LAUSR

Background To investigate the superiority of breast‐conserving surgery (BCS) plus radiotherapy (RT) compared with mastectomy alone for patients with stage I breast cancer in a real‐world setting. Patients and Methods The data from patients with histologically confirmed stage I breast cancer treated from 1999 to 2014 were retrospectively reviewed. The association of outcomes with the choice of treatment (BCS plus RT vs. mastectomy) was evaluated using multivariable proportional hazards regression and further confirmed using propensity score matching methods. Results Of 6137 eligible patients in the present study, 1296 underwent BCS plus RT and 4841 underwent mastectomy plus axillary lymph node dissection without RT (mastectomy group). Multivariate analysis revealed that BCS plus RT was related to similar locoregional recurrence‐free survival but greater distant metastasis‐free survival (P = .003) and overall survival (P = .036) compared with mastectomy. For the 1252 pairs of patients matched using propensity score matching, the BCS plus RT groups enjoyed significantly greater 5‐year overall survival (99.1% vs. 96.1%; P = .001), distant metastasis‐free survival (97.0% vs. 92.2%; P < .001), and disease‐free survival (95.3% vs. 90.2%; P = .001) compared with the mastectomy group. Conclusion BCS plus RT provided better outcomes than mastectomy for eligible patients with stage I breast cancer and should be offered as a preferred treatment option. Micro‐Abstract In the present study, we retrospectively compared the outcomes of breast‐conserving surgery (BCS) plus radiotherapy (RT) versus mastectomy for stage I breast cancer patients in a large real‐world setting. To avoid bias from an uneven distribution between groups, we used propensity scores to adjust for factors related to tumor biology and therapy. The results demonstrated the superiority of BCS plus RT compared with mastectomy.