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If you're a woman aged 40 or older, you may be aware that recommendations about when and how often to have a mammogram have changed over the years. The most recent recommendations come from the US Preventive Services Task Force (USPSTF), a well-respected panel of experts in prevention, evidence-based medicine, and primary care.
We all want to prevent breast cancer or find it in the earliest, most treatable stage. We'd like to think that mammograms can accomplish that — but mammograms are screening tests, and no screening test is perfect. Mammograms reveal signs of disease before you have any symptoms. But they might not detect disease in some women who have it, or might indicate disease in women who don't (false positive), leading to unnecessary further testing and treatment. Mammograms can also lead to overdiagnosis: finding and treating a condition that you and your clinician (doctor, nurse practitioner, nurse midwife, physician assistant) would not have known about without screening, and that would not have caused any health problems. Therefore we must weigh the benefits of the test (early cancer detection) against the possible harms (false positives and overdiagnosis). As good-quality research has progressed, the benefits and harms of mammograms have become clearer. This research shows that women who get screened regularly over a 10-year period are less likely to die of breast cancer.
The new guidance applies only to women of “average risk.” It is not for women who have a higher chance of developing breast cancer, including those with previous breast cancer or a biopsy-confirmed related condition (for example, atypical hyperplasia), a known genetic condition that raises risk (for example, BRCA1 or BRCA2 mutations), or a history of chest radiotherapy. Here is what the USPTSF recommends:
If you are 50 to 74, have a mammogram every 2 years.
If you are younger than 50, discuss with your clinician your preferences about having a screening mammogram. It's not clear whether women younger than 50 benefit much from mammograms, and breast cancer is less common in this age group. But your thoughts about screening are important and should be respected.
If you are 75 or older, it's also not clear whether mammograms provide a benefit. Discuss with your clinician your preferences as well as your overall health.
Breast tomosynthesis, also called 3-D mammography, is a newer specialized x-ray that takes images of the breasts from many angles and assembles them into a 3-dimensional picture. Current mammogram technology looks at the breast from only two angles. Researchers hope that tomosynthesis will detect developing cancers better than mammography. However, the USPTSF found that:
Research findings are not yet sufficient to determine the benefits and harms of adding tomosynthesis to “regular” mammograms.
Many women have “radiologically dense breasts.” Your breasts are made up of glandular tissue — the milk-producing lobules and the ducts that convey milk to the nipples — and fibrous and fatty tissue, which give the breasts their shape. If you have a lot of glandular and fibrous tissue and less fatty tissue, you may be told that your mammogram shows dense breasts. Having dense breast tissue is common, and carries a somewhat increased risk for breast cancer in the future. In addition, dense breast tissue may make early cancers more difficult for the radiologist (medical specialist who interprets the mammogram) to see. Further testing with ultrasound, magnetic resonance imaging (MRI), or tomosynthesis is sometimes recommended. However, the USPTSF found that:
Research findings are not yet sufficient to determine the benefits and harms of adding MRI or tomosynthesis to mammograms for women with dense breasts.
Although we'd like to think that mammograms are the solution to finding breast cancer early for all women, they are not perfect. The USPTSF recommendations as well as those of other professional organizations (such as the American Cancer Society) are based on the best research available. It's important to note that these and other recommendations can support a discussion between you and your clinician so you can make an informed choice about when and how often to have mammograms. Health insurance will probably continue to pay for mammograms, and all states have programs for uninsured women to obtain this screening test. The recommendations will likely change again in the future as tests and treatments evolve. In the meantime, don't forget that a healthy lifestyle (avoiding tobacco, eating a balanced diet, maintaining a healthy weight, not overusing alcohol) and breast-feeding lower your risk for many cancers and other health problems.
http://www.uspreventiveservicestaskforce.org
U.S. Preventive Services Task Force (Summary for Patients).Screening for breast cancer: Recommendations from the U.S. Preventive Services Task Force. Ann Intern Med 2016 Jan 12; [e-pub]. (http://dx.doi.org/10.7326/P16-9005)