Comparison of immunohistoehemistry and fluorescence in situ hybridization for assessment of HER2 in breast cancer and its clinical significance

Objective To investigate the conformity between the HER2 protein examined by immunohistochemistry(IHC) and the HER2 gene detected with fluorescence in situ hybridization(FISH) and evaluate the clinical significance.Methods IHC and FISH were used to detect the expression of HER2 protein and amplification of HER2 gene,respectively,in paraffin-embedded tissues from 77 patients with breast cancer,the conformity beteween the results obtainde by the IHC and FISH was studided.Results Among 77 cases of paraffin-embedded specimens of breast cancer patients,37 cases(48.05%) were positive by IHC,while 40 cases were negative(51.95%);HER2 gene amplification was found in 32 patients(41.56%) by FISH,gene non-amplification in 45 cases(58.44%).In 37 patients whose HER2 proteins were positive,HER2 gene amplification was found in 30cases,resulted in a coincidence of 81.08%(30/37).In 40 patients whose HER2 proteins were negative,HER2 gene non-amplification was found in 38 cases,resulted in a coincidence of 95%(38/40).There was no significant difference between the two methods(χ2=1.78,P=0.1824).The kappa test result showed that κ=0.7647,there was good agreement between the two methods.Conclusion There were a high coincidence between the HER-2 gene examined by FISH and the HER2 protein detected with IHC.