Locoregional Radiation Therapy in Patients With High-Risk Breast Cancer Receiving Adjuvant Chemotherapy: 20-Year Results of the British Columbia Randomized Trial

The British Columbia randomized radiation trial was designed to determine the survival impact of locoregional radiation therapy in premenopausal patients with lymph node-positive breast cancer treated by modified radical mastectomy and adjuvant chemotherapy. Three hundred eighteen patients were assigned to receive no further therapy or radiation therapy (37.5 Gy in 16 fractions). Previous analysis at the 15-year follow-up showed that radiation therapy was associated with a statistically significant improvement in breast cancer survival but that improvement in overall survival was of only borderline statistical significance. We report the analysis of data from the 20-year follow-up.

Survival was analyzed by the Kaplan-Meier method. Relative risk estimates were calculated by the Wald test from the proportional hazards regression model. All statistical tests were two-sided.