Mammography takes another blow

In the latest of a series of articles questioning the value of annual mammograms for breast cancer screening, a meta-analysis of previously published studies estimates that mammography reduces the overall breast cancer rate by approximately 19% (and closer to 15% in women aged 40 to 50), with an equivalent percentage of over diagnosis in younger women.

Published on April 2 in the Journal of the American Medical Association, the article by Dr. Lydia Pace and Dr. Nancy Keating, two internal medicine physicians from Brigham and Women’s Hospital, was based on a literature review of 525 articles from 1960 to 2014 that described mammography’s benefits, harms and individualized screening decisions.

To describe the benefits of mammography, the authors focused on five meta-analyses published after 2006. To describe the harms (false positive results, unnecessary biopsies, overdiagnosis), the authors included 14 reviews published prior to 2008 and 72 reviews published after 2008. The authors found a cumulative false positive rate of 61% for women 40 or 50 years old undergoing 10 years of annual mammograms, and a 19% overdiagnosis rate.

Pace and Keating conclude that decisions on screening should be individualized based on patient’s risk profiles and preferences.

The reaction from the American College of Radiology was immediate, stating, “Breast cancer screening based primarily on risk — as discussed in the JAMA article — would miss the overwhelming majority of breast cancers present in women and result in thousands of unnecessary deaths each year.”

Calling into question the viability of including outdated or discredited studies, the college countered with data from the largest and longest-running randomized control trials, both of which found the benefit to be ~30% in women 50 and older, as well as women aged 40 to 50.

While the ACR agreed that women should discuss screening with their physician and that “breast cancer diagnosis and treatment may one day be more individualized”, it stands by its recommendation that women get annual mammograms beginning at age 40.

Nonetheless, the study was picked up by the consumer press, including the Wall Street Journal, which ran a summary of the study under the headline, “More Doubt on Mammogram’s Value.”  Although the article concludes with a quote in support of screening from Richard Wender, chief cancer control officer at the American Cancer Society, such coverage could deter some women from annual screening.

The study comes on the heels of the British Medical Journal’s publication of the results of the Canadian National Breast Screening study, which was widely criticized by the radiology community for including patients screened on obsolete 1980s-era technology and an overall trial design that lacked rigor.

For more information regarding the effectiveness of regular mammography screening, the ACR recommends visiting