Superiority of breast-conserving surgery plus radiotherapy versus modified mastectomy in patients with stage I breast cancer: a propensity score-matching analysis

Objective: To compare the clinical efficacy between breast-conserving surgery (BCS) plus radiotherapy (RT) and modified mastectomy in patients with stage I breast cancer in clinical setting. Methods: Clinical data of 6137 patients diagnosed with pT_1-2N0 breast cancer from 1999 to 2014 were retrospectively reviewed. Among them, 1296 patients received BCS plus RT (BCS group) and 4841 cases underwent modified mastectomy alone (modified mastectomy group). Kaplan-Meier analysis was used for survival analysis. Log-rank test, single factor analysis and Cox's proportional hazards regression model were performed. The results were further confirmed with the propensity score-matching (PSM) method. Results: Within a median follow-up period of 55.2 months (range, 1-222 months), the 5- year locoregional recurrence-free survival (LRFS), distant metastasis-free survival (DMFS), disease-free survival (DFS) and overall survival (OS) were 96.3%, 93.7%, 91.9% and 96.9%, respectively. In the BCS plus RT group, the 5- year DMFS (96.9% vs. 92.9%, P < 0.001), DFS (94.9% vs. 91.2%, P = 0.005) and OS (99.1% vs. 96.4%, P = 0.001) were significantly higher than those in the mastectomy group. Multivariate analysis revealed that postoperative RT was an influencing factor of DMFS (P = 0.003, HR = 0.621; 95% CI: 0.455-0.849) and OS (P = 0.036; HR = 0.623; 95% CI: 0.401-0.969). For 1252 pairs of patients matched by PSM, the 5- year OS (99.1% vs. 96.1%, P = 0.001), DMFS (97.0% vs. 92.2%, P < 0.001) and DFS (95.3% vs. 90.2%, P = 0.001) in the BCS plus RT group were significantly higher compared with those in the mastectomy group. Conclusion: The long-term clinical prognosis of patients with stage I breast cancer in the BCS plus RT group is better than that in the mastectomy group. BCS plus RT should be recommended for patients with stage I breast cancer. (authors)