Cyclooxygenase-2 expression in hepatocellular carcinoma, cirrhosis and chronic hepatitis in the United States

Aberrant expression of cyclooxygenase-2 in hepatocellular carcinoma was described in Asia. Using immunohistochemistry, we studied the expression of cyclooxygenase-2 in hepatocellular carcinoma, chronic hepatitis, and cirrhosis in a US institution. A staining score of 0-5 representing the sum of an intensity score and a distribution score was used. The mean scores were 2.2 +/- 1.60 for chronic hepatitis, 4.37 +/- 1.15 for cirrhosis, and 4.76 +/- 0.54 for hepatocellular carcinoma. We found a significant difference in mean staining scores between chronic hepatitis and cirrhosis (p < 0.0001), as well as between chronic hepatitis and hepatocellular carcinoma (p < 0.0001). Fibrosis correlated with cyclooxygenase-2 staining score (r=0.65). In conclusion: (1) Cyclooxygenase-2 expression is higher in cirrhosis and hepatocellular carcinoma when compared to chronic hepatitis. (2) Cyclooxygenase-2 expression correlates with the stage of fibrosis. (3) These results imply that in chronic hepatitis and possibly in cirrhosis, hepatocarcinogenesis may be a cyclooxygenase-2 dependent mechanism.