Expression of Cyclooxygenase-2 and Tumor Microvessel Density in Colorectal Cancer.

PURPOSE The increased expression of cyclooxygenase (COX)-2 has been implicated in the development and progression of human cancer. This study investigated the COX-2 expression in colorectal cancer, and its relationships with tumor angiogenesis and the clinicopathological factors. MATERIALS AND METHODS The expression of the COX-2 protein and microvessel density were evaluated, using immunohistochemical methods, in 21 normal colonic mucosa and 190 human colorectal carcinomas. Correlations between COX-2 expression and microvessel density, as well as various clinicopathological factors, were studied in colorectal carcinomas. RESULTS The COX-2 protein expression in epithelial cells was increased in 169 of the 190 adenocarcinoma cases (88.9%), but in only 1 of the 21 (4.8%) normal mucosa cases. The COX-2 expression was significantly increased in the differentiated compared with the undifferentiated colorectal carcinomas (p<0.05), and significantly correlated with the depth of invasion and microvessel density (p<0.05). Rectal cancers had more COX-2 positive cases than the colon cancers (p<0.05). However, there were no significant differences in the tumor size and the presence of lymphatic or vascular invasion. CONCLUSION The overexpression of cyclooxygenase-2 in colorectal carcinomas seems to play a role in the invasion and angiogenesis of the tumors, so may be a useful marker of the prognosis. The prominent expression was also demonstrated in differentiated colorectal cancers.