The short answer
Most anal cancer is linked to HPV, a very common virus. Risk is higher for people with HIV, people with a weakened immune system, people with a history of cervical, vaginal, or vulvar cancer, and men who have sex with men. Smoking also raises risk. The HPV vaccine protects against the HPV types it covers.
NCI says about nine out of ten anal cancers are found in people with anal HPV infection (human papillomavirus), a very common virus.
Risk is higher for people with HIV, people taking immune-suppressing medicine (such as after an organ transplant), and people with a history of cervical, vaginal, or vulvar cancer.
Men who have sex with men, especially those also living with HIV, have a higher risk of anal cancer.
Smoking increases risk, and current smokers are at higher risk.
On this page
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The whole article, with every detail and caution.
This page is for anyone who wants to know what raises the risk of anal cancer. It covers the main risk factors, the HPV vaccine, and what to talk over with your doctor.
The simple version
Most anal cancer is linked to HPV, the human papillomavirus. NCI says about nine out of ten anal cancers are found in people with anal HPV infection. HPV is very common, and there is nothing shameful about it. Some groups have higher risk. The HPV vaccine protects against nine HPV types.
Who is at higher risk, and why
- People with HIV. NCI calls HIV a strong risk factor.
- People taking immune-suppressing medicine, such as after an organ transplant, NCI lists a weakened immune system as a risk factor.
- People with a history of cervical, vaginal, or vulvar cancer. NCI lists this history as a risk factor.
- Men who have sex with men, and people who have receptive anal intercourse or multiple partners, are listed by NCI as having higher risk.
- People with a history of anal warts. NCI lists a history of anal warts or other sexually transmitted infections.
- People who smoke. Smoking raises risk, and current smokers are at higher risk. Ask your care team for help quitting.
None of these risk factors describe something a person did wrong. They describe biology. A common virus meets immune health and exposure. Understanding that is about getting the right care, not judgment.
HPV vaccination
CDC says the vaccine in use in the U.S. protects against nine HPV types (6, 11, 16, 18, 31, 33, 45, 52 and 58). It works best when given before someone meets HPV.
- It is routinely recommended at ages 11 to 12, and can start as early as age 9.
- Catch-up vaccination is recommended through age 26 for anyone who has not finished the series.
- Some adults ages 27 to 45 may benefit and can talk it over with a doctor.
CDC recommends it for children of any sex.
What this means for you
Having one or more of these risk factors does not mean you will get anal cancer. Most people with these risk factors never do. What it does mean is worth a conversation. Ask your doctor whether closer follow-up for anal symptoms, or in some cases screening, makes sense for you.
Sources
- National Cancer Institute, Causes & Risk Factors: Anal Cancer, accessed October 2, 2026.
- Centers for Disease Control and Prevention, HPV Vaccination, accessed October 2, 2026.
Common questions
What is the biggest risk factor for anal cancer?
Anal HPV (human papillomavirus) infection. NCI calls it the main risk factor and says about nine out of ten anal cancers are found in people with anal HPV infection. HPV is a very common virus.
Does having HPV mean I will get anal cancer?
No. HPV is a risk factor, not a guarantee. Having it is nothing to be ashamed of, because HPV is very common. Ask your doctor what your own risk means.
Why does HIV raise the risk?
NCI calls HIV infection a strong risk factor for anal cancer, as is any long-term weakening of the immune system. This is biology, not a moral judgment about anyone's life or choices.
Are men who have sex with men at higher risk?
NCI lists certain sexual practices, including receptive anal intercourse and sex between men, as risk factors. This does not reflect anything wrong with a person. It means a talk with your doctor about screening is especially worth having.
Can the HPV vaccine help even if I'm already an adult?
CDC recommends it at ages 11 to 12 (it can start at 9) and says people through age 26 who did not start or finish the series also need it. Some adults ages 27 to 45 may choose to be vaccinated after talking with a provider about their own risk.
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Plain-language explanation of the published sources cited on this page. AI-assisted, source-checked, not clinician-reviewed.
Last updated: 2026-10-02Next planned review: 2027-08-03
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Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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