A total of 270 gastric cancer patients who underwent radical gastrectomy were enrolled in this study， and the positive expression rates of MMP-9 and TIMP-1 in cancer tissue of the patients were detected by immunohistochemistry method. Pearson χ² or Fisher’s exact test was used to assess the distribution of MMP-9 and TIMP-1 positive expressions in the gastric cancer patients with different clinicopathological parameters. Survival curves were plotted using Kaplan-Meier method and the differences were assessed by Log-rank test. Multivariate Cox regression model was conducted to analyze the relationships between the expressions of MMP-9 and TIMP-1 and the prognosis of the gastric cancer patients underwent radical gastrectomy.

Among the 270 gastric cancer patients， MMP-9 and TIMP-1 were expressed in cytoplasm or cell membrane of tumor cells， and the positive expression rates of MMP-9 and TIMP-1 were 30.4% and 26.3%， respectively. No correlations between the co-expression of MMP-9， TIMP-1 and the age，gender，tumor size，tumor type，histological type，chemotherapy after operation，and TNM stage of the patients were identified. The results of Cox regression model showed that co-expression of MMP-9 and TIMP-1， postoperative chemotherapy and TNM stage were the significant independent factors for the prognosis of the gastric cancer patients. The gastric cancer patients with MMP-9 positive expression showed the better survival， and among the patients withMMP-9 negative expression， the risk of death in the patients with TIMP-1 positive expression was increased， which indicated the worse prognosis（MMP-9⁺/TIMP-1^+/－vs MMP-9^－/TIMP-1⁺：HR=0.537， 95% CI： 0.338－0.851，P=0.008）. Furthermore， compared with the patients with postoperative chemotherapy and TNM stage Ⅰ/Ⅱ， the patients with no-postoperative chemotherapy and TNM stage Ⅲ had higher risk of death and worse prognosis（HR=1.873，95% CI： 1.334－2.631，P<0.001； HR=2.301， 95% CI： 1.656－3.197， P<0.001）.In the subgroup analysis， among the gastric cancer patients with TNM stage Ⅰ/Ⅱ， postoperative chemotherapy or no signet-ring cell cancers， the risk of death in MMP-9⁺ group was decreased compared with MMP-9^－/TIMP-1⁺ subgroup （P<0.05），which indicated the better prognosis.

Co-expression of MMP-9 and TIMP-1 could serve as an independent prognostic predictor in the gastric cancer patients underwent radical gastrectomy； No postoperative chemotherapy and TNM stage Ⅲ are the risk factors for the prognosis of gastric cancer patients underwent radical gastrectomy.