Effects of p-methoxyphenol and diet on carcinogen-induced neoplasia of the mouse forestomach.

Previously, p-methoxyphenol fed in the diet was found to be the most potent inhibitor of benzo(a)pyrene-induced neoplasia of the mouse forestomach of 18 phenols investigated. In the present study, the effects of p-methoxyphenol on the direct-acting carcinogen, beta-propiolactone (BPL), were determined. p-Methoxyphenol administered at 1 or 4 hr prior to BPL or fed in the diet markedly inhibited BPL-induced neoplasia of the mouse forestomach. Of 10 phenols tested by p.o. intubation, it was the only one that exerted a significant inhibitory activity. Thus far, p-methoxyphenol appears to be an effective inhibitor only when given prior to carcinogen administration. During these studies, it was found that the nature of the diet markedly altered the neoplastic response of the mouse forestomach to BPL but not to benzo(a)pyrene.