[Cyclooxygenase-2 expression according to size and location of gastric and colorectal tubular adenomas].

Background/aims: Recent studies have shown that cyclooxygenase-2 (COX-2) may be involved in the process of invasion, growth and apoptosis in colorectal carcinoma and in the growth and tumorigenesis in familial adenomatous polyposis. This study was conducted to determine the significance of the expression of COX-2 in gastric and colorectal adenomas.

Methods: Forty-nine samples of gastric adenoma and fifty-seven samples of colorectal adenoma were obtained by endoscopic mucosal resection or polypectomy from 106 patients from January 2000 to July 2003. COX-2 expression was determined by immunohistochemistry. Correlation between COX-2 expression and several clinical factors were compared in each gastric and colorectal adenomas.

Results: The expression of COX-2 in epithelial cells was significantly higher in the group with large adenoma (>1 cm) compared with the group with small adenoma (< or =1 cm) in gastric (76.5% vs. 46.7%, p=0.04) and colorectal adenomas (75% vs. 41.5%, p=0.023). Moreover, increased COX-2 expression was shown in distal compared to proximal colorectal adenoma (64.3% vs. 37.9%, p=0.047).

Conclusions: COX-2 was expressed in a size-dependent manner in gastric and colorectal tubular adenomas. The expression of COX-2 was different according to the location of colorectal adenoma. The association of COX-2 expression with the size of adenoma may suggest that the role of COX-2 is not related to the early development of adenoma, but related to the progression of adenoma.