Objective:Conversion surgery is a surgery with a purpose of R0 resection in primary advanced gastric cancer (GC) that responded well to systemic chemotherapy.This study aimed to explore the efficacy of conversion surgery for advanced GC.Methods:A total of 618 advanced GC patients receiving systemic chemotherapy were stratified into low-,moderate-and high-risk groups based on a nomogram-predicted probability of overall survival.The survival of conversion surgery and chemotherapy alone groups was compared using the log-rank test and Cox regression analysis after propensity score matching (PSM).Results:A nomogram with good discrimination (concordance index:0.65) and accurate calibration was constructed.After PSM,the median survival time (MST) of conversion surgery was 26.80 months,compared with 16.60 months of chemotherapy alone (P＜0.001).Conversion surgery was associated with a longer MST for patients in the low-risk group (30.40 months vs.20.90 months,P=0.013),whereas it was not associated with prolonged survival in the moderate-and high-risk groups (P=0.221 and P=0.131,respectively).Conclusions:Conversion surgery was associated with longer survival,especially for low-risk population.