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.