Effects of retinoids in N-nitrosobis(2-oxopropyl)amine-treated hamsters.

The effect of feeding four synthetic retinoids was evaluated in carcinogen-treated hamsters. Syrian golden hamsters were injected with 20 mg/kg of N-nitrosobis(2-oxopropyl)amine (BOP) and then fed retinoid-supplemented diets for 39 weeks. All retinoid-treated groups grew more slowly than controls, and average survival was shorter in female retinoid-treated groups. A significant incidence of testicular atrophy was noted in male hamsters fed 2-hydroxyethylretinamide or 4-carboxyphenylretinamide. The incidence of pancreatic carcinomas was lower in 12 of 14 retinoid-fed groups than in the corresponding control groups, although the differences approached significance only in groups fed two of the retinoids--male hamsters fed N-4-propionyloxyphenylretinamide and those fed retinylidene dimedone. A low incidence of carcinoma in the control groups limits the conclusions that can be drawn from this study, but it is of note that there was no evidence of promotion.