Researchers report that women with a type of condition called atypical lobular hyperplasia, believed to be a precursor to breast cancer, are more likely to develop cancer in one breast than the other.

The Vanderbilt University researchers studied 252 women with the atypical lobular hyperplasia lesions, and 50 of them subsequently developed breast cancer. Almost 70 percent of cases occurred in the breast where the lesions were found.

The disease appeared in the opposite breast in only 24 percent of the cases, the researchers reported in the journal The Lancet.

Prior to this study, doctors believed that atypical lobular hyperplasia in one breast meant a much higher rate of breast cancer developing in either breast, often recommending a double mastectomy to prevent breast cancer down the line.

Dr. Sunil Lakhani of the Institute of Cancer Research and Royal Marsden Hospital in London, writing in the same issue, says the Vanderbilt study provides "evidence to counteract the myth that the risk of invasive carcinoma after a diagnosis of lobular in situ neoplasia is equal in both breasts."

"Invasive carcinoma after atypical lobular hyperplasia is about three times more likely to arise in the breast diagnosed with atypical lobular hyperplasia than in the opposite breast without these initial findings," the researchers concluded.

Other sources: The Lancet