Screening is when tests or scans are used to detect conditions like breast cancer before, they cause any symptoms. Because breast cancer is the second leading cause of cancer death among women (after lung cancer) and because breast cancer is most treatable when diagnosed at its earliest stages, screening tools like mammography are used in women who are not having any symptoms to look for possible breast cancer.
Mammograms are the use of x-rays to take pictures of the breast tissue. During a mammogram, the breast is compressed between two plates to evenly spread out the tissue for a clearer image. Mammograms are an imperfect tool, as they may not find every breast cancer or may find lumps that turn out to not be cancerous, but they are currently the best screening tool available.
Several organizations have created screening recommendations regarding the use of mammography in women:
The American Cancer Society (ACS) recommends women with an average risk of breast cancer (such as those without a family history of breast cancer, those who have not previously had breast cancer, and those who have not previously had radiation to the chest) begin regular screening mammography at age 45 and yearly from age 45-54. At age 55, ACS recommends women have a screening mammogram every other year, with the option to continue having them yearly. As long as their overall health is good, and they have a life expectancy of 10 years or longer, women should continue getting screening mammograms. Women age 40-44 should also have the choice to begin yearly screening mammography if desired.1
The American College of Obstetricians and Gynecologists (ACOG) emphasize the shared decision-making that should occur between a woman and her healthcare professional. ACOG recommends that women of average risk of breast cancer should be offered screening mammography beginning at age 40. Women should have their first screening mammogram no later than age 50. Based on a discussion with their physician, women should continue screening mammography on a yearly or biennial (every other year) basis until at least 75 years of age. After age 75, the decision to continue screening mammography should be based on the individual woman’s health status and expected longevity, with a discussion with their doctor to help make a shared decision.2
The U.S. Preventive Services Task Force support that the decision to begin screening mammography in women before age 50 should be up to the individual. Women who decide that the potential benefit outweighs the potential harms may choose to have biennial (every other year) mammograms between 40 and 49 years of age. Between the ages of 50 and 74, women should have biennial screening mammograms. The evidence for the benefit of screening mammograms in women aged 75 and older is unclear.3
Risks of mammography
To understand the risks and benefits of screening for breast cancer, it is helpful to understand a few terms, such as:
False positive: When test results show something (such as a suspicious, possibly cancerous area on a mammogram) that is actually not concerning. False positives are like “false alarms,” which can cause additional testing (like biopsies) and significant emotional strain.
Overdiagnosis: When someone receives a diagnosis (and potentially subsequent treatment) for a condition that may never have developed into a serious condition or may not have caused any threat to the person’s life.
Overtreatment: When someone receives treatment (for a condition that may have resolved on its own or not caused symptoms) that can cause more harm than benefit, due to side effects, some of which can be long-term.
Mammograms can cause false positives, particularly in younger women or women with dense breast tissue. False positives require women to undergo additional testing, including ultrasound and biopsies. Because of this, the use of screening mammography in younger women can potentially lead to anxiety, overdiagnosis, and overtreatment.2
Clinical breast exam and breast self-exam
Clinical breast exam (where a healthcare professional conducts an inspection of the breasts by looking and feeling) and breast self-exam have not been found to be effective screening tools in finding breast cancers early and are generally no longer recommended as screening tools.4 While mammography remains the best screening tool to find breast cancers at their earliest stages, it is important for all women to know what’s normal for their breast tissue and bring any changes to the attention of their doctor.
Screening for women at high risk of breast cancer
Women who are at a high risk of breast cancer, due to family history of breast cancer or a known genetic mutation (like BRCA1 or BRCA2), may benefit from getting screening mammograms more frequently or beginning at an earlier age. In addition, women with a strong family history may want to consider genetic testing and discuss additional options for reducing their risk of breast cancer with their doctor.5 Patients should discuss their individual screening plan with their doctor to determine the risks/benefits of screening options and to ensure they have the best plan for them as an individual.
Oeffinger KC, Fontham ETH, Etzioni R, et al. Breast cancer screening for women at average risk: 2015 guideline update from the American Cancer Society. JAMA. 2015;314(15):1599-1614. doi:10.1001/jama.2015.12783
ACOG Revises Breast Cancer Screening Guidance: Ob-Gyns Promote Shared Decision Making. The American College of Obstetricians and Gynecologists. Available at https://www.acog.org/About-ACOG/News-Room/News-Releases/2017/ACOG-Revises-Breast-Cancer-Screening-Guidance--ObGyns-Promote-Shared-Decision-Making. Accessed 8/21/18.
Breast cancer screening guidelines for women. Centers for Disease Control and Prevention. Available at https://www.cdc.gov/cancer/breast/pdf/BreastCancerScreeningGuidelines.pdf. Accessed 8/21/18.
Kösters JP, Gøtzsche PC. Regular self-examination or clinical examination for early detection of breast cancer. Cochrane Database Syst Rev. 2003;(2):CD003373. doi: 10.1002/14651858.CD003373. https://pdfs.semanticscholar.org/5ac9/43e0db77e31f83f13e63a75d5e8429d11dc2.pdf.
Breast and ovarian cancer and family history risk categories. Centers for Disease Control and Prevention. Available at https://www.cdc.gov/genomics/resources/diseases/breast_ovarian_cancer/risk_categories.htm. Accessed 8/21/18.