Influence of rofecoxib on experimental colonic carcinogenesis in rats

Aim: to investigate the effect of a selective cyclooxigenase-2 (COX-2) inhibitor, rofecoxib, in the prevalence of experimental colon tumors in rats. Experimental design: experimental study with 35 male Sprague-Dawley rats, divided into four groups: a) control group without experimental manipulation (n = 5); b) pharmacological carcinogenesis with 1-2 dimethylhydrazine dihydrocloride (n = 10); c) pharmacological carcinogenesis and addition of acetylsalicylic acid (AAS) (n = 10); and d) carcinogenesis and addition of rofecoxib (n = 10). Carcinogenesis was induced with 1-2 dimethylhydrazine at a weekly dose of 25 mg/kg for 18 weeks. Colon tumors were isolated at 20 weeks. Antiinflammatory agents were given at a dose of AAS 30 mg/kg and rofecoxib at 3 mg/kg. Results: the percentage of colonic tumors was significantly reduced in the rofecoxib group. This result was found for all tumors and for the malignant lesions, adenocarcinomas. Conclusions: rofecoxib, a selective COX-2 inhibitor, reduced the percentage of drug-induced neoplastic glandular tissue in rats.