Polyethylene-glycol, a potent suppressor of azoxymethane-induced colonic aberrant crypt foci in rats.

Bulking fibers and high water intake may decrease colon carcinogenesis in rats, and the risk of colorectal cancer in humans. We speculated that a non-fermented polymer, polyethylene-glycol (PEG) 8000, which increases stool moisture, might protect rats against colon carcinogenesis. Thirty female F344 rats were given a single injection of azoxymethane (20 mg/kg), and 7 days later randomized to AIN76 diets containing PEG (to provide 3 g/kg body wt/day), or no PEG (control). Diets were given ad libitum for 105 days, then colon carcinogenesis was assessed by the aberrant crypt foci (ACF) test. ACF were scored blindly by a single observer. Dietary feeding of PEG almost suppressed ACF larger than one crypt, and strikingly decreased the total number of ACF per rat. PEG-fed rats had 100 times less large ACF than controls (0.8 and 83 respectively, P = 0.00001). PEG-fed rats had 20 times less total ACF than control (six and 107 ACF/rat, respectively; P < 0.0001). Two treated rats had no detectable ACF. PEG is 10 times more potent than other chemopreventive agents in this model. Since PEG is generally recognized as safe, its cancer-preventive features could be tested in humans.