ERBB2 and gastric cancer: The landmark ToGA trial revealed that trastuzumab plus chemotherapy significantly improved the overall survival of patients with advanced GC [14], especially for patients with HER2 positivity, who were identified as having HER2 immunohistochemistry (IHC) scores of 2 + and fluorescence in situ hybridization (FISH)-positive or HER2 IHC 3 + based on a post-hoc exploratory analysis [92].