Major steps forward have been made for GC, with the identification first of HER2 overexpression and HER2/neu (ERBB2) amplification as predictive biomarkers for trastuzumab (Herceptin®; Genentech, San Francisco, California) efficacy in the metastatic setting, and more recently with the introduction of two novel genomic classifications by The Cancer Genome Atlas (TCGA) Research Network [4] and the Asian Cancer Research Group (ACRG) [5]. The gene discussed is ERBB2; the disease is gastric cancer.