Risk Factors for Nasopharyngeal Cancer

A risk factor is anything that raises a person’s chance of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, like smoking or diet, can be changed. Others, like a person's age or family history, can’t be changed.

But risk factors don’t tell us everything. Having a risk factor, or even many risk factors, does not mean that you will get the disease. And many people who get the disease may have few or no known risk factors.

Scientists have found risk factors that make a person more likely to develop nasopharyngeal cancer (NPC). These include:

• Gender
• Ethnicity and where you live
• Diet
• Infection with the Epstein-Barr virus
• Family history

Smoking, alcohol, and some workplace exposures may also increase the risk of this cancer.

Gender

NPC is found about twice as often in males as it is in females.

Race/ethnicity and where you live

NPC is most common in southern China (including Hong Kong), Singapore, Vietnam, Malaysia, and the Philippines. It's also fairly common in Northwest Canada and Greenland.

People of south China have a lower risk of NPC if they move to another area that has lower rates of NPC (like the US or Japan), but their risk is still higher than for people who are native to areas with lower risk. Over time, their risk seems to go down. The risk also goes down in new generations. Although whites born in the United States have a low risk of NPC, whites born in China have a higher risk.

In the United States, NPC is most common in Asian and Pacific Islanders (particularly Chinese Americans), followed by American Indian and Alaskan natives, African Americans, whites, and Hispanics/Latinos.

Diet

People who live in parts of Asia, northern Africa, and the Arctic region where NPC is common, typically eat diets very high in salt-cured fish and meat. Indeed, the rate of this cancer is dropping in southeast China as people begin eating a more Westernized diet. In contrast, some studies have suggested that diets high in nuts, legumes, fruits, and vegetables and low in dairy products and meat may help lower the risk of NPC.

Epstein-Barr virus infection

Almost all NPC cells contain parts of the Epstein-Barr virus (EBV), and most people with NPC have evidence of EBV infection in their blood. Infection with EBV is very common throughout the world, often occurring in childhood. In the United States, where infection with this virus tends to occur in teens, it's commonly known as mononucleosis (“mono”).

The link between EBV infection and NPC is complex and not yet completely understood. EBV infection alone is not enough to cause NPC, since infection with this virus is very common and this cancer is very rare. Other factors, such as a person’s genes, may affect how the body deals with EBV, which in turn may affect how EBV contributes to the development of NPC.

Family history

Family members of people with NPC are more likely to get this cancer. It's not known if this is because of inherited genes , shared environmental factors (such as the same diet or living quarters), or some combination of these.

Just as people have different blood types, they also have different tissue types. Studies have found that people with certain inherited tissue types have an increased risk of developing NPC. Tissue types affect immune responses, so this may be related to how a person's body reacts to EBV infection.

Other possible risk factors

Tobacco and alcohol use: Most (but not all) studies have found that smoking may contribute to the development of NPC, especially the keratinizing type. Some studies have also linked heavy drinking to this type of cancer.

Workplace exposures: Some studies have suggested that workplace exposure to formaldehyde increases the risk of NPC. Still, not all studies have shown this and this link isn’t clear.