Cyclooxygenase-2 Expression is Associated with Increased Size in Human Sporadic Colorectal Adenomas

Abstract

Background: Cyclooxygenase-2 (COX-2) has been implicated in colorectal carcinogenesis but its role is not completely defined. Materials and Methods: The expression of COX-2 was evaluated in 68 paraffin-embedded sporadic colorectal adenomas by immunohistochemistry. Associations between COX-2 expression and the clinicopathological characteristics of the adenomas were studied by contingency tables and the Chi-square test. Results: Cytoplasmic staining for COX-2 protein was present in epithelial cells of 62 out of the 68 adenomas. COX-2 expression was not associated with age or gender. Furthermore, no significant correlations were found between the expression of the protein and histology (tubular vs tubulovillous), localization (proximal vs distal) or morphology (sessil vs pedunculated) of the adenomas. Both stromal and epithelial COX-2 expressions were higher in larger (>4 mm) compared with smaller (≤4 mm) adenomas (p=0.037 and p=0.024). Conclusion: These data support the hypothesis that the expression of COX-2 may occur as a general phenomenon in colorectal adenomas. A size-dependent increase of COX-2 expression might be involved in colorectal carcinogenesis.