Interval between breast-conserving surgery and start of radiation therapy in early-stage breast cancer is not predictive of local recurrence: a single-institution experience

Abstract

Background: The aim of this study was to evaluate if the interval between breast-conserving surgery and the start of radiotherapy has an effect on local relapse risk.

Materials and methods: Between January 2000 and December 2006 a total of 387 patients with T1-2N0+ breast cancer were treated with breast-conserving surgery and radiotherapy, with and without hormone therapy and chemotherapy. Adjuvant radiotherapy was administered to a total dose of 60 to 66 Gy in 30 to 33 fractions. The time intervals between breast-conserving surgery and the start of radiotherapy were < 60, 61 to 120, 121 to 180 and > 180 days. The Kaplan-Meier method was used to calculate local relapse-free survival rates, and the Cox regression method was used to identify predictive factors of local relapse. Evaluated variables were age, tumor location, tumor histologic type, tumor size, surgical margin status, axillary node status, estrogen receptors, tumor grading, adjuvant therapy, adjuvant chemotherapy, radiation therapy, boost dose, and interval between breast-preserving surgery and start of radiation therapy.

Results: Five-year local relapse-free survival rates were 97.3% ± 1.5% for patients who did not receive chemotherapy and 94.5% ± 1.9% for patients who received chemotherapy (P = .71). There was no significant difference in local relapse among the 4 interval groups (P = .9). Multivariate Cox regression analysis showed that intervals between breast-conserving surgery and radiotherapy were not associated with higher local relapse risk.

Conclusion: In our study a delay in administering radiotherapy after breast-conserving surgery was not associated with an increased risk of local relapse. Taking into account contrasting results of many published studies, a larger evaluation of this issue is warranted.