Description of the Evidence
Breast cancer incidence and mortality
Breast cancer is the most common noncutaneous cancer in U.S. women, with an estimated 62,570 cases of in situ disease, 232,670 new cases of invasive disease, and 40,000 deaths expected in 2014. Thus, fewer than 1 of 6 women diagnosed with breast cancer die of the disease. By comparison, about 72,330 American women are estimated to die of lung cancer in 2014. Males account for 1% of breast cancer cases and breast cancer deaths (refer to the Special Populations section of this summary for more information).
Widespread adoption of screening increases breast cancer incidence in a given population and changes the characteristics of cancers detected, with increased incidence of lower-risk cancers, premalignant lesions, and ductal carcinoma in situ (DCIS). (Refer to the Ductal Carcinoma In Situ section in the Breast Cancer Diagnosis and Pathology section of this summary for more information.) Ecologic studies from the United States  and the United Kingdom  demonstrate an increase in DCIS and invasive breast cancer incidence since the 1970s, attributable to the widespread adoption of both postmenopausal hormone therapy and screening mammography. In the last decade, women have refrained from using postmenopausal hormones, and breast cancer incidence has declined, but not to the levels seen prior to the widespread use of screening mammography.
One might expect that if screening identifies cancers before they cause clinical symptoms, then the period of screening will be followed by a period of compensatory decline in cancer rates, either in annual population incidence rates or in incidence rates in older women. However, no compensatory drop in incidence rates has ever been seen following the adoption of screening, suggesting that screening leads to overdiagnosis—the identification of clinically insignificant cancers (refer to the Overdiagnosis section in the Harms of Screening Mammography section of this summary for more information).
Breast cancer incidence and mortality risk also vary according to geography, culture, race, ethnicity, and socioeconomic status (refer to the Special Populations section of this summary for more information).
Risk Factors for Breast Cancer
Breast cancer risk is affected by many factors besides participation in screening activities. Understanding and quantifying these risks is important to a woman, to her physicians, and to public policy makers.
|Current Age (in Years)||Risk in Next 10 Years||Lifetime Risk of a Breast Cancer Diagnosis|
|aAdapted from Altekruse et al.|
|30||1 in 250||1 in 8|
|40||1 in 71||1 in 9|
|50||1 in 42||1 in 9|
|60||1 in 29||1 in 11|
|70||1 in 27||1 in 15|
The incidence of breast cancer increases with a woman's age. As shown in Table 1, a 60-year-old woman has a higher risk of being diagnosed with breast cancer in the next 10 years than does a 40-year-old woman.
The cumulative lifetime incidence decreases with advancing age because the longer a woman lives without a breast cancer diagnosis, the lower her lifetime risk compared to a younger woman who might develop breast cancer at a younger or older age. The commonly quoted risk of one in eight women who will be diagnosed with breast cancer is based on lifetime risk of a diagnosis (not death) starting from birth and does not account for the woman’s current age.
Breast cancer mortality increases with age. For a 40-year-old woman without a breast cancer diagnosis, the chance of dying from breast cancer within the next 10 years is extremely small, but for a woman older than 65, it is about 1%. For a woman older than 70, the risk of dying of breast cancer is even higher, but the risk of dying of any cause is higher yet.
Personal history of breast cancer
Women with a personal history of invasive breast cancer, DCIS, or lobular carcinoma in situ also have an increased risk of being diagnosed with a new primary breast cancer. Recommendations for subsequent mammograms vary, but evidence for various strategies is scant.
Prior radiation therapy
Women treated with thoracic radiation before the age of 30 years have a 1% annual risk of breast cancer, starting 8 years after the irradiation and for the rest of their lives.[7,8] Annual screening with magnetic resonance imaging (MRI) has been proposed in such women, beginning 8 years after treatment or by age 25 years, whichever is later. In a study of screening with mammography and MRI, 13 cancers were diagnosed among 98 asymptomatic women who received a chest radiation dose of 15 Gy or less for pediatric or adult cancer. Four of those cancers would not have been detected without the use of MRI. Another study of multiple screening modalities observed a similar increase in cancer detection with the addition of MRI. These data suggest that earlier detection is possible with MRI, but do not demonstrate a definitive benefit of adjunct MRI screening.
Dense breast tissue
Women with radiologically dense breasts (heterogeneously dense or extremely dense in the terminology of the Breast Imaging Reporting and Data System [BI-RADS]) [12-15] have a threefold to sixfold increased risk of breast cancer compared with women who have fatty breasts.
Other risk factors and risk prediction models
Other risk factors for breast cancer include an inherited predisposition (BRCA1 or BRCA2, and others); early age at menarche and late age at first birth; and previous breast biopsies showing benign proliferative breast disease.[17-19] Menopausal hormone use, obesity, lack of physical activity, and alcohol intake are associated with an increased risk of breast cancer. (Refer to the PDQ summaries on Cancer Prevention Overview and Breast Cancer Prevention for more information.) Several models estimate an individual woman's risk based on these and other factors.[20-23] (Refer to the PDQ summary on Genetics of Breast and Gynecologic Cancers for more information.)
- American Cancer Society: Cancer Facts and Figures 2014. Atlanta, Ga: American Cancer Society, 2014. Available online. Last accessed November 24, 2014.
- Altekruse SF, Kosary CL, Krapcho M, et al.: SEER Cancer Statistics Review, 1975-2007. Bethesda, Md: National Cancer Institute, 2010. Also available online. Last accessed October 3, 2014.
- Johnson A, Shekhdar J: Breast cancer incidence: what do the figures mean? J Eval Clin Pract 11 (1): 27-31, 2005. [PUBMED Abstract]
- Haas JS, Kaplan CP, Gerstenberger EP, et al.: Changes in the use of postmenopausal hormone therapy after the publication of clinical trial results. Ann Intern Med 140 (3): 184-8, 2004. [PUBMED Abstract]
- Kerlikowske K, Salzmann P, Phillips KA, et al.: Continuing screening mammography in women aged 70 to 79 years: impact on life expectancy and cost-effectiveness. JAMA 282 (22): 2156-63, 1999. [PUBMED Abstract]
- Houssami N, Abraham LA, Miglioretti DL, et al.: Accuracy and outcomes of screening mammography in women with a personal history of early-stage breast cancer. JAMA 305 (8): 790-9, 2011. [PUBMED Abstract]
- Goss PE, Sierra S: Current perspectives on radiation-induced breast cancer. J Clin Oncol 16 (1): 338-47, 1998. [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]
- Saslow D, Boetes C, Burke W, et al.: American Cancer Society guidelines for breast screening with MRI as an adjunct to mammography. CA Cancer J Clin 57 (2): 75-89, 2007 Mar-Apr. [PUBMED Abstract]
- Freitas V, Scaranelo A, Menezes R, et al.: Added cancer yield of breast magnetic resonance imaging screening in women with a prior history of chest radiation therapy. Cancer 119 (3): 495-503, 2013. [PUBMED Abstract]
- Terenziani M, Casalini P, Scaperrotta G, et al.: Occurrence of breast cancer after chest wall irradiation for pediatric cancer, as detected by a multimodal screening program. Int J Radiat Oncol Biol Phys 85 (1): 35-9, 2013. [PUBMED Abstract]
- ACR BI-RADS Breast Imaging and Reporting Data System: Breast Imaging Atlas. Vol. 1: Mammography. 4th ed. Reston, Va: American College of Radiology, 2003. Also available online. Last accessed October 30, 2014.
- Ma L, Fishell E, Wright B, et al.: Case-control study of factors associated with failure to detect breast cancer by mammography. J Natl Cancer Inst 84 (10): 781-5, 1992. [PUBMED Abstract]
- Goodwin PJ, Boyd NF: Mammographic parenchymal pattern and breast cancer risk: a critical appraisal of the evidence. Am J Epidemiol 127 (6): 1097-108, 1988. [PUBMED Abstract]
- Fajardo LL, Hillman BJ, Frey C: Correlation between breast parenchymal patterns and mammographers' certainty of diagnosis. Invest Radiol 23 (7): 505-8, 1988. [PUBMED Abstract]
- Harvey JA, Bovbjerg VE: Quantitative assessment of mammographic breast density: relationship with breast cancer risk. Radiology 230 (1): 29-41, 2004. [PUBMED Abstract]
- London SJ, Connolly JL, Schnitt SJ, et al.: A prospective study of benign breast disease and the risk of breast cancer. JAMA 267 (7): 941-4, 1992. [PUBMED Abstract]
- McDivitt RW, Stevens JA, Lee NC, et al.: Histologic types of benign breast disease and the risk for breast cancer. The Cancer and Steroid Hormone Study Group. Cancer 69 (6): 1408-14, 1992. [PUBMED Abstract]
- Jacobs TW, Byrne C, Colditz G, et al.: Radial scars in benign breast-biopsy specimens and the risk of breast cancer. N Engl J Med 340 (6): 430-6, 1999. [PUBMED Abstract]
- Gail MH, Brinton LA, Byar DP, et al.: Projecting individualized probabilities of developing breast cancer for white females who are being examined annually. J Natl Cancer Inst 81 (24): 1879-86, 1989. [PUBMED Abstract]
- Bondy ML, Lustbader ED, Halabi S, et al.: Validation of a breast cancer risk assessment model in women with a positive family history. J Natl Cancer Inst 86 (8): 620-5, 1994. [PUBMED Abstract]
- Spiegelman D, Colditz GA, Hunter D, et al.: Validation of the Gail et al. model for predicting individual breast cancer risk. J Natl Cancer Inst 86 (8): 600-7, 1994. [PUBMED Abstract]
- Amir E, Freedman OC, Seruga B, et al.: Assessing women at high risk of breast cancer: a review of risk assessment models. J Natl Cancer Inst 102 (10): 680-91, 2010. [PUBMED Abstract]