SHOX2 and head and neck cancer: Hypermethylation of both tested gene loci has been associated with other cancer entities, carcinogenesis of which is influenced by alcohol and tobacco consumption, e.g., lung cancer, gastric cancer, cancer of the hepatobiliary tract system, pancreatic cancer, and head and neck cancer.13,15,19,22,23 According to the presumed non-specificity of SEPT9 and SHOX2 methylation levels regarding tumour-site and organ, they might also be applicable for the detection of occult second primary cancers.15