It has been suggested that aberrant methylation patterns could therefore act as a selective factor on neoplastic cells, influencing patients' survival and prognosis, particularly if methylation affects expression of a tumor suppressor gene such as CDKN2A, RASSF1 or a DNA repair gene such as MGMT. For example, aberrant gene hypermethylation of CDKN2A, p14ARF [10], RASSF1 [11-13] and the DNA repair gene MGMT [3] have been reported in tumor tissue of oral cavity cancer patients (see Table 1 for a more comprehensive list of genes methylated in oral cancers). This evidence concerns the gene MGMT and oral cavity cancer.