Radiation Treatment Increases Risk of Contralateral Breast Cancer Connected With Rare ATM Gene

A small portion of patients with breast cancer may carry a gene susceptible to radiation-induced damage that increases the risk of presenting with cancer in the contralateral breast, according to a research article in the April 7, 2010, Journal of the National Cancer Institute.

Out of 52,536 unilateral breast cancer survivors in the international Women’s Environmental, Cancer and Radiation Epidemiology Study, 708 presented with cancer in the contralateral breast. Jonine L. Bernstein, et al, screened for the entire ATM gene and estimated the radiation dose based on medical records and measurements from participants who underwent radiation therapy. The ataxia telangiectasia mutated (ATM) gene regulates cellular responses to the radiation-induced DNA damage, which is an established breast carcinogen, according to the study, “Radiation Exposure, the ATM Gene, and Contralateral Breast Cancer in the Women’s Environmental Cancer and Radiation Epidemiology Study.”

The authors found that among the less than 1 percent of study participants with a particular ATM missense variant, radiation exposure of 1 Gy or greater significantly increased the risk of breast cancer compared to the control group of 1,397 women and the women with the variant who were not exposed to radiation treatment.

“The increased risk of radiation-related contralateral breast cancer associated with specific ATM mutations may be an important factor in the selection of treatment for breast cancer for women who have a family history of ataxia-telangiectasia, a rare auto-somal recessive disorder that arises from inactivating mutations in the ATM gene,” the authors concluded.