Objective  To investigate the consistency and clinical significance of human epidermal growth factor receptor-2 (HER2) protein expression and gene amplification in breast cancer tissue, and to analyze the correlation between HER2 gene amplification and clinicopathological characteristics.

  Methods  Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) were used to detect the protein expression and gene amplification in 101 patients with invasive breast carcinoma. The difference of the results of two different detection methods were analyzed and clinical significance was analyzed.

  Results  In 101 cases of invasive breast cancer, IHC showed HER2 protein was negative in 1 case, positive in 6 cases, double-positive in 81 cases, and triple-positive in 13 cases. FISH showed that there were 75 cases of HER2 gene without amplification, and 26 cases of HER2 gene with different degrees of amplification. No HER2 gene amplification was observed in 1 case of HER2 protein (-) and 6 cases of HER2 protein (+), HER2 gene amplification was observed in 14 of 81 cases of HER2 protein () and in 12 of 13 cases of HER2 protein (). In 101 cases, 9 cases of chromosome 17 polysomes were found by FISH. The difference between FISH and IHC was statistically significant (P < 0.05). FISH results were correlated with age of patients (P < 0.05), and there was no correlation between FISH results and tumor histological grade, tumor maximum diameter, Ki67 expression and axillary lymph node metastasis (P>0.05).

  Conclusion  IHC has high consistency with FISH. IHC staining intensity is positively correlated with gene amplification status. IHC method can be used as the primary screening method for clinical use of Trastuzumab, and FISH test should be used together to determine clinical medication and judge the prognosis of patients.