We chose CDKN2A and RASSF1 since hypermethylation of these genes has been widely reported in a variety of cancers including NSCLC [15,21,22], and the EN1 promoter region since hypermethylation of EN1 had been previously reported in a lung tumor cell line [29] but not yet in primary NSCLC tumors. This evidence concerns the gene CDKN2A and non-small cell lung carcinoma.