Adjuvant and neoadjuvant chemotherapy for MSI early gastric cancer: a systematic review and meta-analysis

Background: Perioperative chemotherapy (CT) is an established therapeutic approach for patients diagnosed with stage IB-III gastric cancer (GC).Objectives: This study aimed to investigate the efficacy of this approach in individuals with GC exhibiting high microsatellite instability (MSI-H).Design: A systematic review was conducted, including studies that provided data on (neo)adjuvant CT outcomes in patients with MSI-H GC.Methods: Systematic searches were conducted in PubMed, Cochrane Central of Controlled Trials, and Embase databases. Data were aggregated using hazard ratios (HRs) to compare overall survival between CT and surgery.Results: Data analysis from 23 studies, including 22,011 patients, revealed that the prevalence of MSI-H is 9.8%. Administration of adjuvant or perioperative CT did not significantly reduce the risk of death or relapse in patients with MSI-H GC (HR = 0.8, 95% CI 0.54-1.16; p = 0.24 and HR = 0.84, 95% CI 0.59-1.18; p = 0.31, respectively).Conclusion: Chemotherapy did not benefit patients diagnosed with MSI-H nonmetastatic GC but rather will be integrated with immune checkpoint inhibitors in the near future.