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A risk factor is anything that affects a person's chance of
getting a disease. Although the exact cause of anal cancer is not
known, most anal cancers seem to be linked to infection with HPV (human
papilloma virus). Still, most people with HPV infections do not get anal
cancer. The risk factors for anal cancer are listed below. But risk
factors don't tell us everything. Having a risk factor, or even several
risk factors, does not mean that you will get cancer. Also, people
without risk factors can still get cancer.
Risk factors for anal cancer
HPV (human
papilloma virus): Most doctors think that squamous cell
anal cancer is caused by this virus. There are several subtypes of the
virus, but the one most likely to cause anal cancer is called HPV-16.
HPV-16, as well as HPV-18, HPV-31, HPV-33, and HPV-45 are called
high-risk types of HPV because they are strongly linked to cancer. The
virus is spread during sex. It is more likely to be found in people who
have had many sex partners. One sign of infection with this virus is
genital warts, but most people infected with HPV do not have genital
warts or any other sign of infection.
HIV infection:
People who have the human immunodeficiency virus (HIV), the virus that
causes AIDS, are much more likely to get anal cancer than those who
don't. Drug treatment for HIV has lowered the risk for many
AIDS-related diseases, but it hasn't lowered the anal cancer rate.
Sex:
Having many sex partners increases the risk of HIV and HPV infection.
Having anal sex is a risk factor for both men and women, especially for
those under the age of 30.
Smoking:
Harmful chemicals from smoke get into the bloodstream and increase the
risk of anal cancer in smokers. Current smokers are several times more
likely to have cancer of the anus compared with people who never
smoked. Quitting smoking reduces this risk. People who used to smoke
but have quit are only slightly more likely to get anal cancer compared
with people who never smoked.
Weakened immune
system: People with weak immune systems are at higher risk
for anal cancer. This includes people who have had transplants and who
must take drugs to suppress their immune systems.
Last Medical Review: 09/08/2009
Last Revised: 09/08/2009
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