Comparative study on FISH and IHC for detecting Her-2 gene amplification and protein expression in breast cancer

Objective To investigate the difference and the relation of immunohistochemistry(IHC)for detecting the expression of Her-2 protein and fluorescence in situ hybridization(FISH)for detecting Her-2 gene amplification in breast cancer,and to evaluate the value of the clinical application. Methods The expression of Her-2 protein and Her-2 gene amplification in 50 cases of breast cancer were detected and compared by IHC and FISH methods,respectively. Results Seven cases of Her-2 gene amplification were found in 8 cases of IHC(+++)(7/8,87.5%),6 cases of Her-2 gene amplification were detected in 7 cases of IHC(++)(6/7,85.71%),2 cases of Her-2 gene amplification were observed in 3 cases of IHC(+)(2/3,66.67%),and 2 cases of gene amplification existed in 32 cases of IHC(0)(2/32,6.25%).The accordance rate of IHC and FISH was 88.0%,and the results by two methods were significantly related(P0.001). Conclusion IHC is a preferred method for detecting the Her-2 in breast cancer.The strongly positive expression(+++)of Her-2 protein tested by IHC is greatly consistent with Her-2 gene amplification by FISH,but Her-2 gene amplification should be further detected in patients with Her-2 positive expression(+～++)by FISH in order to guide the clinical diagnosis and treatment.