Induction of skin and thyroid tumors in male rats by N-methyl-N-nitrosourea after sequential treatment with cyproterone acetate and testosterone propionate : effects of castration, rat strain and time of carcinogen injection

The purpose of this study was to determine the carcinogenic effect in male rats of a single i.v. injection of N-methyl-N-nitrosourea (MNU) after sequential treatment with cyproterone acetate (for 21 days) and testosterone propionate (for 3 days). This treatment has previously been shown to induce carcinoma of the prostate and other male accessory sex glands. A wide spectrum of non-melanoma skin tumors was found in 38-48% of Wistar (Cpb:WU) rats given this sequential treatment, but only in 5% of rats that received only MNU