Immunohistochemical demonstration of estrogen receptors on routine paraffin sections of breast carcinomas: a comparison with frozen sections and an enzyme immunoassay.

In this study the monoclonal antibody ER-ICA (HSpy222) to human estrogen receptor (ER) protein and the peroxidase-antiperoxidase method was used to detect the presence of ER in 83 cryostat sections and in 68 paraffin sections pretreated with pronase in a total of 86 primary breast cancers. In 72 out of the 86 studied cases, a comparative evaluation was performed between the semiquantitative ER-ICA method and the quantitative enzyme immunoassay ER-EIA. A good correlation was found between the semiquantitative ER-ICA results in cryostat and paraffin sections (95.38%; p less than 0.01) in a total of 65 compared cases, concerning both the percentage of ER-positive or negative cells and the staining intensity. In addition, the overall appraisal of the lesion as ER-ICA-positive or ER-ICA-negative as well as the ER-ICA staining intensity and the proportion of ER-ICA stained cancer cells, in both cryostat and paraffin sections, correlated significantly with the mean values of fmol ER/mg determined by the enzyme immunoassay ER-EIA. The performance of the ER-ICA method on paraffin sections as used in the present study proved to be a reliable and reproducible immunohistochemical technique.