Correlation of HER2 gene status assessment by fluorescence in situ hybridization between histological sections and cytological specimens of breast cancer.

Abstract

While HER2 gene detection in cytological specimens using fluorescence in situ hybridization (FISH) has been reported, the appropriate criteria for such specimens remain controversial. Fine needle aspiration (FNA) samples collected from surgically resected breast cancer specimens were rinsed in a cytopreservative solution containing fixative. Then, slides of the FNA samples were prepared by liquid-based cytology (LBC) (ThinPrep system, Hologic) according to the manufacturer's instructions, and a PathVision HER2 DNA probe kit (Abbott) was used for FISH staining. The results were evaluated using an automated MetaCyte imaging system (MetaSystems, Altlussheim, Germany). HER2 gene amplification was scored using the HER2/chromosome enumeration probe 17 (CEP17) signal count ratio as follows: amplified, >2.2; equivocal, 1.8-2.2; and unamplified, <1.8. The cytology results were compared with the histology results from concordant cases. Successful results were obtained in 98 of 100 cases, and results from the FNA specimens were in agreement with those from the histological sections in 97 of these 98 cases (accuracy rate, 99%; kappa, 0.962). FISH-based assessment of the HER2 gene status is consistent between histological sections and cytological specimens of breast cancer.