ERBB2 and gastric cancer: According to HER2 amplification and PD‐L1 expression, GC patients were stratified into four subgroups for further analysis (Figure 3A), including HER2−/PD‐L1− (54.56% [401/735], HER2 other and PD‐L1 CPS <1), HER2−/PD‐L1+ (35.1% [258/735], HER2 other and PD‐L1 CPS ≥1), HER2+/PD‐L1− (5.85% [43/735], HER2 amplification and PD‐L1 CPS <1) and HER2+/PD‐L1+ (4.49% [33/735], HER2 amplification and PD‐L1 CPS ≥1).