ERBB2 and gastric cancer: According to the National Comprehensive Cancer Network (NCCN) and The Chinese Society of Clinical Oncology (CSCO) clinical guidelines [18, 19], human epidermal growth factor receptor 2 (HER2) status testing is recommended for all patients with GC; programmed death protein-1 (PDL1) expression and microsatellite instability (MSI)/mismatch repair (MMR) status evaluation is recommended for patients with GC who are to undergo immunotherapy; and neurotrophic tropomysin-related kinase (NTRK) gene fusion testing is recommended for patients with GC who have failed to respond to standard treatment.