Influence of the time between surgery and radiotherapy on local recurrence in patients with lymph node-positive, early-stage, invasive breast carcinoma undergoing breast-conserving surgery: results of the French Adjuvant Study Group.

BACKGROUND: Radiotherapy (RT) after breast-conserving surgery (BCS) has produced significant reductions in ipsilateral breast carcinoma (BC) recurrence. It was shown previously that a delay in the initiation of RT resulted in a higher local recurrence (LR) rate. In the current retrospective analysis, the authors investigated whether the RT-adjuvant therapy sequence modified local-disease-free survival (L-DFS) after BCS in patients with early-stage, lymph node-positive BC.
METHODS: Among 7 French Adjuvant Study Group trials, 1831 patients were assessable, including 475 patients who received RT directly after BCS (95 patients received no adjuvant therapy, and 380 patients received hormone therapy), 567 patients who received RT after the third chemotherapy (CT) cycle (250 patients received 1-3 courses, and 317 patients received 4-6 courses), and 789 patients received RT after the sixth CT cycle. In the 1356 patients who received CT, the regimens consisted of fluorouracil 500 mg/m(2); epirubicin 50 mg/m(2), 75 mg/m(2), or 100 mg/m(2); and cyclophosphamide 500 mg/m(2) in 83.5% of patients.
RESULTS: After a median follow-up of 102 months, 214 patients (11.7%) developed LR. The 9-year L-DFS rates were 92.0%, 81.5%, and 87.4%, respectively (P < 0.0001). It was worse in patients who received 1-3 CT cycles (P = 0.02). Patients who received hormone therapy were less likely to develop LR (P = 0.02). In the multivariate analysis, the timing of RT was not associated with a higher rate of LR, whereas tumor size > 2 cm and no hormone therapy were prognostic factors.
CONCLUSIONS: In the study population, there was no increase in the risk of LR when RT was delayed to deliver adjuvant CT. Prognostic factors were tumor size, and hormone therapy. The number of CT courses could modified this risk.