Breast cancer screening is recommended for all women in the United States, but major medical organizations vary regarding the starting age and frequency of screening (see table Recommendations for Breast Cancer Screening Mammography in Women With Average Risk) (1, 2). Determining screening recommendations involves evaluation of benefits and harms regarding screening efficacy in decreasing breast cancer mortality and the false-positive rate. The mainstay of breast cancer screening is mammography; clinical breast examination is also used for screening, and MRI is used for certain high-risk patients.
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
Mammography
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 (3). 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 Recommendations for Breast Cancer Screening Mammography in Women With Average Risk). 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) (see USPSTF 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.
The Breast 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% (4). 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.
Breast tomosynthesis (3-dimensional mammography), done with digital mammography, increases the rate of cancer detection slightly and decreases the rate of recall imaging (5); 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, radiation exposure has cumulative effects on cancer risk (6).
Breast examination
Clinical breast examination (CBE) is usually part of routine annual care for women > 40 (1). 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 (1, 2). However, in some countries where mammography is considered too expensive, CBE is the sole screen; reports on its effectiveness in this role vary.
Breast self-examination (BSE) alone as a screening method has not shown a benefit and 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
MRI is used for screening women with a high (> 20%) risk of breast cancer, such as those with a BRCA gene 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.
Screening references
1. Practice bulletin no. 179: Summary: Breast Cancer Risk Assessment and Screening in Average-Risk Women.Obstet Gynecol 130 (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 Med 151 (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 Med 356(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 Med 164 (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. JAMA 311 (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 Med 164(4):205-214, 2016. doi:10.7326/M15-1241
Prevention of Breast Cancer
Measures for breast cancer prevention include
Lifestyle modifications
Surgery
Chemoprevention
Some studies have found that eating a healthy diet, maintaining a healthy weight, exercising regularly, and limiting alcohol intake are associated with a decreased risk of breast cancer (1). In addition, patients should be counseled about avoiding modifiable factors that increase risk of breast cancer (eg, combination estrogen-progestogen menopausal hormone therapy).
Certain high-risk populations (BRCA mutation carriers) may benefit from risk-reducing mastectomy.
Previous lobular carcinoma in situ (LCIS) or atypical ductal or lobular hyperplasia
A 5-year risk of developing breast cancer > 1.67%, based on the Gail model
History of thoracic radiation received at < 30 years old
Presence of high-risk mutations (eg, BRCA1 or BRCA2 mutations, Li-Fraumeni syndrome)
A computer program to calculate breast cancer risk by the Gail model is available from the National Cancer Institute (NCI) at 1-800-4CANCER and on the NCI web site. Recommendations of the U.S. Preventive Services Task Force (USPSTF) for chemoprevention of breast cancer are available from the USPSTF and the American Society of Clinical Oncology.
23, 4). Chemoprevention is indicated for any individual patient only if the benefit outweighs the risk of adverse effects.
Risks of include
Thromboembolic complications
Cataracts
Possibly stroke
Risks are higher for older women.
Raloxifene, like tamoxifen, may also increase bone density. Raloxifene should be considered as an alternative to tamoxifen for chemoprevention in postmenopausal women.
Osteoporosis is a risk of aromatase inhibitor therapy.
Prevention references
1. Malcomson FC, Wiggins C, Parra-Soto S, et al: Adherence to the 2018 World Cancer Research Fund (WCRF)/American Institute for Cancer Research (AICR) Cancer Prevention Recommendations and cancer risk: A systematic review and meta-analysis [published online ahead of print, 2023 Jun 13]. Cancer 10.1002/cncr.34842, 2023. doi:10.1002/cncr.34842
2. Cuzick J, Forbes JF, Sestak I, et alJ Natl Cancer Inst 99(4):272-282, 2007. doi:10.1093/jnci/djk049
3. Nelson HD, Fu R, Zakher B, et al: Medication Use for the Risk Reduction of Primary Breast Cancer in Women: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. JAMA 322(9):868-886, 2019. doi:10.1001/jama.2019.5780
4. Vogel VG, Costantino JP, Wickerham DL, et alCancer Prev Res (Phila) 3(6):696-706, 2010. doi:10.1158/1940-6207.CAPR-10-0076
Key Points
Screen women by doing clinical breast examination, mammography (beginning at age 50 and often at age 40), and, for women at high risk, MRI.
More Information
The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
U. S. Preventive Services Task Force: Breast Cancer: Medication Use to Reduce Risk: This web site provides the rationale of using medications to reduce the risk of breast cancer in women at high risk and describes the risks of using these medications.
National Cancer Institute: Breast Cancer: This web site discusses the genetics of breast and gynecologic cancers and the screening for and prevention and treatment of breast cancer. It also includes evidence-based information about supportive and palliative care.
