Analysis of HER2 gene amplification and its protein expression in 165 cases of breast carcinoma: comparison of chromogenic in-situ hybridization and immunohistochemistry

To evaluate the sensitivity and specificity of chromogenic in-situ hybridization (CISH) in detecting HER2 gene amplification in breast carcinomas.HER2 oncogene amplification and its protein expression in 165 cases of breast carcinoma were investigated by immunohistochemistry (IHC) and CISH.(1) CISH did not detect HER2 gene amplification in 107 cases of IHC negative tumors and 24 cases of IHC 1+ tumors. (2) CISH identified high copy numbers of HER2 gene amplification in 21/22 (95.5%) cases with IHC 3+. (3) In 12 HIC 2+ cases, CISH identified 3 cases of high copy number amplification, 6 cases of low copy number amplification and 3 cases without amplification.HER2 gene amplification detection by CISH is highly sensitive and has a high concordance with IHC detection of the protein expression. It is concluded that CISH is a tool to evaluate HER2 gene status in breast cancer and can be an implement in conventional pathology laboratories.PubMed07457-603