False-positive mammograms have long-term negative consequences

About half of American women receive a false-positive mammogram at some point in their lives. A false-positive mammogram happens when a women is told her initial mammogram is abnormal, but she later learns her breasts are healthy.

Photograph of Dr. Noel Brewer

“Women are scared by these abnormal tests, and their feelings of anxiety linger, sometimes for years,” said Noel T. Brewer, Ph.D., UNC assistant professor of health behavior and health education. “This kind of stress is unnecessary and unproductive to both their physical and mental well-being.”

To see how false-positives affect women, Brewer and two School of Public Health graduate students, Talya Salz and Sarah Lillie, combined data from more than 300,000 women in 28 research papers using a statistical procedure called meta-analysis. They found that women who received false positives were more anxious, worried and upset than women with normal results. The results were published in the April 2, 2007, issue of the Annals of Internal Medicine.

The research also revels that false-positive mammograms may increase some breast health behaviors. For instance, women who received false-positive mammograms were more likely to conduct breast self examinations. “We suspect that the increase in breast self exam is caused by feelings of anxiety that the false-positive mammograms cause,” said Brewer. “There is evidence that self-exams are not an effective way to find problems in the breasts.”

The study also showed unexpected difference between American and European women. When American women received a false-positive, it made them more likely to come back on time for their next mammogram. However, this effect was not found in European women.

The study’s findings have implications for health care policy. “U.S. women experience about 10 to 15 times as many false positives as European women, more than any other country in the world. This study should prompt policy makers to require mammograms to be more accurate,” Brewer said. “We also need to have the abnormal mammograms resolved as quickly as possible, because studies have shown that women who get their final results sooner are less anxious.”

The study’s results could also impact other medical tests. “Our previous research with Gulf War veterans found that false-positive chemical warfare alerts may be one cause for their unexplained medial symptoms,” Brewer said. “Medical testing is getting more sophisticated and more accessible. People regularly deal with genetic and genomic tests. You can even get a full body scan. All of these tests are subject to having false positives. As we increase the number of tests that people are exposed to, we run the risk of making them more and more anxious about their health.”

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Note: Brewer can be reached at 919-966-3282 or ntb1@unc.edu.

School of Public Health contact: Ramona DuBose, (919) 966-7467, ramona_dubose@unc.edu.

News Services contact: Becky Oskin, (919) 962-8596, becky_oskin@unc.edu.