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. tissue, 2 were borderline, and 14 did not contain any receptor. The proportion of positive results and the range of concentrations were found to be somewhat higher in postmenopausal than in premenopausal patients. Despite detailed examination, no histological feature was found which could explain the variation in receptor concentration; neither could it be accounted for by differences in the cellularity of the biopsies. Of the 41 benign breast biopsies examined only 3 contained any high-affinity oestradiol receptor and in these the concentration was very low, ranging from 0·3-0·6 × 10(-15) moles/mg. tissue. The receptor has not been detected in normal breast tissue. The relationship between the presence of oestrogen receptors and hormone responsiveness in tumours is discussed.