Evaluation of estrogen receptor immunocytochemical assay (ER-ICA) and estrogen receptor enzyme immunoassay (ER-EIA) for the determination of estrogen receptor status in breast carcinoma. A comparative study on frozen sections, cytological smears and tissue homogenates.

One hundred thirty three cases of primary breast cancer were analyzed for estrogen receptors (ERs) by two different techniques: monoclonal ER immunocytochemical assay (ER-ICA) and ER enzyme immunoassay (ER-EIA). The overall concordance between ER-ICA and ER-EIA was 89.5% despite the semiquantitative nature of the immunocytochemical evaluations. There was a significant correlation between these two methods in linear regression analysis. The correlations were evident both for ER detection on frozen sections as well, as on fine needle aspirates. Correlations between histoscores calculated independently by three pathologists might overcome the objections of subjectivity of ER-ICA evaluations. The results suggest that ER-ICA can be useful in assessing ERs in breast cancer, especially in small primary tumours, primary inoperable breast cancer, recurrences and metastases.