As will be discussed, tumor tissue is the specimen type used most frequently for determining the HPV status of oropharyngeal cancer, whether through PCR-based detection of HPV DNA or HPV mRNA in situ hybridization for viral sequences or (more commonly in routine settings) immunohistochemistry for an HPV-associated biomarker (p16INK4a) (21). The gene discussed is CDKN2A; the disease is neoplasm.