Chemoprevention of mammary tumorigenesis by a combined regimen of selenium and vitamin A.

Mammary tumorigenesis induced in rats by 7,12-dimethylbenz[a]anthracene was markedly suppressed by combined dietary supplementation with sodium selenite and retinyl acetate; final tumor yield was reduced to 8% of control as compared with 51% and 36%, respectively, for selenium and retinyl acetate alone. A continuous intake of both agents was necessary to sustain the chemopreventive effect.