descriptive analysis of estrogen receptor (ER)-negative, progesterone receptor (PR)-negative, and HER2-negative invasive breast cancer, the so-called triple-negative phenotype: a population-based study from the California cancer Registry. Cancer 109 (9): 1721-8, 2007. [PUBMED Abstract]
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- Bradley CJ, Given CW, Roberts C: Race, socioeconomic status, and breast cancer treatment and survival. J Natl Cancer Inst 94 (7): 490-6, 2002. [PUBMED Abstract]
- McCarthy EP, Burns RB, Coughlin SS, et al.: Mammography use helps to explain differences in breast cancer stage at diagnosis between older black and white women. Ann Intern Med 128 (9): 729-36, 1998. [PUBMED Abstract]
- Bentley JR, Delfino RJ, Taylor TH, et al.: Differences in breast cancer stage at diagnosis between non-Hispanic white and Hispanic populations, San Diego County 1988-1993. Breast Cancer Res Treat 50 (1): 1-9, 1998. [PUBMED Abstract]
- Gilliland FD, Hunt WC, Baumgartner KB, et al.: Reproductive risk factors for breast cancer in Hispanic and non-Hispanic white women: the New Mexico Women's Health Study. Am J Epidemiol 148 (7): 683-92, 1998. [PUBMED Abstract]
- Frost FJ, Tollestrup K, Trinkaus KM, et al.: Mammography screening and breast cancer tumor size in female members of a managed care organization. Cancer Epidemiol Biomarkers Prev 7 (7): 585-9, 1998. [PUBMED Abstract]