A simple method for the determination of oestrogen receptor concentrations in breast tumours and other tissues.

A simple method for the determination of oestrogen receptor activity in breast tumours and other tissues is described. By competition between radioactive and non-radioactive oestradiol-17beta for binding to a tissue extract prepared with centrifugation at low speed, the presence or absence of receptors is decided from the unmanipulated data. The concentration of receptors (P0) and dissociation constant of binding (Kd) are calculated by Scatchard analysis. In two relatively homogeneous tissues, assay precision was of the order of 16% for receptor concentration and 21-33% for the dissociation constant of binding: in heterogeneous breast tumors, much poorer precision can be expected. Sensitivity determined empirically is approximately 0.1 fmol/mg tissue. The method has been applied to the determination of receptor concentrations in human breast cancers, benign breast tumours, non-malignant breast, gynaecomastic breast, and in various tissues of the rat. Receptor activity was detected in 70% of the human breast cancers examined, and in lower amounts, in 21% of the benign human breast tissues. Activity was also detected in rat uterus and mammary gland, and in low amounts in 82% of the rat mammary tumours analysed. Dissociation constant of binding was generally of the order of 0.5 x 10(-10) M. The advantages of the method are discussed.