Effect of Radiotherapy after Breast-Conserving Surgery on 10-Year Recurrence and 15-Year Breast Cancer Death: Meta-Analysis of Individual Patient Data for 10,801 Women in 17 Randomised Trials

Breast-conserving surgery (BCS) is traditionally followed by radiotherapy to the breast because of historic trials, such as the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-06, 1 which demonstrated that BCS is safe if combined with radiotherapy. The beneficial effect of radiotherapy was mainly felt to be reduction in rates of locoregional disease only. After BCS, radiotherapy reduces recurrence and breast cancer death, but it may do so more for some groups of women than for others. This paper describes the absolute magnitude of these reductions according to various prognostic and other patient characteristics, and relates the absolute reduction in 15-year risk of breast cancer death to the absolute reduction in 10-year recurrence risk.