Induction of Rat Mammary Cancers by Cancer Chemotherapeutic Agents

Abstract

HUGGINS et al.¹ demonstrated that multiple mammary adenocarcinomas could be induced rapidly and invariably in female rats of the Sprague–Dawley strain by gastric instillation of 3-methylcholanthrene. Later, 7,12-di-methylbenz(a)anthracene was found to induce the same cancer². Shellabarger et al.³ induced similar mammary cancers in rats by sub-lethal whole-body γ-irradiation. Recently, Huggins and Fukunishi⁴ noted that mammary carcinomas elicited either by X-irradiation or by 7,12-dimethylbenz(a)anthracene had similar enzyme constitutions and hormone-dependency. Huggins and Yang⁵ have postulated that both radiation and polynuclear aromatic hydrocarbons exert their oncogenic effect by selective changes in the nucleic acids of mammary cells. In an experiment described here, it was noted that mammary cancers can arise also in rats receiving anti-cancer drugs, including biological alkylating agents. Although the biological alkylating agents have been shown to induce cancers in rats, these have usually been sarcomas arising at the site of a subcutaneous injection⁶.