Estrogen receptor analysis on biopsies and fine-needle aspirates from human breast carcinoma. Correlation of biochemical and immunohistochemical methods using monoclonal antireceptor antibodies.

Monoclonal antibodies against estrogen receptor (ER) were used for determination of ER status immunocytochemically in histologic specimens from 192 primary breast carcinomas. All tumors were also assayed biochemically for ER with the dextran-coated charcoal method (DCC). The comparison of biochemically and immunocytochemically determined ER status showed concordant results in 80% (P less than 0.0001). In only 2 cases (1%) with low ER levels (less than 20 fmol/mg protein) immunocytochemistry failed to detect ER. ER positivity determined with a semiquantified approach based on intensity and heterogeneity of immunocytochemical staining correlated significantly with biochemically determined ER levels (P = 0.0001). In a series of fine-needle aspirates of 34 breast carcinomas sufficient cell material was available for ER immunocytochemistry (ER-ICA). Overall, the results of ER-ICA in fine-needle aspirates were concordant with ER-ICA in histologic specimens in 88% of the samples. In a few cases with weak positivity of ER-ICA in histologic specimens, ER-ICA was negative in fine-needle aspirates. In no case was there a false-positive immunocytochemical ER determination in a tumor aspirate. Thus, ER-ICA seems to be a reliable assay which can be performed in histologic and cytologic specimens.