Epigenetics is the study of heritable changes in gene regulation that do not involve a change in the DNA sequence or the sequence of the proteins associated with DNA. The most studied of epigenetic changes is that of DNA methylation, which occurs primarily in CpG dinucleotides and is often altered in cancer cells. Both hypermethylation and hypomethylation contribute to tumorigenesis. Gene-specific hypermethylation can affect many different types of cancers and is often mediated through the silencing of tumor suppressors [1]. Hypomethylation can contribute to genomic instability that is frequently observed in cancer [2], activation of oncogenes, or loss of imprinting which are also causes of oncogenesis [3].