Abstract: Abstract Objective: To investigate the clinicopathologic significance of peritoneal metastasis (PM) in gastric cancer. We tend to illuminate the mechanism of peritoneal metastasis by performing the immunohistochemical staining of HIF-1a、FAK and MMP-9. Method: 164 gastric cancer samples with detailed follow-up data were collected. Immunohistochemical staining of HIF-1a、FAK and MMP-9 were performed for all samples. Result: PM was observed in 41 of the 164 GAC patients, especially in diffuse-type gastric cancer (DGC) (P=0.019). The Kaplan-Meier survival analysis showed that the survival duration of the PM-positive group was significantly shorter than that of PM-negative group (P=0.000). Cox proportional hazards model indicated that the PM and TNM stage were independent predictors of poor prognosis for GAC. The immunohistochemical expression of HIF-1a、FAK and MMP-9 were all higher in the PM-positive group than in the PM-negative group (P<0.05 for all). Conclusion: PM is an unfavorable prognostic indictor for gastric cancer which was associated with infiltrating depth and TNM stage. DGC tend to have peritoneal metastasis easily. Hypoxia might play a role in the formation of PM in gastric cancer.

Key words: peritoneal metastasis, diffuse-type gastric cancer, intestinal-type gastric cancer, hypoxia-inducible factor-1a