(Ivanhoe Newswire) -- The risk for a new cancer in the unaffected breast substantially increases in women diagnosed with unilateral, hereditary breast cancer, according to a recent study.

The study, led by Katarina Shahedi, M.D., of the Umeå University and the Karolinska Institute in Stockholm, Sweden, reveals women younger than 50 diagnosed with hereditary (non-BRCA) breast cancer are at a significantly higher risk for developing cancer in the other breast, all known as contralateral breast cancer (CBC).

Researchers reviewed data from 120 families and 204 women with unilateral breast cancer and a family history of breast cancer but no BRCA mutations to better characterize the CBC risk for the women. They found the long-term CBC risk is significantly higher in women with hereditary breast cancer compared to the risk of developing a primary breast cancer in the general population.

Women taking adjuvant hormonal therapy, however, had a significantly lower risk for CBC compared to those not taking it. According to study authors, adjuvant chemotherapy had no apparent effect on risk.

Study authors say the impact of these results is most apparent for premenopausal women, as one in five will develop CBC after only 10 years. It is therefore important to consider and provide information about the risk of CBC to women with unilateral breast cancer or a family history of breast cancer.

SOURCE: CANCER, published online Feb. 13, 2006