gynecology and obstetrics
Breast Cancer Screening and Prevention
Screening for Breast Cancer
Screening modalities include Mammography (including digital and 3-dimensional) Clinical breast examination (CBE) by a health care professional Magnetic resonance imaging (MRI) for high-risk patients In mammography, low-dose x-rays of both breasts are taken in 2 views (oblique and craniocaudal). Mammography is more accurate in women over 50, partly because with aging, fibroglandular tissue in breasts tends to be replaced with fatty tissue, which can be more easily distinguished from abnormal tissue ( Screening references ). Mammography is less sensitive in women with dense breast tissue, and some states mandate informing patients that they have dense breast tissue when it is detected by screening mammography. Women with dense breast tissue may require additional imaging tests (eg, breast tomosynthesis [3-dimensional mammography], ultrasonography, MRI). Screening mammography guidelines for women with average risk of breast cancer vary, but generally, screening starts at age 40, 45, or 50 and is repeated every year or two until age 75 or life expectancy is < 10 years (see table). In May 2023, the United States Preventive Services Task Force (USPSTF) issued a draft update to recommendations, proposing that women start screening mammography at age 40 (the 2016 guidelines recommend starting at age 50) (seeUSPSTF Recommendation Summary). Clinicians should make sure that patients understand what their individual risk of breast cancer is and ask patients what their preference for testing is. TheBreast Cancer Risk Assessment Tool(BCRAT), or Gail model, can be used to calculate a woman's 5-year and lifetime risk of developing breast cancer based on a woman’s current age, age at menarche, age at first live childbirth, number of 1st-degree relatives with breast cancer, and results of prior breast biopsies. According to the Gail model, patients with higher than a 1.67% 5-year risk of breast cancer are high risk. Concerns about when and how often to do screening mammography include Rate of false-positive positive results Risks and costs Only about 10 to 15% of abnormalities detected on screening mammography result from cancer—an 85 to 90% false-positive rate. False-negative results may exceed 15% ( Screening references ). Many of the false-positives are caused by benign lesions (eg, cysts, fibroadenomas), but there are concerns about detecting lesions that meet histologic definitions of cancer but do not develop into invasive cancer during a patient's lifetime. (3-dimensional mammography), done with digital mammography, increases the rate of cancer detection slightly and decreases the rate of recall imaging ( Screening references ); this test is helpful for women with dense breast tissue. However, the test exposes women to 50 to 100% more radiation as traditional mammography. Although mammography uses low doses of radiation, Risks of Medical Radiation has cumulative effects on cancer risk ( 40 ( Screening references ). In the United States, CBE augments rather than replaces screening mammography. The American Cancer Society and the US Preventive Services Task Force recommend against screening with clinical breast examination (CBE); the American College of Obstetricians and Gynecologists recommends counseling patients about its diagnostic limitations ( Breast self-examination (BSE)alone as a screening methodhasnotshown a benefitand may result in higher rates of unnecessary breast biopsy. The major professional organizations do not recommend it as part of routine screening. However, women should be counseled about breast self-awareness, and if they notice changes in how their breasts appear or feel (eg, masses, thickening, enlargement), they should be encouraged to have a medical evaluation. MRI is used for screening women with a high (>20%) risk of breast cancer, such as those with aBRCAgene mutation. For these women, screening should include MRI as well as mammography and CBE. MRI has higher sensitivity but may be less specific. MRI may be recommended for women with dense breast tissue as part of overall assessment that includes evaluation of risk. 1.Practice bulletin no. 179: Summary: Breast Cancer Risk Assessment and Screening in Average-Risk Women.Obstet Gynecol130 (1), 241–243, 2017. doi:10.1097/AOG.0000000000002151 2.U.S. Preventive Services Task Force: Screening for breast cancer: U.S. Preventive Services Task Force recommendation statement.Ann Intern Med151 (10):716–726, W-236, 2009. doi:10.7326/0003 -4819-151-10-200911170-00008 3.Boyd NF, Guo H, Martin LJ, et al: Mammographic density and the risk and detection of breast cancer.N Engl J Med356(3):227-236, 2007. doi:10.1056/NEJMoa062790 4.Nelson HD, Fu R, Cantor A, et al: Effectiveness of breast cancer screening: Systematic review and meta-analysis to Update the 2009 U.S. Preventive Services Task Force Recommendation.Ann Intern Med164 (4):244–255, 2016. doi: 10.7326/M15-0969 5.Friedewald SM, Rafferty EA, Rose SL, et al: Breast cancer screening using tomosynthesis in combination with digital mammography.JAMA311 (24):2499–2507, 2014. doi: 10.1001/jama.2014.6095 6.Miglioretti DL, Lange J, van den Broek JJ, et al: Radiation-Induced Breast Cancer Incidence and Mortality From Digital Mammography Screening: A Modeling Study.Ann Intern Med164(4):205-214, 2016. doi:10.7326/M15-1241 