Pathologic complete response and breast cancer survival post-neoadjuvant chemotherapy: A systematic review and meta-analysis of real-world data.

Abstract

e12625 Background: Breast cancer is the most frequently diagnosed cancer and a major cause of cancer mortality among women worldwide. Neoadjuvant chemotherapy (NAC) plays a vital role in breast cancer management by reducing tumor size, increasing rates of breast-conserving surgery, and improving outcomes through pathologic complete response (pCR). Achieving pCR is linked to better long-term survival, especially in aggressive subtypes like triple-negative (TNBC) and HER2-positive breast cancer. This study aims to conduct a systematic review and meta-analysis of retrospective RWD studies evaluating BC patients treated with NAC, with the goal of correlating pCR with Overall Survival (OS) and Disease-free Survival (DFS). Methods: A systematic search of PubMed, Embase, LILACS, and Cochrane Library identified retrospective studies published between 1999 and 2024. Data from 22 studies involving 12,115 patients were analyzed. The primary endpoints were OS and DFS, stratified by pCR status and tumor subtype. Hazard ratios (HR) and confidence intervals (CI) were pooled, and heterogeneity was assessed using I² and Chi-square tests. Results: Among 12,115 patients, 2,536 (20.9%) achieved pCR. pCR rates were highest in HER2-positive (44.4%) and TNBC (31.3%) subtypes. pCR was associated with a 30% improvement in OS (HR: 1.30; 95% CI: 1.28–1.33; p < 0.00001) and a 29% improvement in DFS (HR: 1.29; 95% CI: 1.24–1.32; p < 0.00001). TNBC patients with pCR had a 51% increase in DFS (HR: 1.51; 95% CI: 1.19–1.93; p = 0.0008). Of the 22 included studies, 70% were categorized as having a low overall risk of bias. Heterogeneity (I² = 96%) was observed across studies. Conclusions: pCR serves as a robust predictor of enhanced OS and DFS, particularly in aggressive breast cancer subtypes such as TNBC and HER2-positive. These findings underscore the importance of strategies aimed at increasing pCR rates to improve long-term survival and disease control in breast cancer patients.