Objective:Systemic chemotherapy has limited efficacy in the treatment of peritoneal metastasis(PM)in gastric cancer(GC).Hyperthermic intraperitoneal chemotherapy(HIPEC)combined with complete cytoreductive surgery(CRS)has shown promising outcomes but remains controversial.The present study aimed to evaluate the safety and efficacy of HIPEC without CRS in GC patients with PM.Methods:This retrospective propensity score-matched multicenter cohort study included GC patients with PM treated with either chemotherapy alone(Cx group)or with HIPEC combined with chemotherapy(HIPEC-Cx group)in four Chinese high-volume gastric medical centers between 2010 and 2017.The primary outcomes were median survival time(MST)and 3-year overall survival(OS).Propensity score matching was performed to compensate for controlling potential confounding effects and selection bias.Results:Of 663 eligible patients,498 were matched.The MST in the Cx and HIPEC-Cx groups was 10.8 and 15.9 months,respectively[hazard ratio(HR)=0.71,95％confidence interval(95％CI),0.58-0.88; P=0.002].The 3-year OS rate was 10.1％(95％CI,5.4％-14.8％)and 18.4％(95％CI,12.3％-24.5％)in the Cx and HIPEC-Cx groups,respectively(P=0.017).The complication rates were comparable.The time to first flatus and length of hospital stay for patients undergoing HIPEC combined with chemotherapy was longer than that of chemotherapy alone(4.6±2.4 d vs.2.7±1.8 d,P＜0.001; 14.2±5.8 d vs.11.4±7.7 d,P＜0.001),respectively.The median follow-up period was 33.2 months.Conclusions:Compared with standard systemic chemotherapy,HIPEC combined with chemotherapy revealed a statistically significant survival benefit for GC patients with PM,without compromising patient safety.