ImportanceMinimal access breast surgery (MABS) has been used in breast cancer management. However, long-term prognostic data associated with MABS vs conventional breast surgery (CBS) are lacking.ObjectiveTo investigate long-term therapeutic outcomes associated with MABS vs CBS for breast cancer management.Design, Setting, and ParticipantsIn this single-center retrospective cohort study, 9184 individuals were assessed for inclusion. After exclusions, 2412 adult female individuals were included who were diagnosed with stage 0 to III breast cancer, underwent unilateral breast surgery between January 2004 and December 2017, and had no distant metastasis or history of severe underlying disease. Propensity score matching was performed to minimize selection bias. Data were analyzed from January 1, 2004, to December 31, 2019.ExposuresMABS or CBS.Main Outcomes and MeasuresData on demographic and tumor characteristics and long-term outcomes were collected and analyzed.ResultsThis study included 2412 patients (100% female; median [IQR] age, 44 [40-49] years). Of these, 603 patients underwent MABS (endoscopic, endoscopy-assisted, or robot-assisted procedures in 289, 302, and 12 patients, respectively) and 1809 patients underwent CBS. The median follow-up time was 84 months (93 in the MABS group and 80 months in the CBS group). Intergroup differences were not significant for the following parameters: 10-year local recurrence-free survival (93.3% vs 96.3%; hazard ratio [HR], 1.39; 95% CI, 0.86-2.27; P = .18), regional recurrence-free survival (95.5% vs 96.7%; HR, 1.38; 95% CI, 0.81-2.36; P = .23), and distant metastasis-free survival (81.0% vs 82.0%; HR, 0.95; 95% CI, 0.74-1.23; P = .72). The 5-, 10-, and 15-year disease-free survival rates in the MABS group were 85.9%, 72.6%, and 69.1%, respectively. The corresponding rates in the CBS group were 85.0%, 76.6%, and 70.7%. The intergroup differences were not significant (HR, 1.07; 95% CI, 0.86-1.31; P = .55). The 5-, 10-, and 15-year overall survival rates in the MABS group were 92.0%, 83.7%, and 83.0%, respectively. The corresponding rates in the CBS group were 93.6%, 88.7%, and 81.0%. The intergroup differences were not significant (HR, 1.29; 95% CI, 0.97-1.72; P = .09). Post hoc subgroup analysis showed no significant intergroup differences in disease-free survival.Conclusions and RelevanceIn this cohort study, long-term outcomes following MABS were not significantly different from those following CBS in patients with early-stage breast cancer. MABS may be a safe and feasible alternative in this patient population.