Benefit and Risk of Mammography Screening – Considerations from an Epidemiological Viewpoint: Discussing the Benefit-Harm Debate

Abstract

Becker and Junkermann’s review article sheds light on a very important matter of health policy. Yet the problems begin as early as the title, which sets up a contrast between and risk rather than between and harm. The impression is conveyed that the of mammography screening stands against a (merely statistical) risk. This, of course, is not the case; both the benefit and the risk are statistical extrapolations of an expected and an expected harm. We consider the authors’ assessment of and harm to be imbalanced for a number of other reasons as well: The authors illustrate the of screening with a fictitious sample of 100 000 women who undergo screening every 2 years a total of 10 times. The harm, however, is illustrated with a fictitious group of only 1 000 women. For a group of 100 000 women in which screening would lead to the prevention of 540 deaths from breast cancer, the following types of harm would be expected to occur: 22 300 to 36 300 women would have false positive mammograms, 500 women would be overdiagnosed with breast cancer, 6300 women would have a false positive indication for a breast biopsy, about 500 women would go on to have a breast operation with a benign histological finding, and there would be 10 to 240 cases of radiation-induced breast cancer. Thus, every third woman undergoing screening every 2 years between the ages of 50 and 69 would be subjected to unnecessary worry, many women would undergo invasive diagnostic or therapeutic procedures on the basis of a false positive finding or an overdiagnosis, and a not inconsiderable number of breast cancers would actually be induced. There is no critical discussion of the quality of life of these unnecessarily disturbed women and their families; such a discussion is indispensable if the benefits and harms of screening are to be considered fairly. Thus, overall, the benefit-harm debate seems to lack balance.