AROMATIC INFLUENCES ON THE YIELDS OF MAMMARY CANCERS FOLLOWING ADMINISTRATION OF 7,12-DIMETHYLBENZ( a )ANTHRACENE

Abstract

By definition, an effective amount of 7,12-dimethylbenz(a)anthracene is that quantity which induces mammary cancer in every rat but is not lethal to any one. Effective amounts were investigated over a threefold range of dosage with respect to the yield of cancers. By single injection the largest quantity evoked the largest number of cancers. But equal fractions of this largest amount given at intervals of 3 days called forth more cancers than did the total amount injected on one occasion. Induction of mammary cancer was inhibited when any of 6 aromatics was fed repeatedly during a period of time that overlapped multiple injections of optimal amounts of 7,12-DMBA which, in unprotected controls, rapidly gave rise to large numbers of tumors. Tumor prophylaxis by protective aromatics consisted of (a) decreased yield of cancers, (b) delay in their appearance, and (c) complete suppression in a proportion of the protected animals. Ovarian function was not altered significantly by the experimental procedures. Prevention of hydrocarbon-induced apoplexy in the rat is a useful preliminary screen for compounds which suppress aromatic-induced cancer in the rat.