Time Interval From Breast-Conserving Surgery to Breast Irradiation in Early Stage Node-Negative Breast Cancer: 17-Year Follow-Up Results and Patterns of Recurrence

Purpose A retrospectivechart review was conducted to determine whether the time interval from breast-conserving surgery to breast irradiation (surgery-radiation therapy interval) in early stage node-negative breast cancer had any detrimental effects on recurrence rates. Methods and Materials There were 566 patients with T1 to T3, N0 breast cancer treated with breast-conserving surgery and breast irradiation and without adjuvant systemic treatment between 1985 and 1992. The surgery-to-radiation therapy intervals used for analysis were 0 to 8 weeks (201 patients), >8 to 12 weeks (233 patients), >12 to 16 weeks (91 patients), and >16 weeks (41 patients). Kaplan-Meier estimates of time to local recurrence, disease-free survival, distant disease-free survival, cause-specific survival, and overall survival rates were calculated. Results Median follow-up was 17.4 years. Patients in all 4 time intervals were similar in terms of characteristics and pathologic features. There were no statistically significant differences among the 4 time groups in local recurrence ( P =.67) or disease-free survival ( P =.82). The local recurrence rates at 5, 10, and 15 years were 4.9%, 11.5%, and 15.0%, respectively. The distant disease relapse rates at 5, 10, and 15 years were 10.6%, 15.4%, and 18.5%, respectively. The disease-free failure rates at 5, 10, and 15 years were 20%, 32.3%, and 39.8%, respectively. Cause-specific survival rates at 5, 10, and 15 years were 92%, 84.6%, and 79.8%, respectively. The overall survival rates at 5, 10, and 15 years were 89.3%, 79.2%, and 66.9%, respectively. Conclusions Surgery-radiation therapy intervals up to 16 weeks from breast-conserving surgery are not associated with any increased risk of recurrence in early stage node-negative breast cancer. There is a steady local recurrence rate of 1% per year with adjuvant radiation alone.