Early Oncologic Outcomes of Robot-Assisted Versus Conventional Nipple-Sparing Mastectomy: A Propensity Score-Matching Analysis

Background: Robot-assisted nipple-sparing mastectomy (R-NSM) was developed to minimize visible scarring and improve the quality of life in patients with breast cancer. However, despite its increasing adoption, evidence regarding its oncologic outcomes remains sparse. This study aimed to compare the oncologic outcomes of R-NSM and conventional nipple-sparing mastectomy (C-NSM). Methods: We retrospectively reviewed patients who underwent NSM with immediate breast reconstruction for breast cancer between 2019 and 2022. Risk-reducing cases were excluded. R-NSM and C-NSM groups were compared after propensity score matching using a nearest-neighbor algorithm, matching each patient in the R-NSM group to up to five controls without replacement. Results: Before matching, the R-NSM group more frequently had hormone receptor-positive/human epidermal growth factor receptor 2-negative tumors, lower Ki-67 indices, and no neoadjuvant chemotherapy. After propensity score matching, most clinicopathologic variables were well balanced between groups. During a median follow-up of 37.5 months for R-NSM and 42.6 months for C-NSM, no locoregional recurrence, distant metastasis, or death occurred in the R-NSM group, whereas all seven recurrences (3.5%) occurred in the C-NSM group. Kaplan–Meier analysis showed no significant differences in locoregional recurrence-free survival, distant metastasis-free survival, or disease-free survival between groups, although all observed oncologic events occurred in the C-NSM group. Conclusion: R-NSM demonstrated oncologic outcomes comparable to those of C-NSM, with no recurrence or mortality despite a sufficiently long follow-up. These findings support R-NSM as a feasible and oncologically sound surgical option for appropriately selected patients with early-stage breast cancer.