A Propensity Score-matched Analysis of Long-term Oncologic Outcomes After Nipple-sparing Versus Conventional Mastectomy for Locally Advanced Breast Cancer

Objectives: To compare the long-term oncologic outcomes of nipple-sparing mastectomy (NSM) with those of conventional mastectomy (CM) in patients with locally advanced breast cancer (LABC) receiving neoadjuvant chemotherapy (NACT). Summary of Background Data: NSM has been increasingly implemented in patients with breast cancer. However, oncologic efficacy of NSM in patients with LABC has not been sufficiently demonstrated. Methods: The study group comprised 850 patients with clinical stage IIB to IIIC breast cancer who underwent NACT followed by either NSM and immediate breast reconstruction or CM alone. After propensity score-matching, 418 patients were included in the analysis. Local recurrence-free survival, disease-free survival (DFS), distant metastasis-free survival, and overall survival (OS) rates were calculated using the Kaplan-Meier method and compared using log-rank tests between the NSM and CM groups. Results: After matching, the mean follow-up period was 70 +/- 25 months for the NSM group and 74 +/- 27 months for the CM group (P = 0.181). There were no significant differences between the groups in terms of 6-year local recurrence-free survival (91.6% vs. 95.8%; P = 0.239), DFS (70.5% vs. 73.4%; P = 0.583), distant metastasis-free survival (79.8% vs. 77.4%; P = 0.320), or OS (87.6% vs. 84.8%; P = 0.465) rates. Additionally, we identified 30 patients in the NSM group who initially presented with tumor extension in the subareolar area; the nipple-areola complex was successfully preserved after NACT, and no recurrence at the nipple was observed in these patients. Conclusions: In this matched control study, we demonstrated comparable long-term oncologic outcomes between NSM with immediate reconstruction and CM alone after NACT for LABC. In patients who had tumors extending to the subareolar area before NACT, NSM can be tried if tumor involvement of the nipple-areola complex appears resolved on imaging studies after chemotherapy.