Expression of cyclooxygenase-2 in gastric cancer and its relation to liver metastasis and long-term prognosis

AIM: To investigate the expression of cyclooxygenase-2(COX-2) in gastric cancer and its relation with the liver metastasis and prognosis.METHODS: Expression of COX-2 mRNA and protein was examined in gastric cancer and its paired substantial normal tissue by semi-quantitative reverse transcriptionpolymerase chain reaction and immunohistochemistry.The relation between COX-2 expression and prognosis was investigated in 195 cases.RESULTS: The expression of COX-2 mRNA in gastric cancer tissue was significantly higher than that in normal tissue in 47 cases (w= 792, P＜0.01). The COX-2 mRNA in pT3-4 tissue expressed higher than that in pT1-2tissue (w = 204, P＜0.05). The positive expression rate of COX-2 protein was 57.9% (113/195). The COX-2expression was significantly related to histological type,lymphnode metastasis, venous invasion and liver metastasis (P＜0.05). No relation was found between COX-2 expression and invasion depth, peritoneal metastasis and International Union against Cancer TNMstage. The multiple regression analysis showed that the COX-2 expression and venous invasion were obviously associated with liver metastasis (P＜0.05). However,there was no significant correlation between COX-2immunoreactivity and prognosis.CONCLUSION: COX-2 may play an important role in the development of gastric cancer, and the over-expression of COX-2 protein may be a high risk factor for liver metastasis.