Estrogen and progesterone receptors in breast cancer. Immunohistochemical assay on scraping material.

In order to demonstrate the reliability of immunocytochemical results on cytologic specimens for receptor analysis, the expression of estrogen and progesterone receptors was investigated using immunohistochemistry on frozen sections and on scraping material from the same samples of 50 breast carcinomas. The level of agreement between the two procedures was evaluated by the kappa statistic, as was that between each immunohistochemical procedure and the dextran-coated-charcoal assay since the latter is still the assay employed most frequently for steroid receptor determination and is used for official reports. Statistical results revealed very good agreement regarding the estrogen receptor analysis, with kappa values of .910 and .952 for the comparison of the dextran-coated-charcoal assay with immunocytochemistry on frozen sections and on scrapes, respectively, and .950 for the comparison between the two immunocytochemical procedures. As to progesterone receptors, the kappa values were .795 and .712 for the comparison between the biochemical and immunocytochemical results and .915 for agreement evaluation between the two immunocytochemical procedures. The study showed that the scraping procedure is a valuable tool for the immunocytochemical assessment of steroid receptors in small mammary tumors; it yields representative cellular samples, thus permitting the investigation of heterogeneously distributed substances in tissues.