Oestradiol receptors in non-neoplastic gynaecomastic tissue of phenotypic males.

Cytoplasmic oestradiol receptors have been reported in breast tumor tissue but not in the uninvolved tissue from the same patients. Since gynaecomastic tissue is highly predisposed to neoplastic transformation, such receptors were looked for in this tissue from 13 phenotypic males of whom 6 had Klinefelter's syndrome. High affinity saturable binding (Kd approximately 10(-10) M) of 3H-oestradiol-17 beta was found in the breast tissue from 12 of these patients by gel elution and dextran-coated charcoal techniques. The concentration of binding sites were found to range from 16 to 359 fmol/mg cytosol protein. Previous studies by the present authors showing steroid aromatising capacity and the present finding of specific oestradiol receptors in a 'high-risk tissue' in the absence of any histologically detectable neoplasms might be relevant in elucidating the natural history of breast cancer in such individuals.