Radiation therapy and breast cancer.

Although the role of radiation therapy in the management of ductal carcinoma in situ is somewhat controversial, the benefit of radiation therapy in breast-conserving treatment of early stage invasive breast cancer is well established. Patients undergoing tumor excision with clear margins have low rates of recurrence with radiation therapy whether there is an extensive intraductal component or not. In all patients, there is a significantly higher risk of recurrence without radiation therapy. In patients receiving systemic therapy, the optimal sequence of chemotherapy and radiation therapy is still being defined; however, in patients with positive nodes and negative margins it is now clear that it is preferable to start chemotherapy first.