الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 172 |  |  |
| | | from | 172 | | |
Abstract
The global statistics by world region reveal the distinct features of the descriptive epidemiology, the contrasting geographical and ethnic variations in the distribution of incidence worldwide of NPC, it is more frequent in males than females in both the developing and developed world, with incidence rates commonly 2 to 3 times. While the virus is considered an important step in NPC progression, only a fraction of the EBV-infected population develops the disease. Moreover, infection with the virus is considered both lifelong and ubiquitous in most areas of the world. RT is the definitive treatment for primary NPC, the best choice of treatment modality for recurrence changes with every case. Novel agent in NPC treatment is very promising. Global epigenetic disturbance is thought to contribute to carcinogenesis through oncogene activation, loss of imprinting, genomic instability, X-chromosome inactivation, and harmful expression inserted viral sequences. Side effects from agents at epigenetic modulating doses are relatively mild compared with cytotoxic agents.