Oncologic safety of breast conservation following NACT in women with locally advanced breast cancer

INTRODUCTION: Breast conservation surgery (BCS) is the accepted standard of treatment for early breast cancer, with evidence from randomized controlled and population-based studies. The oncological outcome of BCS in locally advanced breast cancer (LABC) is mainly available from retrospective series with a small sample size and a shorter follow-up duration. METHODS: A retrospective observational study of 411 non-metastatic LABC patients who received neoadjuvant chemotherapy (NACT) followed by surgery from 2011 to 2016. We retrieved the data from a prospectively maintained database and electronic medical records. Survival data were analyzed by Kaplan–Meier curves and Cox regression using Statistical Package for the Social Sciences 25 and STATA 14. RESULTS: 146/411 (35.5%) women had BCS with a margin positivity rate of 3.42%. With a median follow-up of 64 months (IQR 61, 66), the local relapse rate was 8.9% in BCS and 8.3% after mastectomy. The estimated 5-year locoregional recurrence-free survival (LRFS), recurrence-free survival (RFS), distant disease-free survival (DDFS) and overall survival (OS) rates of BCS were 86.9%, 63.9%, 71% and 79.3%, and 90.1%, 57.9%, 58.3% and 71.5% in the mastectomy group. On univariate analysis, BCS showed superior survival outcomes compared to mastectomy (unadjusted HR (95% CI) for RFS: 0.70 (0.50–1), DDFS: 0.57 (0.39–0.84), OS: 0.58 (0.36–0.93)). After adjusting for age, cT stage, cN stage, poorer chemotherapy response (ypT0/is, N0) and radiotherapy, BCS and mastectomy groups were found comparable in terms of LRFS (HR: 1.1, 0.53–2.3), DDFS (HR: 0.67, 0.45–1.01), RFS (HR: 0.80, 0.55–1.17) and OS (HR: 0.69, 0.41–1.14). CONCLUSION: BCS is technically feasible in LABC patients. LABC patients who respond well to NACT can be offered BCS without compromising survival outcomes.