Reply to: Loss of QALY in mammography screening reported by Zahl et al.

摘要

In their letter, Njor and Lynge argue that mammography screening leads to 5% overdiagnosis and 20% reduction in breast cancer mortality and assume that all translates to reduced overall mortality. Njor et al. base their estimates on their own studies only,1 and ignore other more comprehensive studies from Denmark.Njor et al. included only 8% (57,763) of the available female Danish population when studying overdiagnosis.1 A later study including the complete Danish female population could not reproduce their estimate and reported 48% overdiagnosis.3 Their other study reporting 20% reduction in breast cancer mortality only included data from Copenhagen. In another study including all women invited to screening in the 1990s (twice as many), no effect of mammography screening on breast cancer mortality was seen.4