Is “overdiagnosis” of breast cancer common among women screened by mammography?
Yes. This analysis of Surveillance, Epidemiology, and End Results (SEER) data from a 30-year span indicates that nearly one-third of all breast malignancies identified during screening are overdiagnosed—that is, they are unlikely ever to lead to clinical symptoms.
Bleyer A, Welch HG. Effect of three decades of screening mammography on breast-cancer incidence. N Engl J Med. 2012;367(21):1998–2005.
Andrew M. Kaunitz, MD
Professor and Associate Chairman, Department of Obstetrics and Gynecology, University of Florida College of Medicine–Jacksonville. Dr. Kaunitz serves on the OBG Management Board of Editors.
To reduce deaths from cancer, screening should achieve two goals:
It should lead to earlier detection of tumors likely to be fatal
It should lead to better outcomes after treatment of these tumors.
In other words, effective screening increases the incidence of cancers identified at an early stage (when they have a better prognosis) as it reduces the incidence of malignancies detected at a late stage.