|
A risk factor is anything that affects a person's chance of
getting a disease such as cancer. Different cancers have different risk
factors. For example, exposing skin to strong sunlight is a risk factor
for skin cancer. Smoking is a risk factor for cancers of the lung,
mouth, larynx (voice box), bladder, kidney, several other organs, and
for certain leukemias.
But risk factors don't tell us everything. Having a risk
factor, or even several risk factors, does not mean that you will get
the disease. And many people who get the disease may not have had any
known risk factors.
Scientists have found several risk factors that make a person
more likely to develop nasopharyngeal cancer (NPC).
Gender: NPC
is found about twice as often in males as it is in females.
Race/ethnicity: In
the United States, NPC is most common in Chinese Americans, followed by
other Asian-American groups, African Americans, Hispanics/Latinos, and
whites.
Diet:
People who live in areas 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 "Western" diet. In contrast, some
studies have suggested that diets high in fruits and vegetables may
lower the risk of NPC.
Epstein-Barr
virus infection: Almost all nasopharyngeal cancer cells
contain parts of the Epstein-Barr virus (EBV), and most people with
nasopharyngeal cancer have evidence of infection by this virus 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 slightly older children, it often causes
infectious mononucleosis ("mono"), usually in teens.
But 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
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.
Genetic factors:
A person's genes may affect their risk for NPC. For
example, 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.
Family history: Family
members of people with NPC are more likely to get this cancer. It is
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.
Other possible
risk factors: Most (but not all) studies have found that
smoking may contribute to the development of NPC. More research is
needed to define this link.
Some (but not all) studies have also suggested that workplace
exposure to formaldehyde or wood dust may increase the risk of NPC.
Last Medical Review: 01/21/2009
Last Revised: 01/21/2009
|
