Adjuvant Radiation after Modified Radical Mastectomy for Breast Cancer Fails to Prolong Survival

Abstract

Recent literature has reported improved local disease control and overall survival in premenopausal node-positive (stage II, and HI) breast cancer patients undergoing modified radical mastectomy (MRM) using radiation therapy (RT) combined with chemotherapy. To assess the efficacy of postoperative RT in our own community, we analyzed all patients undergoing MRM for carcinoma utilizing an extensive database from the three major teaching hospitals in Tulsa, OK, between 1965 and 1993. A total of 5257 patients underwent MRM during this time period. One hundred thirty-seven patients were excluded for insufficient data or because they were found to be at stage IV, leaving a total study population of 5125. Overall survival (OS), overall mean survival (MS), disease-free survival (DFS), and locoregional DFS (LRDFS) were analyzed for all patients and were further analyzed according to stage, lymph node involvement, and menopausal status. Median follow-up was 103 months. Statistical analysis was performed using Kaplan-Meier and t-tests. The DFS at 10 years was 65 per cent in the RT group and 80 per cent in the patients who did not receive RT (P = 0.00). No improved DFS was obtained in the radiation-treated patients, regardless of stage, lymph node involvement, or menopausal status. Similarly, the LRDFS at 10 years was 91 per cent in the RT group and 96 per cent in the patients who did not receive RT (P = 0.00). No improved LRDFS was obtained in the radiation-treated patients, regardless of stage, lymph node involvement, or menopausal status. The overall MS was 97 months in the RT group and 104 months in the patients who did not receive RT (P = 0.00). Comparisons of overall MS rates revealed apparent survival benefits from RT in the premenopausal node-negative group, postmenopausal one to four-positive-node group, and all stage I patients. This apparent survival advantage was not confirmed by Kaplan-Meier curves of OS. No other overall MS differences were detected according to stage, lymph node, or menopausal status. Using Kaplan-Meier survival curves, the OS in the RT group at 10 years was 46 per cent, and 63 per cent in the patients who did not receive RT (P = 0.00). No improved OS was obtained in the radiation-treated patients, regardless of stage, lymph node involvement, or menopausal status. These findings from a large breast cancer database failed to demonstrate any meaningful benefit from RT after MRM and serve to further question the efficacy of this treatment modality in postmastectomy breast cancer patients.