Experiments on the influence of an aromatic retinoid on the chemical carcinogenesis induced by N-nitroso-methyl benzylamine in rats.

The effect of simultaneous administration of the aromatic retinoid ethyl all-trans-9-(4-methoxy-2,3,6-trimethylphenyl)-3,7-dimethyl-2,4,6,8-nonatetraenoate (Ro 10-9359) on the carcinogenicity of N-nitrosomethyl benzylamine (NMBA) in the esophagus of Sprague-Dawley rats was investigated. Two doses of the retinoid, namely 30 or 60 mg/kg of diet, were tested. The retinoid induced marked toxicity including a depression of growth and pathological fractures at the high dose. In spite of the toxic effects encountered, the only statistically significant result recorded was a slight increase in the latent period of induction of the esophageal tumors. It is concluded that this study did not demonstrate any inhibitory or other effects of the retinoid on the induction of esophageal tumors by NMBA.