ERBB2 and gastric cancer: HER2-HER3 co-expression also significantly shortened the survival time and overall survival rate compared with the remaining GC patients (Log-rank test, P = 0.12, Fig. 4g); significant differences were also found among detailed categories, including HER2-HER3 co-expression, HER2 positive and HER3 negative, HER2 negative and HER3 positive, and HER2 and HER3 negative (Log-rank test: P = 0.005, Fig. 4h).