ABSTRACT
There are a variety of techniques available to determine HER2 status in breast cancer, some of which are employed for research purposes only.9,10,16 In diagnostic pathology laboratories, HER2 status is routinely assessed either by immunohistochemistry (IHC), which assesses expression of the HER2 oncoprotein, and in situ hybridization (FISH), which measures the number of HER2 gene copies or gene amplification.17,18 Modifications of ISH using colorimetric detection are increasingly being developed including chromogenic in situ hybridization (CISH) or silver enhanced in situ hybridization (SISH).19-24
This chapter reviews the various methods used to detect HER2 expression as well as HER2 gene status as a prognostic and predictive factor, paying particular attention to criteria for robust and accurate HER2 diagnostics. Future prospects for novel HER2 biodirected therapies are also briefly considered.
