MGMT and lung cancer: Hypermethylation of CpG islands in gene promoters is related to the direct silencing of tumor suppressor genes, the indirect silencing of additional gene classes and genomic instability, affecting the occurrence and development of tumors.[13] As MGMT is a tumor suppressor gene, loss of MGMT expression is associated with the aggressive behavior and progression of various tumors, such as esophageal cancer, gastric cancer, hepatocellular carcinoma and lung cancer.[14] However, previous studies on whether MGMT hypermethylation affects the prognosis of patients with HNC are still controversial.