Purpose: To analyze the relationship between a delay in radiotherapy (RT) after breast-conserving surgery and ipsilateral breast recurrence (BR).
Methods and materials: We included in our analysis 4,820 breast cancer patients who had undergone postoperative RT at the University of Florence. The patients were categorized into four groups according to the interval between surgery and RT (T1, <60 days; T2, 61-120 days; T3, 121-180 days; and T4, >180 days).
Results: On multivariate analysis, the timing of RT did not reach statistical significance in patients who received only postoperative RT (n = 1,935) or RT and hormonal therapy (HT) (n = 1,684) or RT, chemotherapy (CHT), and HT (n = 529). In the postoperative RT-only group, age at presentation, surgical margin status, and a boost to the tumor bed were independent prognostic factors for BR. In the RT plus HT group, age at presentation and boost emerged as independent prognostic factors for BR (p = 0.006 and p = 0.049, respectively). Finally, in the RT, CHT, and HT group, only multifocality was an independent BR predictor (p = 0.01). Only in the group of patients treated with RT and CHT (n = 672) did multivariate analysis with stepwise selection show RT timing as an independent prognostic factor (hazard ratio, 1.59; 95% confidence interval, 1.01-2.52; p = 0.045). Analyzing this group of patients, we found that most patients included had worse prognostic factors and had received CHT consisting of cyclophosphamide, methotrexate, and 5-fluorouracil before undergoing RT.
Conclusion: The results of our study have shown that the timing of RT itself does not affect local recurrence, which is mainly related to prognostic factors. Thus, the "waiting list" should be thought of as a "programming list," with patients scheduled for RT according to their prognostic factors.