Importance of timing of radiotherapy in breast conserving treatment for early stage breast cancer.

This study reports on the treatment results in 508 patients with 514 AJCC stage I-II invasive breast carcinomas treated between July 1980 and July 1989. All patients underwent a lumpectomy with axillary lymph node dissection with postoperative irradiation. Adjuvant chemotherapy was given to premenopausal node-positive patients. Postmenopausal node-positive patients received adjuvant hormonal treatment. The median follow-up period was 68 months (range, 40-152 months). The 5-year survival rates were 92.6%, 81.4% and 65.5% for stage I, stage IIA and stage IIB, respectively. Distant metastases were the main cause of death. Locoregional failures occurred in 4.9%. Breast recurrences were detected in 17 patients (3.3%). In a Cox proportional hazards analysis, T-stage, pathological margins and interval between surgery and radiotherapy were identified as independent factors predictive of breast recurrence (p < 0.05). The results suggest that radiotherapy should be initiated early after surgery to maintain the breast recurrence rate as low as possible.