Expression Of Cyclooxygenase-2 In Gastric Cancer And Its Relationship To Hematogenous Metastsis And Long-term Prognosis

Epidmiologic studies show that nonsteroidal anti-inflammatory drugs(NSAID) can reduce the incidence rate and mortality from digestive tract carcinomas ,including esophageal,gastric,colon,and rectal lesion. Abnormal expression of Cyclooxygenase-2 (COX-2) has been proposed to correlate with the development of gastric cancer.We attempted to determine the expression of COX-2 in gastric cancer,the relationship between expression of COX-2 and the clinicopathological feature of cancer, to evaluate its prognostic value.Materials and MethodsThe tissue specimens examined for COX-2 mRNA expression were taken from 47 gastric cancer patients who underwentresection.Expression of COX-2 mRNA were examined in gastric cancer and its paired substantial normal tissue by semi-quantitative RT-PCR. Expression of COX-2 protein were examined in gastric cancer by immunohistochemistry(two step Envision method), we investigated the relationship between COX-2 protein expression and prognosis in 195 gastric cancer patients. The association of the COX-2 expression with clinicopathological factors (histologic type,depth of invision lymphatic invasion,venous invasion,lymph node metastasis, peritoneal metastasis,live metastasis,and hematogenous metastasis) was assessed by cross-tabulation,and the signifance of differences was determined by the chi-square test.Life table analysis was performed using the Kaplan -Meier technique.A multivariate Logistic regression analysis was done to evaluate the risk factor for hematogenous metastasis.ResultsThe expression of COX-2 mRNA in gastric cancer was significantly higher than that of non-cancerous mucosa(p<0.001). COX-2 immunoreactivity was detected in 58% (113 of 195) gastric cancer , COX-2 protein was expressed statistically more frequently and at a higher level in differentiated,adenocarcinoma than in diffuse type carcinoma ,the expression of COX-2 was more frequently in gastric cancer withlymphnode metastasis and venous invasion,liver metastasis,hematogenous metastasis than in those without metastasis. There was no statistically significant correlation between COX-2 immunoreactivity and depth of invasion ,lymphatic invasion ,peritoneal metastsis and UICC TNM stage.The COX-2 positive cancers were more frequently associated with hematogenous metastasis.however,there was no significant correlation between COX-2 immunoreactivity and prognosis among cases.ConclusionsThere is high expression of COX-2 mRNA and protein in gastric cancer , indicating its involvement in the development of gastric cancer, COX-2 may play an important role in hematogenous metastasis.