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

Breast cancer is a leading cause of cancer-related mortality worldwide, and neoadjuvant chemotherapy (NAC) plays a pivotal role in its management by reducing tumor size, enabling breast-conserving surgery, and improving survival outcomes. Achieving pathologic complete response (pCR) is strongly associated with better overall survival (OS) and disease-free survival (DFS), particularly in aggressive subtypes such as triple-negative (TNBC) and HER2-positive breast cancers. This systematic review and meta-analysis evaluated the correlation between pCR, OS, and DFS in breast cancer patients treated with NAC, focusing exclusively on real-world data (RWD). A comprehensive search with PRISMA guidelines of major databases from 1999 to 2024 identified 22 retrospective studies comprising 12,115 patients. Hazard ratios (HRs) and confidence intervals (CIs) were pooled using random-effects models, and heterogeneity was assessed using the I2 statistic. pCR was achieved in 20.9 % of patients, with higher rates in HER2-positive (44.4 %) and TNBC (31.3 %) subtypes. Achieving pCR was associated with a 30 % improvement in OS (HR: 1.30; 95 % CI: 1.28–1.33) and a 29 % improvement in DFS (HR: 1.29; 95 % CI: 1.24–1.32). Among TNBC patients, pCR correlated with a 51 % increase in DFS (HR: 1.51; 95 % CI: 1.19–1.93). Significant heterogeneity (I2 = 96 %) was observed across studies. These findings highlight the importance of pCR as a robust predictor of improved survival outcomes in breast cancer, particularly in TNBC and HER2-positive subtypes, and underscore the need for strategies to increase pCR rates to enhance long-term survival and disease control.