A systematic review did not find any strong correlations [10], while a later meta-analysis found high PD-L1 expression associated with male gender, smoking, poor tumor differentiation, large tumor size, presence of lymph node metastasis, EGFR wild-type status, and KRAS mutations (whereas ALK translocation status could not be correlated to PD-L1) [11]. This evidence concerns the gene KRAS and neoplasm.