Postoperative Chemotherapy after Conversion Surgery for Clinical Stage IV Gastric Cancer: A Propensity Score-Matched Analysis

Background Conversion surgery following systemic chemotherapy has emerged as a promising strategy for clinical stage IV gastric cancer. However, the role of postoperative chemotherapy in improving survival outcomes remains unclear. This study aimed to evaluate the impact of postoperative chemotherapy on survival, comparing single-agent and combination regimens. Methods We conducted a single-institution retrospective study of patients who underwent gastrectomy after induction chemotherapy for clinical stage IV gastric cancer between 2007 and 2021. Patients receiving postoperative chemotherapy were categorized into single-agent and combination therapy groups. Overall survival (OS) and progression-free survival (PFS) were analyzed using Kaplan-Meier curves and Cox proportional hazard models. Propensity score matching was applied to minimize selection bias. Results Among 128 eligible patients, 45 (35.2%) received single-agent chemotherapy, while 83 (64.8%) received combination therapy. After propensity score matching, 70 patients (35 in each group) were analyzed. The median OS was 29 months, and the median PFS was 14 months, with no significant differences between single-agent and combination chemotherapy groups (OS: p = 0.841; PFS: p = 0.831). Residual tumor was a strong predictor of poor survival (p = 0.010). Subgroup analysis suggested a potential PFS benefit of combination therapy in ypStage IV patients without residual tumor (p = 0.04). Conclusion Postoperative combination chemotherapy did not significantly improve survival outcomes compared with single-agent regimen in the overall cohort. However, specific subgroups, particularly ypStage IV patients without residual tumor, may benefit from intensified therapy.