Survival benefit of conversion surgery after intensive chemotherapy for unresectable metastatic gastric cancer: a propensity score-matching analysis.

PURPOSE The clinical benefit of conversion surgery (CS) for unresectable gastric cancer (GC), whereby unresectable GC responds to chemotherapy and subsequently receives curative-intent surgery, remains unclear. Here, we aimed to clarify the clinical value of CS. METHODS In this retrospective cohort study, we analyzed 175 unresectable GC, who received triple combined chemotherapy between 2004 and 2019. We divided patients into two groups: those who underwent CS and those receiving chemotherapy only (CS and C groups, respectively). Propensity score matching was used to minimize confounding bias. RESULTS Of 175 cases, 61 (34.9%) underwent CS. R0 resection was obtained in 85.2%. After matching, 44 pairs were selected; there were no significant differences in baseline covariants. Group CS had a significantly better median overall survival (OS) (18.8 vs. 46.0 months, p < 0.001), and prolonged progression-free survival (7.4 vs. 25.8 months, p < 0.001). Subgroup analysis of OS showed a favorable trend for CS for almost all subgroups. Multivariate analysis revealed that good ECOG performance status and CS were associated with a longer OS. CONCLUSION The survival benefit of CS was consistently demonstrated in the univariate and multivariate analysis, even in the matched cohort. Additional large-scale trials are needed for further validation.