Oestrogens, Beatson and endocrine therapy

Introduction Oestrogens are central to the control of proliferation of normal breast epithelial cells and of endocrineresponsive tumours derived from them. The beginnings of our understanding of the importance of ovarian oestrogens in breast cancer came from Schinzinger's (1889) suggestion that the ovaries may affect breast cancer growth and Beatson's (1896) courageous clinical experiment. This dramatic demonstration of the relationship between ovarian secretions and the breast led to a series of experiments in rodents, in cell lines and in the clinic over the past 100 years which have demonstrated the mechanism of the interaction (Table 1). During this period, extracts of ovaries were tested in rodents, followed by purification and later synthesis of oestrogens. Non-steroidal and steroidal inhibitors of oestrogen action and oestrogen synthesis were developed later. Further understanding of the importance of the ovaries came from experiments, initially in laboratory mice, and later in the laboratory rat.