Since 2001, HER2 testing has been recommended for all patients with a new diagnosis of invasive breast cancer or metastatic patients that have not had a previous HER2 test performed. There are several testing methods to assess HER2 status, but the two primary methods in clinical laboratories are immunohistochemical (IHC) staining and fluorescence in situ hybridization (FISH). There are options for the performance of both methods.
