Study suggests benefits of mammograms often overestimated, harms underestimated

Mammography screening is associated with reduced breast cancer mortality, but the benefit is modest and overdiagnosis can also cause harm by unnecessary treatment for tumors that would cause no harm.
By Alex Cukan   |   Updated April 3, 2014 at 5:25 PM
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BOSTON, April 2 (UPI) -- A review of international studies from 1960 to 2014 for the evidence on the mortality benefit and chief harms of mammography screening found women often are not aware of the harms associated with mammograms.

Review co-authors Nancy Keating, of the Harvard Medical School and Brigham and Women’s Hospital, and Lydia Pace of Women’s Health at Brigham and Women’s Hospital, said: "in 2009, the U.S. Preventive Services Task Force reversed its previous recommendation of having women beginning at age 40 getting a mammogram every one to two years. Instead, it recommended routine screening every two years beginning at age 50." However, recent research found few changes have occurred since the change in recommendation.

The review reported mammography screening was associated with a 19 percent overall reduction of breast cancer mortality -- approximately 15 percent for women in their 40s and 32 percent for women in their 60s.

Still, how much a woman benefits depends on her underlying risk of breast cancer and her preferences. Keating said the chief harm associated with mammography is the risk of overdiagnosis -- the detection of a tumor through screening that would not have caused harm if gone undetected. Overdiagnosis can occur either because of a tumor’s features, other mortality risks due to age or other diseases.

Using current medical procedures and tests it is impossible to know which cancers could be safely observed and which need to be treated and more research is needed to further pinpoint a diagnosis. Those overdiagnosed with breast cancer might receive unnecessary surgery, chemotherapy or radiotherapy.

“While we need more research on mammography’s benefits and harms today, existing data suggest that we have been overestimating the benefits of mammography and underestimating the harms over the years,” Pace said. “It is really important to have informed discussions with our patients to help them understand the chances that a mammogram will benefit them as well as the possible downsides of getting a mammogram, so that they can incorporate their own values and preferences in making the right decision for themselves.”

The findings were published Wednesday in the Journal of the American Medical Association.

[Journal of the American Medical Association]

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