Brain Metastasis from Nasopharyngeal Carcinoma

Epidemiology and Etiology

Nasopharyngeal carcinoma (NPC) has a distinct geographic and ethnic distribution, which is a result of a multifactorial etiology. NPC is rather rare in many parts of the world such as North America, but it is considered endemic in certain parts of Asia, particularly in southern China, Southeast Asia, the Arctic, North Africa, and the Middle East ( ; ; ). Migrant epidemiologic data show that even after immigrating to a different geographic area, there is still a high incidence of NPC in offspring compared to the local population ( ; ). American-born second-generation Chinese and North Africans maintain the risk of NPC ( , NPC website). Therefore, a high index of suspicion is advised in this patient population.

The risk of NPC increases slowly throughout life. About half of the patients with NPC in the United States are younger than age 55 years, but it can occur at any age, including pediatric patients, and it has a male predominance ( , NPC website).

Epstein-Barr virus (EBV), a virus with growth-transforming potential for human B cells, is associated with certain B-cell lymphomas and also with undifferentiated NPC (epithelial tumor). The relationship between risk factors is not straightforward, as only a minor portion of the population infected by EBV developed NPC ( ). Other recognized risk factors for NPC are cigarette smoking (especially the keratinizing NPC type), occupational exposure to formaldehyde, diets very high in salt-cured fish and meat, and wood dust. It seems that the interaction of multiple risk factors such as genetic predisposition, EBV infection, gender, and environmental carcinogens is responsible for developing NPC ( ). According to numerous reports, the human leukocyte antigen system might play an important role in the pathogenesis of NPC and be responsible for genetic predisposition to develop NPC in areas of high prevalence such as Southern Asia, the Mediterranean, and Northern Africa ( ).