Cyclooxygenase-2 overexpression is related to polypoid growth and K-ras gene mutation in T1 colorectal carcinomas

PURPOSE: Cyclooxygenase-2 is thought to play a role in the development of intestinal tumors and levels are elevated in approximately 80 to 90 percent of human colorectal carcinomas. To clarify the role that cyclooxygenase-2 plays in the development of colorectal carcinoma, we studied the relationship between cyclooxygenase-2 expression and tumor morphology and that between cyclooxygenase-2 expression and K-ras mutation. METHODS: We classified 48 T1 colorectal carcinomas as polypoid or nonpolypoid and analyzed the clinicopathologic features. The expression of cyclooxygenase-2 was determined immunohistochemically, and nested polymerase chain reaction-restriction fragment length polymorphism detected a K-ras codon 12 mutation. RESULTS: Cyclooxygenase-2 expression was higher in polypoid carcinomas than in nonpolypoid carcinomas (P < 0.001). The K-ras codon 12 mutation was associated with higher levels of cyclooxygenase-2 expression compared with carcinomas without this mutation (P = 0.028). CONCLUSIONS: Polypoid growth and K-ras gene mutation are both associated with increased levels of cyclooxygenase-2 expression in T1 tumors.