Over-diagnosis estimated at 6.5 percent; cumulative risk of false-positive result is 20 percent
THURSDAY, Sept. 13 (HealthDay News) -- For women in Europe, mammographic screening is associated with a reduction in breast cancer mortality that is greater than the potential harms of over-diagnosis and false-positive screening results (FPRs), according to a study published in the September issue of the Journal of Medical Screening.
Eugenio Paci, M.D., from the Cancer Prevention and Research Unit in Florence, Italy, and colleagues reviewed European studies to examine the benefit and potential harms of mammography screening. Estimates of the reduction in breast cancer mortality were compared with over-diagnosis and FPRs.
The researchers found that, among invited women, the reduction in breast cancer mortality was 25 percent in incidence-based mortality studies and 31 percent in case-control studies (38 and 48 percent, respectively, among those who were actually screened). Over-diagnosis was estimated at between 1 and 10 percent of the expected incidence in the absence of screening, with a combined estimate from European studies of 6.5 percent, adjusted for lead time and underlying trend. For women undergoing 10 biennial screening tests, the estimated cumulative risk of a FPR followed by a non-invasive assessment was 17 percent; the estimated cumulative risk of a FPR followed by an invasive assessment was 3 percent.
"The estimated number of breast cancer deaths avoided by screening clearly exceeds the estimated number of cases of over-diagnosis," the authors write. "These results are intended to help a woman who is invited to screening to make an informed personal choice about the possible outcomes and the implications of participating in screening."
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