Pituitary role in the estrogen dependency of experimental mammary cancer.

Mammary tumors were induced in 50-day-old albino Sprague-Dawley rats by a single feeding of 20 mg. of 7,[email protected][a]anthracene. Adrenalectomy-ovariec tomy and hypophysectomy performed within 10-20 days after tumors were first de tected resulted in tumor regression in all the animals. Estrogen administration re activated tumor growth after adrenalectomy-ovariectomy but not after hypophy sectomy. The estrogen unresponsiveness of tumors in hypophysectomized animals was not modified by thyroid and cortisone replacement therapy. These results indicate that the estrogen stimulation of this tumor is dependent upon the presence of the pituitary gland.