Current understanding and management of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a kind of rare head and neck cancer in Japan. However, NPC has some unique features. It is one of the most popular cancers in southern China, Southeast Asia, the Arctic, and the middle East/north Africa. This distinctive racial, ethnical, and geographic predisposition to NPC implies that both genetic susceptibility and environmental factors contribute to the development of this tumor. NPC is an Epstein-Barr virus - associated tumor. Consistent elevation of EBV antibody titers is a well-established risk factor of development of NPC. Not only pathophysiological relationship, but also molecular mechanism of EBV-mediated carcinogenesis has been enthusiastically investigated. LMP1, an EBV primary oncogene, upregulates each step of metastasis, and contribute to highly metastatic feature of NPC. A tumor suppressor gene p53 is mostly intact and overexpressed in NPC whereas expression of p16, a cyclin-dependent kinase inhibitory protein, is downregulated in 2/3 of NPC. Intention modulated radiotherapy (IMRT) is now getting prevalent for the treatment of NPC because of complicated structure and location of nasopharynx. A good therapeutic result can be achieved by distributing a high dose to the tumor while keeping down normal tissue complications by reducing radiation dose to normal tissues. Chemotherapy is important to control distant metastasis of chemoradiosensitive NPC, and thus, should play an important role. However, most effective combination of anti-tumor drugs, protocol of chemoradiotherapy has not well-established. Finally, molecular targeting therapy, including targeting EBV gene product, has been developing and on the way to the clinical use.