Immune Checkpoint Inhibitors Improve Outcomes Following Conversion Surgery in Stage IV Gastric Cancer

Background: Stage IV gastric cancer remains challenging to treat despite recent advances in systemic therapy. Among patients with favorable responses to chemotherapy, conversion surgery aiming for R0 resection has shown promise in improving survival. Immune checkpoint inhibitors (ICIs) have become a key component of systemic treatment, but their prognostic impact in the setting of conversion surgery remains unclear. Methods: This retrospective single-center study included 98 patients with gastric cancer who underwent platinum-based doublet chemotherapy followed by minimally invasive surgery. Patients were stratified into ICI (n=41) and non-ICI (n=57) groups. Perioperative outcomes, progression-free survival (PFS), and overall survival (OS) were evaluated using Kaplan-Meier analysis and Cox regression models. Results: The median operative time was 345 minutes, and median blood loss was 5 ml. R0 resection was achieved in 79.6% of cases, and the median hospital stay was 7 days. Complications ≥ Clavien-Dindo grade II occurred in 12.2% of patients. ICI-treated patients had significantly longer PFS (HR 0.418, P=0.0008) and OS (HR 0.437, P=0.024). R0 resection was independently associated with improved PFS (HR 0.179, P<0.0001) and OS (HR 0.231, P<0.0001). Multivariate analysis identified pathological N status, R0 resection, and ICI use as independent predictors of PFS. Conclusion: ICI-based therapy may enhance resectability and long-term survival in patients undergoing conversion surgery for advanced gastric cancer. Further research is warranted to optimize patient selection and perioperative management in this evolving treatment paradigm.