In quest of a novel therapeutic target for gastric cancer, HER2 overexpression has been tested and was reported in 6-35% of stomach and gastroesophageal tumors [5]. Trastuzumab, a humanized monoclonal antibody which selectively targets HER2, has shown survival benefit in patients with HER2(+) metastatic breast cancer [6-8]. The ToGA trial is the first randomized, prospective, multicenter, phase III trial to study the efficacy and safety of trastuzumab in HER2(+) GC [9]. Of 3,807 tumor samples screened for Her2 status, 22.1% were Her2 positive and 594 patients were randomized to receive chemotherapy alone or chemotherapy + trastuzumab.