Discordant effect of aspirin and indomethacin on intestinal tumor burden in Apc(Min/+)mice.

Epidemiologic and animal studies indicate that sustained use of non-steroidal anti-inflammatory drugs (NSAIDs) have a chemopreventive effect against the incidence of colorectal neoplasia and subsequent mortality. We previously demonstrated that sulindac significantly reduces intestinal tumor load in Apc(Min/+)mice and the tumor regression was not necessarily correlated with prostaglandin biosynthesis. In the present study, we further investigate the relationship of NSAID treatment and tumorigenesis in the Apc(Min/+)mouse model. We demonstrate that indomethacin (9 ppm) is a very potent chemopreventive agent, reducing tumor load by 85% and significantly inhibiting basal and ex vivo prostaglandin formation (P< 0.006 and P< 0.0001, respectively). Aspirin (400 ppm) has a similar impact on reducing prostaglandin levels, but in contrast to indomethacin, is uneffective in reducing the tumor load. The data indicate a discordance between the impact of different NSAIDs on tumorigenesis in Apc(Min/+)mice. Copyright 2000 Harcourt Publishers Ltd.