AIM: To assess the prognostic significance of immunological and nutritional-based indices, including the prognostic nutritional index(PNI), neutrophillymphocyte ratio(NLR), and platelet-lymphocyte ratio in gastric cancer.METHODS: We retrospectively reviewed 632 gastric cancer patients who underwent gastrectomy between1998 and 2008. Areas under the receiver operating characteristic curve were calculated to compare the predictive ability of the indices, together with estimating the sensitivity, specificity and agreement rate.Univariate and multivariate analyses were performed to identify risk factors for overall survival(OS). Propensity score analysis was performed to adjust variables to control for selection bias.RESULTS: Each index could predict OS in gastric cancer patients in univariate analysis, but only PNI had independent prognostic significance in multivariate analysis before and after adjustment with propensity scoring(hazard ratio, 1.668; 95% confidence interval:1.368-2.035). In subgroup analysis, a low PNI predicted a significantly shorter OS in patients with stage Ⅱ-Ⅲ disease(P = 0.019, P < 0.001), T3-T4 tumors(P <0.001), or lymph node metastasis(P < 0.001). Canton score, a combination of PNI, NLR, and platelet, was a better indicator for OS than PNI, with the largest area under the curve for 12-, 36-, 60-mo OS and overall OS(P = 0.022, P = 0.030, P < 0.001, and P = 0.024,respectively). The maximum sensitivity, specificity, and agreement rate of Canton score for predicting prognosis were 84.6%, 34.9%, and 70.1%, respectively.CONCLUSION: PNI is an independent prognostic factor for OS in gastric cancer. Canton score can be a novel preoperative prognostic index in gastric cancer. AIM: To assess the prognostic significance of immunological and nutritional-based indices, including the prognostic nutritional index (PNI), neutrophillymphocyte ratio (NLR), and platelet-lymphocyte ratio in gastric cancer. METHODS: We retrospectively reviewed 632 gastric cancer patients who underwent gastrectomy between1998 and 2008. Areas under the receiver operating characteristic curve were calculated to compare the predictive ability of the indices, together with estimating the sensitivity, specificity and agreement rate .Univariate and multivariate analyzes were performed to identify risk factors for overall survival (OS) . Propensity score analysis was performed to adjust variables to control for selection bias .RESULTS: Each index could predict OS in gastric cancer patients in univariate analysis, but only PNI had independent prognostic significance in multivariate analysis before and after adjustment with propensity scoring (hazard ratio , 1.668; 95% confidence interval: 1.368-2.035) n subgroup analysis, a low PNI predicted a significantly shorter OS in patients with stage II-III disease (P = 0.019, P <0.001), T3-T4 tumors (P <0.001), or lymph node metastasis (P <0.001). Canton score, a combination of PNI, NLR, and platelet, was a better indicator for OS than PNI, with the largest area under the curve for 12-, 36-, 60-mo OS and overall OS (P = 0.022, The maximum sensitivity, specificity, and agreement rate of Canton score for predicting prognosis were 84.6%, 34.9%, and 70.1%, respectively. CONCLUSION: PNI is an independent prognostic factor for OS in gastric cancer. Canton score can be a novel preoperative prognostic index in gastric cancer.