Effect of Hypothyroidism on Induction of Mammary Tumors in Rats by 7,12-Dimethylbenz[<italic>a</italic>]anthracene<xref ref-type="fn" rid="FN2">2</xref>

Abstract

In female Sprague-Dawley rats, the incidence of palpable nodules of the mammary gland after intravenous administration of 7,12-dimethylbenz[a]anthracene was decreased by hypothyroidism induced with antithyroidal drugs. Methimazole completely suppressed tumor induction during an observation period sufficient for a 100% tumor incidence with the carcinogen alone. In our experiments, the tumor-inhibitory effect of decreased food intake cannot be ruled out.