Sex Steroid Hormones and Tumors in Domestic Animals

Abstract

Sex steroid hormones play a role in the development and control of animal tumours, particularly in those arising in their target organs. Due to their incidence and prevalence, mammary tumours of female dogs and cats are among the most frequently studied with focus on the role of ovarian oestrogen and progesterone. In these tumours, sex steroid hormones have been shown to act during the three steps of the carcinogenesis cascade: initiation, promotion and progression. Experimental data have shown the mutagenic effect of oestrogens [1] while epidemiologic and clinical studies highlighted the role of ovarian hormones as promoters on mammary tumours in both the dog and the cat [2-9]. Finally, oestrogens and progesterone further act during tumour progression. Their role in the last two steps of carcinogenesis makes it possible to control the evolution of the disease