Several studies reported that the expression of PD-L1 is closely related to EGFR (18) mutations, KRAS (19) mutations, smoking history (19) and advanced tumor stage (18, 20), but we failed to define a significant correlation between PD-L1 expression and these clinical features in LADC, which is concordant with the results of other studies (20, 21). The gene discussed is EGFR; the disease is neoplasm.