Hormonal control of human breast cancer cell lines.

The most widely studied steroid hormone responsive cancers are those of the prostate, endometrium and mammary endothelium and the leukaemias. Steroids may in some cases be involved in tumour initiation, and they induce critical events in the malignant 'progression' of these cancers once they develop (after exposure to carcinogens, for example). This paper focuses on the role of the oestrogen receptor as a trigger of cellular growth and invasiveness and as modulator of growth factor secretion in human breast cancer. Growth factor secretion may be a common final pathway of diverse tumorigenic stimuli in a variety of cancers. The finding of external growth control mechanisms suggests possible new ways of therapeutic intervention in breast cancer.