About 1 in 7 breast cancer cases are overdiagnosed, a study published March 1 in the Annals of Internal Medicine found.
A breast cancer overdiagnosis occurs when a tumor is detected that would not have caused symptoms or signs in the remaining lifetime had it remained hidden.
Duke researchers analyzed 82,677 mammograms from 35,986 women ages 50 to 74 between 2000 and 2018. Among all preclinical cancer cases, 4.5 percent were estimated to be nonprogressive. Researchers found 15.4 percent of detected cases were estimated to be overdiagnosed, with 6.1 percent due to detecting indolent preclinical cancer and 9.3 percent due to detecting progressive preclinical cancer in patients who would have died of an unrelated cause before clinical diagnosis.