Oestrogen receptors in relation to human breast cancer.

Work leading to the concept of hormone responsiveness of human breast cancer and current views of the mode of action of oestrogens in target tissues are reviewed. Results of oestrogen receptor assays are considered in relation to clinical response to tumours to endocrine therapy and difficulties encountered in the interpretation of receptor determinations are discussed. Recent work on the distribution of different forms of the oestrogen receptors in human tumours and their relation to clinical response may lead to better selection of patients for endocrine therapy. Results of receptor assays in male patients with breast cancer, in benign breast tumours and in malignant tumours at sites other than breast are reviewed, and work on receptors for hormones other than oestrogens is discussed briefly. Further work is needed on the integrity of the receptor mechanism in tumour cells and on the effects of hormone treatment. Methods for the separation and estimation of oestrogen receptors in human tumour tissue are reviewed and discussed. Errors arising during collection, storage and analysis are considered. Different ways of calculating and expressing results of these assays are mentioned. It is suggested that more accurate determinations of oestrogen receptors may lead to better discrimination between hormone responsive and unresponsive human breast tumours.