Immunohistologic detection of estrogen receptors in paraffin-embedded breast cancers: correlation with cytosol measurements.

Paraffin-embedded sections of 76 human breast tissue specimens were analyzed for estrogen receptors (ER) and endogenous bound estrogen (ER-E). Preincubation of sections with polyestradiol phosphate was followed by stabilization of the complex with glutaraldehyde. The bound hormone was then visualized by the peroxidase-antiperoxidase (PAP) technique with antiestradiol as the primary antiserum. Normal breast tissue and benign proliferations were consistently positive for ER and ER-E. All specimens were examined for free and bound receptors in cytoplasm and nuclei. Among the carcinomas examined, a high correlation was found between the presence of ER by the PAP method and by the biochemical analysis of cytosol preparations. The PAP method, requiring no special preparation of surgical specimens, overcomes many of the disadvantages of the cytosol method and adds the advantage of independent evaluation of nuclear and cytoplasmic estrogen binding sites.