A reliable method of demonstrating HER-2/neu, estrogen receptors, and progesterone receptors on routinely processed
G T McKee1, R H Tambouret, D Finkelstein
1Department of Cytopathology, Massachusetts General Hospital, Boston 02493, USA. gmckee@partners.org
Abstract:
Estrogen (ER) and progesterone receptors (PR) and HER-2/neu (c-erbB-2) protein overexpression are important prognostic factors for breast carcinoma. This study describes a simple, rapid method that demonstrates the applicability of these tests to cytology smears. Smears were made from scrape samples of fresh breast tumors and were fixed in 95% alcohol for immunohistochemical staining for ER and PR and HER-2/neu protein overexpression. Scraped material was suspended in phosphate-buffered saline, and cytospin slides were prepared from the suspension and air dried for fluorescence in situ hybridization (FISH). The results for ER performed on cytology compared with the gold standard (immunohistochemistry on histology) showed 94% accuracy (95% confidence bounds (0.8432 0.9823)); PR results showed 71% accuracy (95% confidence bounds (0.5805 0.8180)) and HER-2/neu results showed 77% accuracy (95% confidence bounds (0.6500 0.8709)). Using HER-2/neu gene overamplification detected by FISH as the gold standard, immunohistochemistry for HER-2/neu protein overexpression showed sensitivity, specificity, and a positive predictive value of 88.8%, 77.7%, and 80% for histology, respectively, and 69%, 87%, and 90% for cytology, respectively. This study showed that fixation and storage of smears in 95% alcohol were effective for receptor studies, whereas air-dried cytospin smears were well suited to FISH.
