Polyethylene glycol 8000 and colon carcinogenesis: Inhibition in the F344 rat, promotion in the Min mouse

It has recently been reported that 5% polyethylene glycol 8000 (PEG 8000; M -r 8000) in the diet markedly inhibits the development of colonic tumors in carcinogen-treated rats. To assess the possible use of this agent as a pre ventive or treatment agent for patients with familial adenomatous polyposis , we determined the effect of PEG 8000 on spontaneous carcinogenesis in the Min mouse. PEG at a 5% concentration in the diet of Min mice did not affec t the number of small intestinal or cecal tumors but did increase the numbe r of colon tumors and the number of animals with colonic tumors (2 of 18 ve rsus 12 of 22 animals; P < 0.001). Although the chemopreventive effect of P EG 8000 in rats is remarkable, we suggest a cautious approach in long-term testing of PEG as a chemopreventive agent for subjects at risk for colonic neoplasia.