Cyclooxygenase-2 immunoreactivity in depressed-type colorectal adenomas and cancers.

In order to clarify the relationship of the cyclooxygenase-2 immunoreactivity and the progression of depressed-type colorectal adenomas and cancers, we examined cyclooxygenase-2 expression in depressed-type colorectal adenomas and cancers. Immunohistochemical staining was performed by the streptavidin-biotin method. Among 100 adenomas, depressed-type were found in 15, cyclooxygenase-2 expression was not detected in depressed-types, and lesion size in depressed-types did not differ from that in others. Among 100 submucosal invasive cancers, depressed-type were found in 14, cyclooxygenase-2 expression was not detected in depressed-types, and lesion size in tumor with depressed-type did not differ from that in others. Among 100 cancers invading the muscularis propria, depressed-types in 15, cyclooxygenase-2 expression was not detected in depressed-types; these were significantly smaller lesions than those in others (p<0.05). Our results suggest that depressed-type cancers do not result from cyclooxygenase-2 expression.