Methylation levels in adenomatous polyposis coli (APC), homeobox gene A9 (HOXA9), retinoic acid receptor beta 2 (RARβ2), and Ras association domain-containing protein 1 (RASSF1A) were assessed as a novel non-invasive method for lung cancer subtyping. This evidence concerns the gene RASSF1 and lung cancer.