In NSCLC, promoter hypermethylation of P16INK4a gene which encodes a cyclin-dependent kinase inhibitor, has been found in variety of studies with a frequency of 17% [26] to 83% [23] in the tumor tissue and 6% [29] to 80% [23] in autologous clinical samples. This evidence concerns the gene CDKN2A and neoplasm.