Protection by Testosterone from Fluorouracil-induced Toxicity without Loss of Anticancer Activity against Autochthonous Murine Breast Tumors¹

The present paper describes the specific amelioration of 5-flourouracil (FUra)-induced host toxicity (manifest in body weight loss, leukopenia, and mortality) by testosterone in the spontaneous, autochthonous CD8F₁ (BALB/c × DBA/8F₁) murine breast tumor model. Administration of testosterone did not affect the growth rate of these hormone-independent tumors, and, most importantly the antitumor activity of FUra was not reduced in testosterone-treated mice. Therefore, the net result of treatment with the combination of FUra and testosterone was an increase in the selective antitumor specificity of FUra.