Expression of cyclooxygenase-2 in colonic polyps

INTRODUCTION: Limited data is available regarding the relationships between cyclooxygenase-2 (COX-2) and colorectal cancer formation. OBJECTIVES: The aim of the study was to investigate cyclooxygenase-2 (COX-2) expression in histologically diverse colonic polyps, to determine the association between the expression of this enzyme and selected patho logical and clinical characteristics of polyps, and to establish the location of cells with high COX-2 expression within the polyp. PATIENTS AND METHODS: We examined 212 colonic polyps from 175 patients. Immunohistochemical staining with monoclonal anti-COX-2 antibodies was performed. RESULTS: Statistically significant differences associated with high COX-2 expression were found: in adenomas vs. other polyps (P <0.001), in adenomas with high-grade dysplasia (P <0.000 001), and in polyps of the cecum (P <0.02). Statistically significant differences in COX-2 were also associated with polyp size (P <0.000 001). Cells with high COX-2 expression were usually located in the epithelial layer (P = 0.01). No significant associations were found between high COX-2 expression and the age and sex of patients or the total number of polyps. CONCLUSIONS: We demonstrated that high COX-2 expression is associated with typical risk factors for malignant transformation of colonic polyps. The results suggest the possible role of COX-2 in the early stages of colon carcinogenesis.