Survival outcomes of neoadjuvant versus adjuvant chemotherapy in triple-negative breast cancer: a meta-analysis of 36,480 cases

Background The survival outcomes of neoadjuvant chemotherapy (NACT) versus adjuvant chemotherapy (ACT) for patients with triple-negative breast cancer (TNBC) remain unclear. Therefore, in this study, a meta-analysis was conducted to analyze current evidence on the survival outcomes of NACT versus ACT in TNBC. Methods A systematic search was performed on the PubMed and Embase databases to identify relevant articles investigating the survival outcomes of NACT versus ACT in TNBC. Results A total of nine studies involving 36,480 patients met the selection criteria. Among them, 10,728 (29.41%) received NACT, and 25,752 (70.59%) received ACT. The pathological complete response (pCR) rate was 35% (95% CI = 0.23-0.48). Compared with ACT, the overall survival (OS) of NACT was poor (HR = 1.59; 95% CI = 1.25-2.02;P =0.0001), and there was no significant difference in disease-free survival (DFS) between the two treatments (HR = 0.85; 95% CI = 0.54-1.34;P= 0.49). NACT with pCR significantly improved the OS (HR = 0.53; 95% CI = 0.29-0.98;P= 0.04) and DFS (HR = 0.52; 95% CI = 0.29-0.94;P= 0.03), while the OS (HR = 1.18; 95% CI = 1.09-1.28;P< 0.0001) and DFS (HR = 2.36; 95% CI = 1.42-3.89;P= 0.0008) of patients with residual disease (RD) following NACT were worse compared to those receiving ACT. Conclusion These findings suggest that, for TNBC, NACT with pCR is superior to ACT in improving OS and DFS, and it turns to be opposite when patients are receiving NACT with RD.