Inhibition of Carcinogen-induced Neoplasia by Sodium Cyanate, ferf-Butyl Isocyanate, and Benzyl Isothiocyanate Administered Subsequent to Carcinogen Exposure1

The effects of sodium cyanate, ferf-butyl isocyanate, and benzyl isothiocyanate on carcinogen-induced neoplasia were studied in experiments in which the test compound was fed starting 1 week following completion of carcinogen administra tions. Under these conditions, all three test compounds exerted an inhibitory effect on the occurrence of 7,12-dimethylbenz(a)anthracene-induced neoplasia of the breast of Sprague-Dawley rats. In a second experiment model, sodium cyanate inhibited the occurrence of 1,2-dimethylhydrazine-induced neoplasia of the large bowel of female CF-1 mice. Thus, a new group of compounds has been identified which has inhibitory capacities against neoplasia when given subsequent to carcinogen exposure.