Comparison of Breast-Conserving Surgery vs. Mastectomy for Patients with Breast Cancer after Neoadjuvant Chemotherapy

Abstract

<h3>Purpose/Objective(s)</h3> To compare recurrence and survival outcomes between breast-conserving surgery (BCS) and mastectomy after neoadjuvant chemotherapy (NACT). <h3>Materials/Methods</h3> A total of 730 eligible patients who underwent NACT between 2000 and 2014 were retrospectively reviewed. Of those, 104 (14.2%) patients received BCS and 626 (85.8%) patients received mastectomy. Locoregional recurrence (LRR), distant metastases (DM), disease-free survival (DFS), Breast cancer - specific survival (BCSS) and overall survival (OS) were estimated using the Kaplan-Meier method. The impact of BCS versus (vs) mastectomy on outcomes was assessed by multivariate Cox models and inverse probability of treatment weighting (IPTW) method by adjusting for age, clinical T stage, clinical N stage, NACT cycles, histological grade, lymphovascular invasion (LVI), molecular subtype/trastuzumab, ypT (pathologic tumor stage after NACT), ypN (pathologic lymph node stage after NACT), endocrine therapy, and adjuvant chemotherapy. Recurrence and survival curves before or after weighting were compared with the log rank test. <h3>Results</h3> The median follow-up was 87.4 months. The 5-year LRR, DM, DFS, BCSS and OS rates after BCS and mastectomy were 6.9% vs 7.6% (P = 0.805), 10.8% vs 19.9% (P = 0.145), 83.4% vs 78.2% (P = 0.514), 98.9% vs 90.4% (P = 0.005) and 98.9% vs 90.1% (P = 0.003), respectively. There were significant differences in distribution of most baseline characteristics between the BCS and mastectomy group. After IPTW adjustment, the clinical characteristics between two groups were comparable. Multivariate analysis showed that BCS had no significant impact on LRR (HR 1.08, 95% CI 0.48-2.43, P = 0.849), DM (HR 0.82, 95% CI 0.49-1.40, P = 0.473) and DFS (HR 1.12, 95% CI 0.70-1.80, P = 0.626) compared with mastectomy, but BCS significantly improved BCSS (HR 0.29, 95% CI 0.09-0.92, P = 0.035) and OS (HR 0.27, 95% CI 0.08-0.86, P = 0.027) compared with mastectomy. After IPTW adjustment, the results of 5-year LRR, DM, DFS remained the same, which were 10.0% vs 7.3% (P = 0.598), 11.7% vs 19.0% (P = 0.341), 78.6% vs 79.1% (P = 0.908) for BCS and mastectomy groups, respectively. The 5-year BCSS and OS were better in the BCS group than in the mastectomy group, but the difference was no longer statistically significant (BCSS: 99.7% vs. 90.8%, <i>P</i> = 0.095 and OS: 99.7% vs. 90.6%, <i>P</i> = 0.083). <h3>Conclusion</h3> Locoregional and distant control and DFS are comparable with BCS and mastectomy, but BCSS and OS may be better with BCS. Thus, BCS is a safe treatment option for selected breast cancer patients after NACT.