ERBB2 and gastric cancer: The most widely accepted first-line chemotherapy regimen for advanced GC is the combination of platinum and fluoropyrimidine, and trastuzumab could be considered if the tumor harbors positive human epidermal growth factor receptor type 2 (HER2).[19,20] Furthermore, trastuzumab plus S-1 demonstrates promising activity in elderly HER2-positive, advanced GC patients,[21] however, the optimal second- and third-line therapy is still a matter of debate.