Breast cancer and ATM mutations: treatment implications.

Genetic testing for breast cancer predisposing genes has expanded beyond BRCA1 and BRCA2 and now includes panels of 20 or more genes. It is now recommended that all women diagnosed with breast cancer at age 65 or below be offered testing for an extended gene panel. The rationale for testing includes personalizing the management of breast cancer according to the mutation found. For BRCA1 and BRCA2 carriers, the finding of a mutation has clear implications for cancer management, but for other genes, such as ATM, the management implications are less clear. Women with an ATM mutation have a lifetime risk of breast cancer of approximately 25%, the majority of which are ER-positive. The risk of ovarian cancer is approximately 5%. It is not yet clear how the identification of an ATM mutation in a patient newly diagnosed with breast cancer should impact on her treatment and follow-up. At present, these women are treated in the same way as women without a mutation. It is important that large prospective studies be conducted looking at various treatment modalities in women with breast cancer and an ATM mutation in order to optimize outcomes.