CDKN2A and cancer: Zhou et al., in their systematic review, reported significant increased methylation of the CDKN2A gene in head and neck carcinogenesis with an odds ratios (ORs) of 6.72, p < 0.01 (cancer versus normal), 1.89, p < 0.05 (cancer versus precancer), and 14.70, p < 0.01 (precancer versus healthy control) [28].