Anal Cancer Causes & Risk Factors


HPV and Anal Cancer

A nurse gives a girl a vaccination.
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The human papillomavirus (HPV) is the most common sexually transmitted infection. Many people have HPV but may not know it. In most people, the virus is dormant. That means HPV is not active in the body.

For some people, HPV infection can lead to certain types of cancer. These include cervical cancer, vaginal cancer, head and neck cancer, and anal cancer.

Most anal cancer — more than 90 percent — is caused by HPV. Your risk of developing HPV-positive anal cancer depends in part on the strain of HPV that you were exposed to. For instance, some strains cause warts on the skin, mouth, or genitals but rarely, if ever, lead to cancer. Other strains put you at a higher risk of anal cancer. There are more than 150 variations of HPV, but the strain most commonly linked to anal cancer is HPV 16.

Sexual Activity

Because it increases your chances of being exposed to HPV, having multiple sexual partners can lead to a higher risk of developing anal cancer.

Having anal sex is one of the known predisposing factors of anal cancer for both men and women. The disease is more common in men who have sex with men.


Smoking cigarettes increases your risk for many types of cancer, including anal cancer. If you are currently a smoker, it is never too late to quit. Learn how MSK’s Tobacco Treatment Program can help.

Other Anal Cancer Risk Factors

These factors increase your risk as well:

  • lowered immunity due to HIV infection or immunosuppressant drugs
  • past history of other cancers, including penile cancer, cervical cancer, vaginal cancer, or vulvar cancer
  • age (people over 50 are more likely to develop anal cancer)
  • gender (women have a higher risk of anal cancer)

How to Protect Yourself against Anal Cancer

You can lower your chances of developing anal cancer if you:

  • Practice safe sex.
  • Get the HPV vaccine. The Centers for Disease Control and Prevention advises girls between ages 11 and 26 and boys between ages 11 and 21 to get vaccinated. The HPV vaccine is also approved for women and men age 27 through 45.
  • Don’t smoke, or stop immediately if you currently smoke.