Link to article - NPR Interview included in link

Excerpt:

"We wanted to look at whether breast screening led to fewer advanced-stage cancers because screening is really based on the premise that you detect cancer earlier so you should have less advanced cancers over time," Jorgensen says.

But the analysis found that there was no "reduction in the frequency of late-stage tumors in the screened areas compared to the non-screened areas," Jorgensen says. "But we did see a huge increase in the occurrence of early-stage cancers."

The findings suggest mammograms are frequently picking up lumps that would never become a health problem. Like many prostate cancers, they may never grow or may even regress on their own.

"That means that these essentially healthy women get a breast cancer diagnosis that they otherwise would never have gotten," says Jorgensen. "It's really a life-changing event to get a cancer diagnosis."

Excerpt from the scientific paper:

Breast Cancer Screening in Denmark: A Cohort Study of Tumor Size and Overdiagnosis

What are the implications of the study?

Screening mammography does not seem to have delivered its promised benefit of earlier diagnosis. For many women, screening mammography may lead to a diagnosis of breast cancer based on tumors that would never have been noticed or become harmful during their lifetime. These women are unnecessarily treated with therapies, including surgery, radiation, and chemotherapy, that have adverse effects. Women and policymakers need to be aware of the shortcomings of screening mammography.

Author, Article, and Disclosure Information

This article was published at www.annals.org on 10 January 2017.

The full report is titled “Breast Cancer Screening in Denmark: A Cohort Study of Tumor Size and Overdiagnosis.” The authors are K.J. Jørgensen, P.C. Gøtzsche, M. Kalager, and P. Zahl.