ERBB2 and squamous cell carcinoma: According to patient characteristics, the HER2 mutation rate was significantly higher in non-squamous cell carcinomas than in squamous cell carcinomas (3.2% vs. 1.8%, p = 0.007), as well as in histological grade III/IV than in I/II carcinomas (5.1% vs. 3.2%,p = 0.006) (Table 1).