Causes & Risk Factors
What causes NPC?
The causes of Nasopharyngeal Cancer (NPC) are multiple and they include Epstein Barr Virus infection; ethnicity; age and gender, family history and environmental factors.
Research studies confirm that Chinese individuals are particularly susceptible to developing NPC. Inuit, North African, Portuguese as well as those from Mediterranean regions, the Middle East, Brazil, and a small pocket in Northern India are also all highly susceptible.
Multiple Epstein-Barr Virus (EBV) DNA copies are found in almost every nasopharyngeal cancer tumor cell, including those in the early stage of cancer cell formation. In comparison there are no EBV DNA presence in healthy nasopharyngeal epithelial cells. These findings suggest that EBV plays a critical role in the early stage formation of NPC.
The following factors may increase or contribute to the risk of developing NPC.
EBV was classified by the International Agency for Cancer Research (IARC) as a Class I carcinogenic factor for NPC in 1997; however, EBV alone is not enough to cause NPC. NPC has a multi factorial etiology and they include genetic and environmental factors that also contribute to the development of NPC.
Genetic plays a key factor in the risk of developing NPC. Even though NPC may be rare overall in the world, it is very prominent in certain ethnic groups (such as Chinese) likely due to some genetic changes occurred with these ethnic groups.
Chinese individual with family history of NPC have significant higher risks of NPC as compared to those without family history.
Age & Gender
The risk for NPC changes according to age and gender. The incidence of NPC rises sharply after a certain age (start from age 30 and peak at 50-55). The incidence between males and females is also different. A man’s risk is 3 times higher than a woman’s.
Studies have shown that the risk for developing NPC is 2 to 15 times that of the general population in endemic regions for a person with a first-, second- or third-degree relative diagnosed with NPC.
According to the American Cancer Society, many published literature confirm that dietary intake of nitrite and nitrosamine, as found in Cantonese salted fish and preserved foods is closely linked to developing NPC. Occupational exposures to wood dust and formaldehyde; environmental co-factors such as outdoor air pollution and particular matter (The World Health Organization’s International Agency for Research on Cancer (IARC), classifies both outdoor air pollution and particulate matter (PM) as class I carcinogens) have all been shown to link to higher risks of developing NPC
Reference: Yu-Bei Huang, Feng-Ju Song, Qun Liu, Wei-Qin Li, Wei Zhang and Ke-Xin Chen.
A bird’s eye view of the air pollution-cancer link in China. Chin J Cancer. 2014; Vol. 33 Issue 4:176-188.