Disease-free and overall survival after neoadjuvant chemotherapy in breast cancer: breast-conserving surgery compared to mastectomy in a large single-centre cohort study

PURPOSE: The extended role of breast-conserving surgery (BCS) in the neoadjuvant setting may raise concerns on the oncologic safety of BCS compared to mastectomy. This study compared long-term outcomes after neoadjuvant chemotherapy (NAC) between patients treated with BCS and mastectomy. METHODS: All breast cancer patients treated with NAC from 2008 until 2017 at the Amphia Hospital (the Netherlands) were included. Disease-free and overall survival were compared between BCS and mastectomy with survival functions. Multivariable Cox proportional hazard regression was performed to determine prognostic variables for disease-free survival. RESULTS: 561 of 612 patients treated with NAC were eligible: 362 (64.5%) with BCS and 199 (35.5%) with mastectomy. Median follow-up was 6.8 years (0.9–11.9). Mastectomy patients had larger tumours and more frequently node-positive or lobular cancer. Unadjusted five-year disease-free survival was 90.9% for BCS versus 82.9% for mastectomy (p = .004). Unadjusted five-year overall survival was 95.3% and 85.9% (p < .001), respectively. In multivariable analysis, clinical T4 (cT4) (HR 3.336, 95% CI 1.214–9.165, p = .019) and triple negative disease (HR 5.946, 95% CI 2.703–13.081, p < .001) were negative predictors and pathologic complete response of the breast (HR 0.467, 95% CI 0.238–0.918, p = .027) and axilla (HR 0.332, 95% CI 0.193–0.572, p = .001) were positive predictors for disease-free survival. Mastectomy versus BCS was not a significant predictor for disease-free survival when adjusted for the former variables (unadjusted HR 2.13 (95%CI: 1.4–3.24), adjusted HR 1.31 (95%CI: 0.81–2.13)). In the BCS group, disease-free and overall survival did not differ significantly between cT1, cT2 or cT3 tumours. CONCLUSION: BCS does not impair disease-free and overall survival in patients treated with NAC. Tumour biology and treatment response are significant prognostic indicators.