KRAS and squamous cell carcinoma: The difference in survival among three groups was also seen among patients with adenocarcinoma with median OS of 7.7, 38.0, and 16.1 months, respectively (P<0.001), on the other hand, it was not significant in patients with squamous cell carcinoma due to small number of patients with KRAS mutation (n = 1) or EGFR mutation (n = 5), (Fig. S1).