Story highlights Women who have a false positive mammogram have a slightly higher risk of developing breast cancer

The findings suggest that a false positive result could be a moderate risk factor for breast cancer

Experts recommend women with histories of a false positive result be vigilant about regular mammograms

(CNN) Women who have a false positive result on their mammogram may actually be at slightly higher risk of developing breast cancer over the following decade, according to a new study.

Researchers looked at more than 2 million mammograms that had been performed on women ages 40 to 74 at health clinics across the United States between 1994 and 2009.

About 180,000 of the mammograms were false positives, meaning that the test detected a tissue abnormality but an additional imaging or biopsy test did not support a cancer diagnosis and the women did not develop breast cancer in the year after the mammogram. The remaining tests were true negatives because they did not detect an abnormality and were not associated with the development of breast cancer in the following year.

The researchers found that an additional one woman out of 100 who had a false positive mammogram and followed it up with another imaging test went on to develop breast cancer in the next decade, as compared with women who did not have a false positive result. Among women who had a false positive followed by a biopsy, an additional two out of 100 developed breast cancer. The larger increase in risk in the biopsy group was presumably because these women had tissue that was more abnormal and thus concerning enough for the radiologist to order the more invasive follow-up test.

"Given what we found, I would say that having a false positive (result) definitely does increase your risk for developing breast cancer," said Louise M. Henderson, an assistant professor of radiology at the University of North Carolina School of Medicine in Chapel Hill. Henderson is lead author of the study, which was published on Wednesday in the journal, Cancer Epidemiology, Biomarkers & Prevention.

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