Real-world evidence of neoadjuvant chemotherapy for breast cancer treatment in a Brazilian multicenter cohort: Correlation of pathological complete response with overall survival

OBJECTIVES: We aimed to evaluate the pCR rate in patients receiving NAC for the treatment of breast cancer (BC) in a multicenter cohort in Brazil. Additionally, we aimed to use RWD to assess the impact of pCR on OS and DFS. METHODS: This was a retrospective, multicenter cohort study that included female patients over 18 years of age who were diagnosed with nonmetastatic breast cancer and received NAC. OS and DFS at five years were estimated by the Kaplan‒Meier method. Additionally, we conducted a multivariate analysis to identify factors that were significantly associated with pCR and OS. RESULTS: From 2011 to 2020, 1891 patients were included in the study, and 421 (22,3%) achieved pCR (ypT0 ypN0). Considering the presence of residual DCIS, pCR was achieved in 467 patients (23,5%). The pCR rate varied between the subtypes: HER-2+ (p = 0,016) and clinical stage IIIA and IIIB (p < 0,001). Among HER-2+ patients, those who received trastuzumab had a significantly higher pCR rate than those who did not receive trastuzumab (p < 0.0001). Similarly, patients with TNBC who received treatment with platinum-based regimens also showed higher pCR rates (p < 0.0001). OS was grouped according to pCR status, and the OS rate was 88,3% in the pCR group and 58.1% in the non-pCR group (p < 0.0001). The five-year DFS was 92.2% in the pCR group and 64.3% in the non-pCR group (p < 0.0001). CONCLUSION: The pCR rate and its prognostic value varied across BC subtypes. In our study, pCR could be used as a surrogate of favorable clinical outcome, as it was associated with higher OS and DFS rates.