Chemoprevention of tongue carcinogenesis in rats.

The inhibitory effects of vitamin A, selenium, butylated hydroxytoluene, and their combinations on tongue carcinogenesis induced by 4-nitroquinoline 1-oxide were examined in Sprague-Dawley rats. After 4 months of administration of 4-nitroquinoline 1-oxide, a wide range of lesions from hyperplasia to early invasive carcinoma was seen. The lesions were fewer and the carcinomas were less advanced in the rats given preventive treatment. The chemopreventive effect of vitamin A plus butylated hydroxytoluene was most effective. After 7 months of 4-nitroquinoline 1-oxide administration, the incidence, the macroscopic diameter, and the microscopic depth of invasion among carcinomas were smaller in the chemopreventive groups than in the nonchemopreventive group. We conclude that vitamin A, selenium, and butylated hydroxytoluene inhibit tongue carcinogenesis induced by 4-nitroquinoline 1-oxide in rats. The inhibitory effect of combined chemopreventives is not always superior to that of each chemopreventive agent used alone.