Chinese guidelines for HER2-targeted therapy in gastric and gastroesophageal junction adenocarcinoma (2025 Edition)

Gastric and gastroesophageal junction adenocarcinoma (GC/GEJC) poses a substantial clinical burden in China. This updated guideline introduces a refined human epidermal growth factor receptor 2 (HER2) classification system (high, intermediate, low, absent) to redefine patient stratification for targeted therapy. It integrates cutting-edge evidence on standardized detection-including immunohistochemistry, in situ hybridization, and liquid biopsy-to overcome spatial-temporal heterogeneity. Recent progress in the use of HER2-targeted agents, including monoclonal antibodies, antibody-drug conjugates, tyrosine kinase inhibitors, and bispecific antibodies, is systematically reviewed and presented to inform evidence-based clinical practice. These updates aim to optimize personalized HER2-targeted therapy and improve outcomes in GC/GEJC patients.