Abstract: Objective To investigate the value of platelet to lymphocyte ratio (PLR), neutrophil tolymphocyte ratio (NLR) and C-reactive protein (CRP) in evaluating peritoneal metastasis of advanced gastric cancer. 
Methods A total of 124 patients with advanced gastric cancer in Xuzhou Cancer Hospital were retrospectively selected and divided into peritoneal metastasis group (n=36) and non-peritoneal metastasis group (n=88) according to the occurrence of peritoneal metastasis. The clinical data, pathological parameters,CRP, PLR, NLR were compared between the two groups, to analyze the influencing factors of peritoneal metastasis of advanced gastric cancer. Logistic regression model was constructed, and receiver operating characteristic (ROC) curve was used to evaluate its predictive value for peritoneal metastasis. 
Results The tumor diameter of the abdominal metastasis group was higher than that of the non-abdominal metastasis group, the invasion depth, TNM stage, and PLR, NLR, CRP levels were higher than those of the abdominal metastasis group, and the degree of histological differentiation was lower than that of the non-abdominal metastasis group (P＜0.05). After excluding confounding factors such as tumor size, invasion depth, TNM stage and histological differentiation, the Logistic model was established and multivariate analysis was performed. PLR, NLR and CRP were found to be risk factors for peritoneal metastasis in advanced gastric cancer (P＜0.05). The risk prediction model was constructed: logit (p) =PLR×1.416+NLR×1.149+CRP×1.088. As for predictive value of the model, when logit (p) > 0.5, the AUC value was 0.755, χ2 was 10.212, the diagnostic sensitivity was 80.95%, and the specificity was 61.64%. 
Conclusion Peritoneal metastasis of advanced gastric cancer is correlated with the levels of PLR, NLR and CRP and related clinical characteristics. The predictive model based on PLR, NLR, CRP and related clinical factors has high predictive value, and can provide a basis for clinical decision-making. 

Key words: stomach neoplasms, peritoneal metastasis, C-reactive protein