Evaluation of analytical accuracy of HER2 status in patients with breast cancer: Comparison of HER2 GPA with HER2 IHC and HER2 FISH.

Human epidermal growth factor receptor 2 (HER2) gene status and overexpression, occurring in ~ 13.6% of primary breast cancers, is essential for identifying patients likely to benefit from biological treatment. In this method of evaluation study, we tested and compared the HER2 gene-protein assay (GPA) with routine HER2 immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH).