MGMT and cancer: Changes in the cellular DNA methylome resulting in hypermethylation of tumor suppressor genes including APC, BRCA1, E-cadherins, DAPK1, hMLH1, p15, Rb, MGMT, and p16INK4a have been documented in tumors from a variety of cancers including breast, colon, gastric, ovarian, lung, brain, ovarian, renal, kidney, prostate, thyroid, lymphoma, and leukemia [11, 19, 20].