Multiple genes, such as CDKN2A, DAPK, MGMT, RARB, RASSF1A, and TERT, have been found to be methylated early in lung premalignant lesions, and the level of methylation increases with tumor progression from premalignant lesions to neoplasms [39,40,41,42,43]. The gene discussed is RARB; the disease is medical procedure.