ERBB2 and gastric cancer: There are various approaches to GC therapy, including perioperative, adjuvant, and palliative chemotherapy, and tumor endoscopic/surgical resection, none of which is fully effective.4 Targeted therapy has been also introduced for a particular subset of GCs that overexpress human epidermal growth factor receptor 2 (HER2).7–9 More recently, a great deal of attention is being given to immunotherapy, which may be used in various types of cancers, including GC.10