Timing of chemotherapy in breast cancer: A meta-analytic evaluation of neoadjuvant versus adjuvant approaches on survival, response, and surgical outcomes.

e12543 Background: Neoadjuvant chemotherapy (NACT) has become increasingly utilized in breast cancer management, offering potential advantages including tumor downstaging and increased breast conserving surgery rates. However, the comparative efficacy of NACT versus adjuvant chemotherapy (ACT) across multiple oncologic outcomes remains an area of active investigation. Following systematic review and meta-analysis evaluates the outcomes comparing NACT versus ACT in breast cancer patients. Methods: A systematic literature search was performed across multiple databases to identify randomized controlled trials, non-randomized controlled trials, retrospective studies, and observational cohorts comparing NACT versus ACT in breast cancer patients.outcomes including overall survival (OS), disease-free survival (DFS), distant recurrence, and locoregional recurrence. Risk ratios (RR) with 95% confidence intervals (CI) were calculated using random effects models. Heterogeneity was assessed using I² statistics. Results: The meta-analysis included data from multiple studies encompassing over 4,000 patients. For OS, pooled analysis of 2,365 patients in the NACT group versus 1,995 in the ACT group demonstrated no significant difference (RR 0.83, 95% CI 0.69–1.01; P = 0.07; I² = 91%). Similarly, DFS analysis (n = 3,301) showed comparable outcomes between groups (RR 1.03, 95% CI 0.93–1.14; P = 0.54; I² = 54%). Neither distant recurrence (RR 1.11, 95% CI 0.78–1.60; P = 0.56; I² = 88%) nor locoregional recurrence (RR 1.18, 95% CI 0.80–1.76; P = 0.41; I² = 76%) differed significantly between NACT and ACT groups. Substantial heterogeneity was observed across outcomes, likely reflecting differences in chemotherapy regimens, patient populations, and study designs. Conclusions: This meta-analysis demonstrates that NACT and ACT provide comparable long-term oncologic outcomes in breast cancer, with no significant differences in OS, DFS, distant recurrence, or locoregional recurrence. These findings support current guideline recommendations that NACT is an appropriate alternative to ACT, particularly when tumor downstaging for breast-conserving surgery is desired. The high heterogeneity observed underscores the need for subgroup analyses by breast cancer subtype and treatment regimen in future studies.