Efficacy of adjuvant S-1 vs capecitabine plus oxaliplatin (XELOX) chemotherapy among gastric cancer patients after D2 gastrectomy: A systematic review and meta-analysis.

e16115 Background: Adjuvant chemotherapy improves outcomes after D2 gastrectomy for gastric cancer. S-1 and XELOX are commonly used regimens, but their relative efficacy remains uncertain. We conducted a systematic review and meta-analysis comparing S-1 therapy with XELOX in gastric cancer patients undergoing D2 gastrectomy. Methods: We conducted a comprehensive literature search across five databases: PubMed, Cochrane, Scopus, Embase, and ClinicalTrials.gov for articles comparing efficacy and safety of S-1 vs XELOX adjuvant chemotherapies in gastric cancer patients after D2 gastrectomy. Nine studies fulfilling the eligibility criteria were included in the review and analysis. The analysis was conducted on RStudio v4.5.0 using the 'meta' package. The generic inverse variance method was used for continuous data, and the Mantel–Haenszel method was used for binary data. The pooled analysis is presented as hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (CIs). Results: Nine studies evaluating S-1 vs XELOX were included. There was no significant difference in DFS (HR: 0.94, 95% CI: 0.72 – 1.22; p-value = 0.634; I 2 = 88.1%) or OS (HR: 0.85, 95% CI: 0.59 – 1.21; p-value = 0.363; I 2 = 79%) between the two regimens. One-year DFS (OR: 1.26, 95% CI: 0.71 – 2.23; p = 0.421; I 2 = 76.9%), 3-year DFS (OR: 1.18, 95% CI: 0.75 – 1.85; p = 0.483; I 2 = 85.3%), and 5-year DFS (OR: 1.34, 95% CI: 0.95 – 1.89; p = 0.101; I 2 = 74.4%) were similar between S-1 and XELOX. Likewise, 1-year OS, 3-year OS, and 5-year OS showed no significant differences between the two regimens: (OR: 0.97, 95% CI: 0.33 – 2.90; p = 0.961; I 2 = 86.6%), (OR: 1.20, 95% CI: 0.69 – 2.08; p = 0.517; I 2 = 85.3%), and (OR: 1.55, 95% CI: 0.99 – 2.42; p = 0.054; I 2 = 87.7%), respectively. Heterogeneity was moderate to high across outcomes, but results were robust on sensitivity analyses. Conclusions: Among gastric cancer patients following D2 gastrectomy, adjuvant S-1 demonstrates efficacy comparable to XELOX, with no significant differences observed in disease-free or overall survival across short- and long-term follow-up.