Radiation therapy and early breast cancer: current controversies.

Radiation therapy (RT) is an important component of breast cancer treatment. RT reduces local recurrence and breast cancer mortality after breast conservation for all patients and for node-positive patients after a mastectomy. Short courses of RT over 3-4 weeks are generally as effective as longer courses. A patient subgroup where RT can be avoided after conservative surgery has not been consistently identified. A radiation boost reduces the risk of a recurrence in the breast but may be omitted for older patients with good prognosis tumours with clear margins. Axillary recurrences can take a long time to appear, with 35% occurring after 5 years. Leaving disease untreated in regional nodes is associated with reduced survival. Not all patients require radiation after neoadjuvant chemotherapy and a subsequent mastectomy. Modern RT equipment and techniques will further improve survival rates.