IMPROVEMENT OF THE QUANTIFICATION OF ESTROGEN AND PROGESTERONE RECEPTORS IN PARAFFIN-EMBEDDED TUMORS BY IMAGE-ANALYSIS

It has been shown previously that estrogen receptors (ER) detected by immunohistochemical examination of paraffin-embedded tissue sections could be quantified by computerized image analysis. Several factors were identified that were, in part, responsible for the modest correlation obtained with biochemical assay results. In the present study, 45 formalin-fixed, paraffin-embedded breast carcinomas from a previous study were re-evaluated to determine if current methods could provide a better correlation and more consistent results. Sections of the tumors were made to react with estrogen and progesterone receptor antibodies (ER-ICA and PgR-ICA) and the intensity of the stain was quantified using an image analysis system. Vimentin immunostain was used to assess the degree of antigenic loss. Quantitation was performed only on the areas with nuclear staining. The correlation of the estrogen and progesterone receptor values obtained by the dextran charcoal-coated method with the percentages of stained areas and with the intensity of the stain was excellent. The agreement between both methods was 91.1% for estrogen and 86.7% for progesterone receptor values. These results represent a significant improvement compared with those found in a previous study (87% agreement for estrogen receptor). The current approach to estrogen and progesterone receptor quantitation is simplified and eliminates subjectiveness in the selection of the fields for evaluation. The studies are reproducible because discrepancies due to sampling techniques are excluded. Finally, the method validates the technique as a substitute for cytosol-based methods. The results of the two vastly dissimilar assays, the pitfalls of the ''gold standard'' dextran charcaol-coated assay, and the need for retrospective studies to acquire a range of quantified ER-ICA and PgR-ICA values with clinical significance are discussed.