Abstract
Summary
1. X-rays (50r) and mammotropic hormones (administered in form of isologous functional mammotropic pituitary tumor grafts) alone produced no mammary tumors in female W/Fu rats within 7 months of treatment. In contrast, 53% rats treated with both, developed mammray tumors. As with chemical carcinogen-induced tumors, administration of mammotropic hormones restored inhibition of mammary tumor development by ovariectomy. 2. Most mammary tumors induced by radiation plus mammotropic hormones were adenocarcinomas; a few were fibroadenomas. 3. Three induced tumors tested were found to be highly mammotropic hormone responsive: they did not grow in males and grew in females uniformly only when stimulated with mammotropic hormones. 4. Grafted fibroadenoma cells remained latent in many rats until administered mammotropic hormones brought about their rapid growth. Administration of this hormone could be delayed as long as 7 1/2 months. 5. It is concluded that radiations bring about an irreversible modification of some cells, depending on severity of the dose; mammotropic hormones are not carcinogens but, as promoters of mammary epithelium, promote carcinogenesis and growth of some tumors.
Get full access to this article
View all access options for this article.