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Increased cyclooxygenase-2 expression in large flat colorectal tumors (laterally spreading tumors)
Kentaro Yamashita1, Yoshiaki Arimura, Haruo Shimizu
1First Department of Internal Medicine, Sapporo Medical University, Sapporo, Japan.
Background:
Little is known about the molecular biological features of large flat tumors or laterally spreading tumors (LSTs) of the colon and rectum.
Methods:
The cyclooxygenase (COX)-2 protein expression level of LSTs was assessed immunohistochemically and compared with that of exophytic colorectal tumors. COX-2 expression in the dysplastic epithelial cells and the interstitial cells was evaluated independently.
Results:
Sixty-five LSTs and 65 exophytic tumors were randomly selected from the archives, and 61 and 59, respectively, were successfully analyzed. LSTs showed significantly more intense COX-2 protein expression in the dysplastic epithelial cells than the exophytic tumors ( P > 0.0001). COX-2-positive interstitial cells were also observed more frequently in LSTs than in the exophytic tumors ( P = 0.015).
Conclusions:
Overexpression of COX-2 protein may play a crucial role in the tumorigenesis of colorectal LSTs. Chemoprevention, using nonsteroidal anti-inflammatory drugs (NSAIDs) or selective COX-2 inhibitors may be effective for treating this unique neoplasm, which sometimes defies endoscopic treatment.