Tumour cells can take advantage of two patterns of DNA methylation [415]: hypermethylation—increased methylation of CpG islands, generally associated with gene silencing of tumour suppressors such as p16 [423], MLH1 [424,425], and MGMT [72]—and hypomethylation—an overall decrease in global DNA methylation pattern, typically associated with overexpression of proto-oncogenes and growth factors [426]. This evidence concerns the gene MGMT and neoplasm.