Viral cancerogenesis of head and neck tumors

Approximately 15% of malignant diseases are caused by infectious agents. Human papilloma viruses (HPV) can be frequently found in oral carcinomas, especially tonsillar cancer. A group of HPV-infected tumors shows clear signs for a virally induced transformation process: high-risk HPVs can be detected in all tumor cells, the viral oncogenes E6 and E7 are constantly expressed and lead to upregulation of cellular p16(INK4a), a cyclin-dependent kinase inhibitor. The patients frequently lack typical risk factors associated with head and neck cancers such as drinking and smoking. Epstein-Barr viruses (EBV) are associated with lymphoproliferative disorders and cause nasopharyngeal carcinoma (NPC). NPC has a high incidence in some East Asian countries. In this review, the molecular pathogenesis of HPV- and EBV-associated malignancies are described and the clinical relevance of the presented findings is discussed.