Breast Cancer, JAMA, Outcomes & Safety / 03.04.2014
Mammography: Risks of False Positive Results and Overdiagnosis
MedicalResearch.com Interview with:
Dr. Lydia Pace, MD, MPH
Division of Women’s Health, Brigham and Women’s Hospital
Boston, Massachusetts
MedicalResearch.com: What are the main findings of the study?
Dr. Pace: We reviewed the existing literature about the benefits and harms of mammography, focusing on the reduction of breast cancer deaths associated with mammography, as well as the two most often-discussed harms: false positive results and overdiagnosis. We also reviewed the literature about interventions to help patients make informed decisions. We found that the literature suggests that routine screening mammography does reduce mortality associated with breast cancer, across all age groups. However, it is also associated with high rates of false positive results, and considerable rates of overdiagnosis. Overdiagnosis is the most concerning potential risk of mammography screening. Overdiagnosis is the detection of a tumor through screening that would never have caused problems for a patient. It occurs either because of a very slow-growing tumor, or because a woman has medical problems (or is old enough) such that she will likely die of another cause before the cancer became apparent. Overdiagnosis is concerning because we cannot know when a cancer is overdiagnosed, and thus a patient who is overdiagnosed will receive unnecessary treatment for cancer. The scientific literature on mammography is complex, and there are important limitations to the studies both of mammography’s benefits and harms. However, we feel that the best available data suggest that among 10,000 50 year old women undergoing annual mammography for 10 years, 5 deaths will be averted through screening mammography, while about 6130 women will experience at least one positive result. Furthermore, there is about a 19% chance that, if that woman is diagnosed with cancer detected by a mammogram, that cancer is one that would never have caused her problems. Lastly, our review showed that we need more studies to guide us in how an individual woman’s risk should dictate her mammography decisions, and how to support women in making those decisions. However, we know that most women with higher risk for breast cancer will experience higher benefit from mammography screening.
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