High COX-2 expression was seen in about 56.6% of well-differentiated carcinomas, 66.6% of moderately differentiated carcinomas, and 100% of poorly differentiated carcinomas. The depth of invasion (p = 0.021), tumor stage (p = 0.05), frequency of lymph node metastasis, and degree of differentiation were all correlated with COX-2 overexpression. The gene discussed is PTGS2; the disease is carcinoma.