15.4 Percent of Screen-Detected Breast Cancer Cases Are Overdiagnosed

TUESDAY, March 1, 2022 (HealthDay News) -- Among women undergoing biennial mammography screening from age 50 to 74 years, about 15.4 percent of screen-detected cases are estimated to be overdiagnosed, according to a study published online March 1 in the Annals of Internal Medicine.

Marc D. Ryser, Ph.D., from the Duke University Medical Center in Durham, North Carolina, and colleagues estimated the rate of breast cancer overdiagnosis in contemporary mammography practice, while taking into account the identification of nonprogressive cancer. The rate of overdiagnosis was predicted by a combination of a fitted natural history model with life-table data. Data were included for a cohort of 35,986 women who were aged 50 to 74 years at first mammography between 2000 and 2018, with 82,677 mammograms and 718 breast cancer diagnoses.

The researchers found that 4.5 percent of all preclinical cancer cases were estimated to be nonprogressive. Overall, 15.4 percent of screen-detected cancer cases were estimated to be overdiagnosed in a program of biennial screening from age 50 to 74 years, with 6.1 and 9.3 percent due to detecting indolent preclinical cancer and progressive preclinical cancer in women who would have died of an unrelated cause before clinical diagnosis, respectively.

"We find that the rate of overdiagnosis in U.S. population-based mammography screening is unlikely to be as high as suggested by prominent excess-incidence studies," the authors write. "We hope that our findings will bring the field closer to a consensus estimate and facilitate decision making about mammography screening."

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