False-Positive Mammogram and Breast Cancer Risk

False-Positive Mammogram and Breast Cancer Risk But researcher stresses that risk is small, and women should be vigilant with screenings
WebMD News from HealthDay

By Kathleen Doheny

HealthDay Reporter

WEDNESDAY, Dec. 2, 2015 (HealthDay News) -- In a finding that suggests a false-positive result on a mammogram may be somewhat more worrisome than thought, a new study says women who get such a result may be at increased risk of developing breast cancer later.

However, the study finding needs to be put into perspective, said study leader Louise Henderson, an assistant professor of radiology at the University of North Carolina at Chapel Hill.

"There are a lot of things that increase risk," Henderson said. A false positive "does increase your risk, but it is not increasing your risk to a huge degree. It's another piece to the puzzle of breast cancer risk."

In the study, published in the December issue of Cancer Epidemiology, Biomarkers & Prevention, the researchers analyzed national breast cancer data from 1994 through 2009. They looked at the results of more than 2.2 million screening mammograms done on nearly 1.3 million women in different parts of the United States. The women were aged 40 to 74.

After an initial screening, the researchers tracked the women for up to 10 years, looking to see if a false positive was linked with breast cancer risk later.

The women were divided into three groups: Those who had a negative result; those who had a false positive and were referred for additional tests (such as an MRI); and those who had a false-positive result and were sent for a biopsy. The researchers reasoned that those sent for a biopsy had more concerning or suspicious findings than those sent for additional testing.

Compared to women with a negative result, those who got a false positive and were referred for more tests had a 39 percent higher risk of developing cancer during the follow-up period. Women referred for a biopsy had a 76 percent higher risk of developing breast cancer than the women with a negative result did, the findings showed.

While those increased risks sound high, they need to be put into perspective, Henderson said. For women who got a false positive and were sent for more imaging, compared to those who got a negative result, about one or two additional women would develop breast cancer in the next decade, she said. In addition, for a false positive that led to a biopsy, an additional one to three women would develop breast cancer later.

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