Cyclooxygenase-2 expression correlates with tumor neovascularization and prognosis in human colorectal carcinoma patients.

The role of cyclooxygenase-2 (COX-2) in tumor neovascularization of human colorectal carcinoma is yet to be delineated. One hundred colorectal carcinoma specimens were evaluated for COX-2 expression and CD34-stained microvessel density (MVD) by immunohistochemical methods. The relationships between COX-2 expression and clinicopathological feature of the patients, MVD, and survival time were analyzed. Increased COX-2 expression was significantly correlated with pathologically unfavorable findings such as tumor size (> 3.0 cm), tumor differentiation (poor, moderate > well differentiated), number of metastatic lymph nodes (24), and Dukes' stage (Dukes' B, C, and D). Larger number of microvessels congregated around the COX-2-expressing area, and the Spearman rank correlation test showed a strong correlation between COX-2 expression and tumor MVD (P < 0.0001). Patients with COX-2-positive tumors had a significantly (P = 0.037, by log-rank test) shorter survival time than those with negative tumors did. In the multivariate analysis, however, only Dukes' stage and number of metastatic lymph nodes remained as independent prognostic factors. Augmented tumor neovascularization may be one of the several effects of COX-2 responsible for poor prognosis in human colorectal carcinoma patients.