Many studies have shown that COX-2 is overexpressed in some pre-cancerous lesions and cancer types, including kidney, uterus, bowel, and bladder cancer.14,36,77 The contribution of COX-2 to the development of colon cancers supports a role in the control of cell growth that is apart from the COX-1 isoform.3 In human gastric adenocarcinoma tissues, COX-2 mRNA levels were increased compared to normal samples in gastric mucosal tissue, but COX-1 mRNA levels were not elevated in carcinoma.9 The prolonged increase of COX-2 expression following colitis increases the sensitivity to colon cancer.28 This evidence concerns the gene PTGS2 and urinary bladder cancer.