Estrogen and progesterone receptor contents in ThinPrep-processed fine-needle aspirates of breast.

This study was undertaken to assess the potential value of ThinPrep-processed (Cytyc, Boxborough, MA) smears from malignant breast fine-needle aspirates (FNAs) for the determination of estrogen receptor (ER) and progesterone receptor (PR) status. The ER and PR content of 142 malignant FNAs were compared with the results of the surgically excised tumors in which the assay was done by enzyme immunoassay in 97 cases or by immunohistochemistry in 45 cases. Monoclonal antibodies directed against ER-1D5 (Dako, Carpinteria, CA) and PR-1A6 (Dako) were used with the antigen retrieval technique. By using enzyme immunoassay and immunohistochemistry as standards, the overall accuracy for ER was 97% and for PR was 89%. The results of this study show that the ThinPrep smear with microwave antigen retrieval pretreatment is a reliable method and a suitable alternative for hormone receptor analysis in breast carcinoma.