Adjuvant chemotherapy for breast cancer after preoperative chemotherapy: A propensity score matched analysis

International audienceAlthough identified to be at a higher risk of relapse, no consensus exists on the treatment of breast cancer (BC) patients with no pathological complete response after neoadjuvant chemotherapy (NAC). The benefit of adjuvant chemotherapy (ADJ) in this context has scarcely been studied. We evaluated the benefit of administrating adjuvant chemotherapy in a real life cohort of BC patients with invasive residual disease after NAC. 1199 female BC patients with T1-3NxM0 invasive tumors receiving NAC at Institut Curie from 2002 to 2012 were included in the analysis. 1061 had been treated by NAC only, whereas 138 had received additional adjuvant chemotherapy after NAC (FUN protocol: 5-FU-Vinorelbine). We compared disease-free survival (DFS) and overall survival (OS) rates between patients having received NAC only and patients having received NAC+ADJ. To ensure comparability of our populations, we used a propensity score (which defines the probability of treatment assignment conditional on observed baseline covariates) and matched each patient having received NAC+ADJ (n = 138) with a patient having received NAC only that had a similar propensity score value. Before propensity score matching, DFS and OS rates were significantly lower in the NAC+ADJ group compared to NAC only, after 3 years, 5 years and 10 years follow-up (p