ObjectiveTo investigate the prognosis after breast conserving surgery (BCS) and modified radical mastectomy (MRM) in patients with stage Ⅰ–Ⅱ breast cancer, and analyze the factors related to locoregional recurrence (LRR).MethodsThe clinicopathologic and prognostic data of patients with stage Ⅰ–Ⅱ breast cancer who underwent the surgical treatment in the First Affiliated Hospital of Chongqing Medical University from January 2011 to December 2014 were analyzed. The clinicopathologic characteristics and prognostic differences of the BCS group and MRM group were compared. The factors related to LRR of patients underwent the BCS and MRM were analyzed.ResultsA total of 1 330 patients with stage Ⅰ–Ⅱ breast cancer were included in this study, including 230 in the BCS group and 1 100 in the MRM group. Compared with the MRM group, the patients in the BCS group had higher height (P<0.001), younger age (P<0.001), smaller tumor diameter (P<0.001), and less axillary lymph node metastasis (P<0.001). Up to August 2019, 149 cases (18 cases in the BCS group and 131 cases in the MRM group) were lost, with a follow-up rate of 88.8%. The median follow-up time was 71 months (4－103 months). The LRR rate of the BCS group was higher than that of the MRM group (6.1% versus 2.5%, χ2=7.002, P<0.01). The locoregional recurrence-free survival of the MRM group was better than that of the BCS group (χ2=7.886, P<0.01). However, there were no statistical differences between the two groups in terms of the distant metastasis-free survival and disease-free survival (P>0.05). In the patients underwent the BCS, the HER-2 was associated with the LRR (P<0.05), and the axillary lymph node metastasis was associated with the LRR in the patients underwent the MRM (P<0.05).ConclusionsAccording to results of this study, although there is a significant difference in locoregional recurrence-free survival between BCS group and MRM group in patients with stage Ⅰ–Ⅱ breast cancer, there are no statistical differences in distant metastasis-free survival and disease-free survival between the two groups. Therefore, it is safe and feasible for choosing appropriate patients with stage Ⅰ–Ⅱ breast cancer to underwent breast-conserving treatment.