Radiotherapy in the treatment of hereditary breast cancer.

Hereditary breast cancer represents approximately 5% to 10% of breast cancers and a larger portion of patients with early-onset disease. Given the relatively recent identification of the BRCA1 and BRCA2 genes, the available literature with respect to outcomes related to radiation therapy has inherent limitations with relatively small patient numbers and a lack of prospective randomized trials. There is, however, a growing body of literature describing treatment and toxicity outcomes in patients undergoing radiation therapy after breast-conserving surgery and after mastectomy for breast cancer patients who have BRCA1 and BRCA2 mutations. Acknowledging the limitations in the available data, there does not appear to be any evidence of more severe normal tissue reactions or compromised long-term survival rates in women electing breast-conserving surgery and radiation. These studies are reviewed in this article. Outcomes related to radiation therapy in patients with variants in other breast cancer-related genes, such as p53, ATM, CHEK2, PALB2, and PTEN, are even less well documented because of the paucity of data. Available reports on radiation-related outcomes in these and single nucleotide polymorphisms in radiation repair and response genes are discussed.