Oestradiol receptors in carcinoma and benign disease of the breast: an in vitro assay.

An assay is described for measuring the concentration of specific, high-affinity oestradiol receptors in the cell supernatant fraction of breast tumour biopsies. The method has been applied to biopsies from 94 patients with malignant and benign diseases of the breast. Of the 53 biopsies classified as carcinomas, 37 contained high-affinity oestradiol receptors in concentrations ranging from 0·3-22·6 × 10(-15) moles/mg.