Overdiagnosis of Noninvasive Tumors Followed Organized Breast Cancer Screening

By Kelly Young

Edited by David G. Fairchild, MD, MPH, and Jaye Elizabeth Hefner, MD

Seventeen years of organized breast cancer screening in Denmark has not reduced the incidence of advanced cancers — but has led to increased detection of noninvasive tumors and ductal carcinoma in situ (DCIS) — according to a study in the Annals of Internal Medicine.

Using cancer registries, researchers identified roughly 200,000 women aged 35 to 85 diagnosed with breast cancer from 1980 to 2010. Cancer detection rates were compared in screening and nonscreening areas. (Screening was introduced into different regions of the country at different times.)

Screening was not associated with a decrease in advanced tumors. The authors estimate that one out of every three invasive tumors and DCIS cases diagnosed after screening were overdiagnoses.

An editorialist writes, "We must carefully examine screening, realize its limitations, maximize its effectiveness, and try to improve it. In addition, we must examine all elements of breast cancer control (to include prevention) and evaluate how they are best used."