The group said taking into account the Cochrane Review estimates, that these QALYs were slightly negative for the first seven years; after 10 years, they were positive again, with 70 QALYs gained, and after 20 years, 834 QALYs.

Adjusting for harms


Of course, it's hard to see how "adjusting" for mammography's harms can be done without a great deal of subjectivity. The researchers acknowledged some limitations in their method. They said their estimate for the personal toll of surgery -- a forever 6 percent loss in quality of life -- was a rather low-ball figure, drawn from the few studies available that looked into the matter. A 2010 review cited by the authors, based on two earlier studies, found the quality loss of between 8 and 38 percent after the first year of surgery.

"Overall, our assumption of a permanent 6 percent loss in quality of life from surgery does not seem unreasonable, but more robust estimates are needed," the authors said.

Quality of life lost from false positive results -- generally held to be caused by worry and anxiety over several months -- was deemed at 5 percent for just one-fifth of a year.

Still, the researchers said they weren't able to take into account the costs or benefits of different kinds of surgeries (lumpectomies versus mastectomies) or different treatments, such as chemotherapy or radiotherapy.

"More research is required on the extent of unnecessary treatment and its impact on quality of life," they said. "As randomized trials might be the only way to resolve the extent of overtreatment, researchers in countries that have not yet implemented breast cancer screening should consider trials that include the harms of screening."

Criticisms

In a statement, the American College of Radiology took the report to task for underestimating the life-saving benefits of screening.

“The estimated 15 percent reduction in breast cancer deaths used in this study is the same used in 2009 by the U.S. Preventative Services Task Force. That estimate has been discredited by a series of large randomized control trials and other data that prove the benefit is at least twice that,” Dr. Barbara Monsees, chair of the ACR's Breast Imaging Commission, said in a statement.

ACR cited recent studies in Radiology and Cancer that found screening would reduce breast cancer mortality by between 20 to 30 percent. It also mentioned an article that appeared in Cancer Epidemiology, Biomarkers & Prevention last week that said screening could cut the risk of dying from breast cancer in half.

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