How Common Is Overdiagnosis of Breast Cancer in the United States?

By: Vanessa A. Carter, BS
Posted: Monday, April 4, 2022

Marc D. Ryser, PhD, of Duke University Medical Center, Durham, North Carolina, and colleagues conducted a study to estimate the rate of breast cancer overdiagnosis via mammography to detect nonprogressive cancer. Published in the Annals of Internal Medicine, this analysis uncovered that among patients who are screened every 2 years, approximately one in seven cases of screen-directed cancer is overdiagnosed.

“We have known for a long time that the most prominent estimates of breast cancer overdiagnosis in the United States were unrealistically high,” stated Dr. Ryser in a video accompanying the study publication and featured in a Fred Hutchinson Cancer Research Center press release. “I hope that our overdiagnosis estimate of 15% among screen-detected cases will be adopted as a new standard and will lead to better-informed decision making around breast cancer screening, follow-up testing, and treatment.”

Overdiagnosis approximations were based on individual screening and diagnosis histories from 35,986 women between the ages of 50 and 74 who underwent one or more mammograms at a Breast Cancer Surveillance Consortium (BCSC) facility. Since overdiagnosis is not observable directly, it was estimated indirectly through Bayesian inference of the natural history of breast cancer.

This cohort included the data of 82,677 mammograms and 718 cases of breast cancer. The median age at first screen was 56 years, with a local peak at 65 years, which correlated with the starting age of Medicare eligibility. Each woman underwent 2.3 screens on average; approximately half of patients (51.3%) had a single exam, whereas the majority (92.1%) underwent up to five exams.

Approximately 4.5% of all preclinical cancer cases were estimated to be nonprogressive. In fact, 15.4% of screen-detected cancer cases were predicted to be overdiagnosed; 9.3% was due to detecting progressive preclinical cancer in women who may have died of an unrelated cause, and 6.1% was due to detecting indolent cancer. Notably, this rate rose from 11.5% at the first screen at age 50 to 23.6% at the last screen at age 74.

Disclosure: For full disclosures of the study authors, visit www.acpjournals.org.

Annals of Internal Medicine

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