[Influence of the delay between conservative surgery and radiation therapy on local relapse in node-positive breast...

It has been shown that a delay in radiotherapy (RT) initiation resulted in a higher local relapse (LR) rate. The present analysis investigated retrospectively if the RT-adjuvant therapy sequence modified local-disease-free survival (L-DFS) after breast-conserving surgery (BCS) in node-positive (N +) breast cancer patients. Among seven French Adjuvant Study Group trials, 1,831 patients were assessable: 475 received RT directly after BCS, 567 after the 3rd chemotherapy (CT) cycle, and 789 after the 6th CT cycle. In the 1,356 patients receiving CT, it consisted of FEC regimens (fluorouracil, epirubicin, cyclophosphamide) in 83.5% of patients. After a 102-month median follow-up, 214 patients (11.7%) developed LR. The 9-year L-DFS rates were 92.0%, 81.5%, and 87.4%, respectively (p < 0.0001). In the multivariate analysis, the timing of RT was not associated with a higher rate of LR, whereas tumor size and hormonotherapy were prognostic factors. In our population, there was no increase in the risk of LR when RT was delayed to deliver adjuvant CT. Prognostic factors were tumor size, and hormonotherapy. The number of CT courses could modify this risk.