Background:Inflammation-based indexes have been used to predict survival and recurrence in cancer patients.Systemic immune-inflammation index(Sll) was reported to be associated with prognosis in some malignant tumors.In the present study,we aimed to explore the association between Sll and the prognosis of patients with gastric cancer.Methods:We retrospectively analyzed data from 444 gastric cancer patients who underwent gastrectomy at the First Affiliated Hospital of Sun Yat-sen University between January 1994 and December 2005.Preoperative Sll was calculated.The Chi square test or Fisher’s exact test was used to determine the relationship between preoperative Sll and clinicopathologic characteristics.Overall survival(OS) rates were estimated using the Kaplan-Meier method,and the effect of Sll on OS was analyzed using the Cox proportional hazards model.Receiver operating characteristic(ROC)curves were used to compare the predictive ability of Sll,NLR,and PLR.Results:Sll equal to or higher than 660 was significantly associated with old age,large tumor size,unfavorable Borrmann classification,advanced tumor invasion,lymph node metastasis,distant metastasis,advanced TNM stage,and high carcino-embryonic antigen level,high neutrophil-lymphocyte ratio,and high platelet-lymphocyte ratio(all P<0.05).High Sll was significantly associated with unfavorable prognosis(P<0.001) and Sll was an independent predictor for OS(P=0.015).Subgroups analysis further showed significant associations between high Sll and short OS in stage Ⅰ,Ⅱ,Ⅲ subgroups(all P<0.05).Sll was superior to NLR and PLR for predicting OS in patients with gastric cancer.Conclusion:Preoperative Sll level is an independent prognostic factor for OS in patients with gastric cancer. Background: Inflammation-based indexes have been used to predict survival and recurrence in cancer patients. Systematically immune-inflammation index (Sll) was reported to be associated with prognosis in some malignant tumors. In the present study, we aimed to explore the association between Sll and the prognosis of patients with gastric cancer. Methods: We retrospectively analyzed data from 444 gastric cancer patients who underwent gastrectomy at the First Affiliated Hospital of Sun Yat-sen University between January 1994 and December 2005. Preoperative Sll was calculated. Chi Square test or Fisher’s exact test was used to determine the relationship between preoperative Sll and clinicopathologic characteristics. Overall survival (OS) rates were estimated using the Kaplan-Meier method, and the effect of S11 on OS was analyzed using the Cox proportional hazards model. Receiver operating characteristic (ROC) curves were used to compare the predictive ability of Sll, NLR, and PLR. Results: Sll equal to or hig her than 660 was significantly associated with old age, large tumor size, unfavorable Borrmann classification, advanced tumor invasion, lymph node metastasis, distant metastasis, advanced TNM stage, and high carcino-embryonic antigen level, high neutrophil-lymphocyte ratio, and high platelet (all P <0.05). High Sll was significantly associated with unfavorable prognosis (P <0.001) and Sll was an independent predictor for OS (P = 0.015) .Subgroups analysis further showed significant associations between high S11 and short OS in Stage I, II, III subgroups (all P <0.05) .Sll was superior to NLR and PLR for predicting OS in patients with gastric cancer. Confc: Preoperative Sll level is an independent prognostic factor for OS in patients with gastric cancer.