The role of Epstein-Barr virus in the management of undifferentiated nasopharyngeal carcinoma

Cancer of the nasopharynx was first documented and reported by Regaud and Schmincke separately in 1921. According to the World Heal Organization (WHO) classification, nasopharyngeal carcinoma could be classified into 3 types according to the differentiation status. Among which, type 3 undifferentiated NPC is consistently associated with Epstein-Barr virus (EBV) infection. Clinical examination relies very much on conventional imaging with the use of endoscopy and histological assessment of the endoscopic biopsy. To localize and evaluate the extent of tumor in the head and neck regions, computerized tomography (CT) scan and magnetic resonance imaging (MRI) of the skull base will be employed. These approaches however cannot be applied for routine follow-up examination and screening high-risk population for early cancer detection. In view of the close association EBV with type 3 NPC, the use of EBV-derived genes or gene products are proposed in the surveillance of undifferentiated NPC on tissues obtained with non-invasive means including nasal swabs and peripheral blood. Here, the potential application of EBV DNA and viral proteins in different clinical aspects are discussed. In light of the recent discovery of EBV-encoded microRNA in the undifferentiated NPC, the potential application of these small RNA units in the NPC patients will also be examined.