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

OBJECTIVE: To evaluate the sensitivity and specificity of chromogenic in-situ hybridization (CISH) in detecting HER2 gene amplification in breast carcinomas. METHODS: HER2 oncogene amplification and its protein expression in 165 cases of breast carcinoma were investigated by immunohistochemistry (IHC) and CISH. RESULTS: (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. CONCLUSIONS: 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.