A E Davis1, F Patterson. 1. Department of Gastroenterology, Prince of Wales Hospital, Sydney, NSW, Australia.
Abstract
BACKGROUND: Epidemiological studies in humans suggest that regular use of non-steroidal anti-inflammatory drugs (NSAIDS) especially aspirin significantly decreases the risk of developing colorectal cancer. AIMS: The purpose of this study was to investigate the effect of aspirin on colonic carcinogenesis using the dimethylhydrazine (DMH) colonic cancer model in rats. METHODS: Groups of animals were given daily doses of aspirin either 0, 5, 30 or 60 mg/kg for 18 weeks. Half of each group also received 18 x 30 mg/kg/wk injections of DMH. RESULTS: Aspirin at doses of 5, 30 or 60 mg/kg/dy had a progressive effect on the reduction of tumour numbers and the percentage of tumours greater or equal to 5 mm in diameter. Aspirin at doses of 30 and 60 mg/kg/dy significantly reduced tumour incidence. CONCLUSION: These findings support the epidemiological studies in humans. The rat DMH model would appear to be suitable for investigating the mechanism of action of aspirin in reducing colonic tumour formation.
BACKGROUND: Epidemiological studies in humans suggest that regular use of non-steroidal anti-inflammatory drugs (NSAIDS) especially aspirin significantly decreases the risk of developing colorectal cancer. AIMS: The purpose of this study was to investigate the effect of aspirin on colonic carcinogenesis using the dimethylhydrazine (DMH) colonic cancer model in rats. METHODS: Groups of animals were given daily doses of aspirin either 0, 5, 30 or 60 mg/kg for 18 weeks. Half of each group also received 18 x 30 mg/kg/wk injections of DMH. RESULTS:Aspirin at doses of 5, 30 or 60 mg/kg/dy had a progressive effect on the reduction of tumour numbers and the percentage of tumours greater or equal to 5 mm in diameter. Aspirin at doses of 30 and 60 mg/kg/dy significantly reduced tumour incidence. CONCLUSION: These findings support the epidemiological studies in humans. The ratDMH model would appear to be suitable for investigating the mechanism of action of aspirin in reducing colonic tumour formation.