Overview of randomized trials of postoperative adjuvant radiotherapy in breast cancer.

An overview of the mortality results of the mature trials in which radiotherapy was a randomized option after simple or radical mastectomy is presented. The principal aim of the overview was to study long-term survival, and recent trials, often including chemotherapy options, have not been included. A total of 7941 patients were entered into these trials and 4148 deaths occurred. No differences were found in survival in the first 10 years of follow-up, in trials employing either radical mastectomy or simple mastectomy. Follow-up information after 10 years came mostly from trials employing radical mastectomy with or without irradiation, and in these trials a significant excess of deaths was observed among patients given radiotherapy (P less than 0.001, all trials; P = 0.002, radical mastectomy trials only). Further data collection will be necessary to determine which causes of death are elevated.