For instance, these studies did not find associations for smoking and methylation in the promoter region of another suppressor gene–CDKN2A (p16), while a meta-analysis of 19 epidemiological studies using the candidate genes approach demonstrated a higher frequency of the p16 gene hypermethylation in smoking vs non-smoking patients in tumor tissues of patients with diagnosed non-small cell lung carcinoma (OR = 2.25, 95%CI:1.81–2.80) [67]. This evidence concerns the gene CDKN2A and neoplasm.