Immunocytochemical detection of estrogen receptors by staining with monoclonal antibodies on cytologic specimens of human breast cancer.

A study was undertaken to test the possibility of determining the estrogen receptor (ER) content in human breast cancers by staining with commercial specific monoclonal antibodies (MAbs) on cytologic specimens (touch imprints and fine needle aspirates). The aspirates were suspended in a cell culture medium and cytocentrifuged onto slides to preserve their morphologic characteristics and to allow a proper immunocytochemical staining for ERs. MAb staining for ER was also performed on the respective surgical samples. The staining of cytologic samples for ER showed 100% specificity and 95% sensitivity in comparison to the staining of the histologic samples. Moreover, comparison of the percentage of stained cells in the cytologic specimens to the ER content in the respective surgical specimens, as assayed by the dextran-coated charcoal method, showed the MAb staining of cytologic samples to have 94% specificity and 100% sensitivity. These results support the reliability of MAb staining for ERs in cytologic samples and suggest that it could be the assay of choice in particular clinical settings in the evaluation of primary and recurrent breast cancers.