Aberrant promoter methylation of genes, such as CDKN2A, mutL homolog 1 (MLH1), mutS homolog 2 (MSH2), APC regulator of Wnt signaling pathway (APC), retinoic acid receptor beta (RARB), and O‐6‐methylguanine‐DNA methyltransferase (MGMT) has been described in lung cancer.49 This evidence concerns the gene RARB and lung cancer.