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.

Some of the risk factors that make a person more likely to develop nasopharyngeal cancer (NPC) include: 

Sex

NPC is found in males two to three more times more often than it is in females.

Race/ethnicity and where you live

NPC is most common in Asia, specifically eastern and southern China (including Hong Kong), Singapore, Vietnam, and the Philippines. It's also fairly common in parts of North Africa and the MIddle East, as well as the Artic.

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 White people born in the United States have a low risk of NPC, White people born in China have a higher risk.

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 starting at an early age. The process of cooking the salted food seems to make chemicals, such as nitrosamine, which is a probable carcinogen. The rate of this cancer is dropping in southeast China and Singapore and it might partly be from people eating less of the salted fish. 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.

Age

In areas of the world where NPC is not common, older age is a risk factor. 

In places where NPC is more common, the cancer tends to be seen in younger people. For example, about 1 in 5 people with NPC are younger than 30 years old and the number of people diagnosed with NPC starts to go down after about age 59.  

Epstein-Barr virus infection

Infection with the Epstein-Barr Virus (EBV) is very common throughout the world, often occurring in children. In the United States, where infection with this virus tends to occur in teens, it's commonly known as mononucleosis or mono.

EBV infection has been linked to the development of NPC, as well as certain lymphomas. It is often found in the non-keratinizing, undifferentiated type of NPC. But infection alone with EBV 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 or smoking may affect how the body deals with EBV, which then may affect how EBV plays a part in the development of NPC.

EBV DNA can be found in NPC cells and also pre-cancer cells. EBV DNA can also be found in the blood of people with NPC.

The link between EBV infection and NPC is complex and still being studied.

Human papillomavirus (HPV)  infection

Human papillomavirus (HPV) is a group of more than 150 types of viruses. Infection with certain types of HPV can cause some forms of cancer, including cancers of the mouth and throat. 

Some research shows that certain high-risk types of HPV may be linked to a small group of NPC cases especially in younger people who don’t smoke.

See HPV (human papillomavirus) to learn more about HPV and vaccines to prevent HPV infection.

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 use: Many studies have found that smoking may contribute to the development of NPC. Smoking might increase the risk of NPC by reactivating an EBV infection.

Alcohol use: Some studies have also linked heavy drinking of alcohol to this type of cancer. This is seen more often in the US and Europe. More research is being done. 

Source: https://www.cancer.org/cancer/types/nasopharyngeal-cancer/causes-risks-prevention/risk-factors.html