Radiologists can rule out immediate biopsy for women with "probably benign" breast lesions and instead recommend a six-month follow-up diagnostic mammogram, says a new study.

The study from the Group Health Center for Health Studies, authored by Erin J. Aiello Bowles, MPH, has found that six-month short-interval follow-up examinations had 83 percent sensitivity, which is similar to the sensitivity of other diagnostic mammograms.

High sensitivity implies identifying a high proportion of "true positives" (actual cancer cases) and a low proportion of "false negatives" (cases mistakenly deemed benign).

The study involved 45,007 initial short-interval follow-up mammograms.

"Short-interval follow-up mammograms are done to monitor for changes in 'probably benign' breast lesions (findings seen on mammograms that have a very low probability of being cancer). Because the probability of cancer is so low, we don't want to put the patient through an unnecessary biopsy, which is an invasive procedure that increases both patient anxiety and medical costs," said Aiello Bowles.

"At the same time, we want to closely monitor these patients, because changes in 'probably benign' lesions occasionally mean cancer, and we want to detect the cancers as early as possible," she said.

Aiello Bowles said that during the study, the researchers diagnosed breast cancer in 360 women with "probably benign" lesions within six months; and 506 women were diagnosed with cancer within 12 months (altogether about one in 100 of the "probably benign" lesions).

"The Breast Imaging-Reporting and Data System (BI-RADS) recommends that women with a BI-RADS category 3 (probably benign) lesion get a six-month diagnostic mammogram, with follow-up continued for the next two to three years until long-term stability is demonstrated. This study emphasizes that radiologists and patients need to follow that recommendation," said Dr. Edward Sickles, a coauthor and radiologist involved in the study from the University of California San Francisco.