For accurate selection of participants who will be treated with anti-HER2, primary crucial thing to do is the right identification of HER2 in breast tumor cells. The advantages and disadvantages of IHC and In-Situ Hybridization (ISH) for the detection of HER2 status is still disputable. It is generally agreed on that HER2 study should be applied on all invasive breast cancer participants. It can be used together with IHC which measures HER2 protein expression or ISH which assesses HER2 gene amplification. With regard to IHC, the inconsistency of sensitivity and specificity of marketed antibodies, differences in interpretation and technical artifacts cause problems in diagnosis on occasion. There is not enough study on reasons which cause the consistence and discrepancies between laboratories in HER2 detection with IHC method.
