The prevalence of CGI/promoter methylation in lung cancers, including LADC, has been reported to differ between S and NS; specifically, higher methylation of CDKN2A, MGMT, RASSF1, MTHFR, and FHIT promoters has been observed in S vs. NS, whereas RASSF2, TNFRSF10C, BHLHB5, and BOLL methylation is more common in NS than in S [13]. Here, MTHFR is linked to lung cancer.