KRAS and non-small cell lung carcinoma: Similar to previous study [17, 21, 22, 35], patients with wild-type EGFR were associated higher expression level of PD-L1 compared with those with EGFR mutation, which gives the rationality to immunotherapy for NSCLC patients with wild-type EGFR. On the contrary, patients harboring KRAS mutation or ALK rearrangement might also have significantly higher frequency of positive PD-L1 expression.