Anal Cancer Risk Factors and Prevention
Knowing your risk isn't about worrying more. It's about knowing which conversations to have and when to start having them. Some of what’s below you have control over, and some you don’t. Both are worth knowing, because the ones you can't change are often the ones that tell you when to start screening.
1. Human Papillomavirus (HPV)
HPV is the main cause of anal cancer. About 9 in 10 cases are linked to it.
HPV is a group of very common viruses. Most sexually active people get one at some point, and most never know, because the body usually clears it within a couple of years without anything happening. The problem is the small share of infections that don't clear. When a high-risk strain sticks around for years, it can slowly change the cells lining the anal canal, and those changes can eventually become cancer. HPV-16 is the strain most often involved.
We're talking about years to decades between infection and cancer, which is exactly why screening works — there's a long window to catch the changes before they become anything.
How HPV moves
Skin-to-skin contact, usually sexual. It doesn't require penetration, it doesn't require ejaculation, and condoms lower the risk without eliminating it, because HPV lives on skin that a condom doesn't cover.
There's no way to test a partner for it, no treatment that clears it on command, and no reliable way to know when or from whom you got it. That's not a comfortable set of facts, but it does lead somewhere useful: since exposure is close to universal, the things that actually change your odds are vaccination and screening, not detective work about your past.
The HPV vaccine
The HPV vaccine protects against the high-risk strains that cause most HPV-related cancers. It's the most effective prevention tool that exists for anal cancer.
Who it's for:
Routine vaccination at 11 or 12, and it can start as early as 9
Catch-up through age 26 if you weren't vaccinated earlier
Between 27 and 45, it's a conversation rather than a blanket recommendation
How many doses: two if you start before your 15th birthday, three if you start at 15 or later. Three regardless of age if you're immunocompromised, including if you're living with HIV.
If you're an adult wondering whether it's worth it: the largest trial in adults over 27 living with HIV didn't find that vaccination prevented new anal HPV infections. It may still be a reasonable choice, particularly if you've had less prior exposure. Ask your provider what it would realistically do for you.
One note on timing, as of September 2026: federal vaccine schedule recommendations are currently the subject of a court case. A January 2026 change cutting HPV to a single dose was blocked in March 2026, so the schedule above is what stands. We'll update this page if that changes.
2. Immune Status
After HPV itself, this is the biggest thing that shifts anal cancer risk.
A working immune system clears most HPV infections on its own. When it's suppressed, infections are more likely to persist, and persistence is what eventually causes cell changes.
This includes:
People living with HIV. Rates are substantially higher than in the general population, and this is the clearest risk signal. It's also why screening guidelines start earlier for people with HIV than for anyone else.
Organ transplant recipients on anti-rejection medication. Risk climbs the longer you've been on it, which is why guidelines suggest starting screening around ten years post-transplant.
People on immunosuppressive medication for autoimmune conditions.
People being treated for other cancers.
What actually helps here: staying on and adherent to HIV treatment, because sustained viral suppression and a healthy CD4 count matter. And screening, which starts earlier for you and is the reason these guidelines exist.
What won't fix it is a diet. You'll see a lot of advice about "boosting your immune system" with food and supplements, and for someone on anti-rejection drugs or living with HIV, that's not what's going on. General health is good for you and it isn't a substitute for treatment and screening.
3. A history of HPV-related precancer or cancer elsewhere
If you've had precancerous changes or cancer somewhere else HPV affects, your anal cancer risk is higher than average.
The strongest signal is a history of vulvar precancer or vulvar cancer. Anal cancer rates in that group run around 42 to 48 per 100,000 per year, which is in the same range as the highest-risk groups anywhere on this page. Screening guidelines recommend an anal exam within a year of that diagnosis.
A history of cervical or vaginal precancer or cancer also raises risk, though less sharply. So does a history of genital warts.
If any of that describes you and nobody has ever mentioned anal cancer screening, that's a gap in your care rather than a sign you don't need it. Bring it up.
4. Age
Anal cancer is rare before 35. Rates climb with age, and the highest are in people 75 and older.
That's not because getting older causes it. It's the timeline: HPV picked up decades earlier has had years to cause changes, and the immune system gets less efficient at clearing infections over time.
Bleeding, a lump, pain, itching that won't quit, or a change in your bowel habits should get looked at whatever your age. Age determines when routine screening starts. Symptoms don't wait for it.
5. Smoking
Tobacco smoke damages cells directly and makes it harder for the immune system to clear HPV, so the two risk factors compound rather than just adding up. If you smoke and you're in another higher-risk group, quitting does more for you than it would for someone at baseline risk.
The evidence on vaping and anal cancer specifically is thin. Absence of evidence isn't evidence of safety.
Quitting is hard and relapse is normal, not failure. Most people who quit for good did it after several attempts. If you want help, 1-800-QUIT-NOW and smokefree.gov are free, and some LGBTQ+ health centers run cessation programs built for our communities. Smoking rates are higher among LGBTQ+ people largely because we've been targeted by tobacco marketing for decades.
What about sex?
HPV is the risk factor. Sex is how HPV gets around. Most sexually active people are exposed at some point, and that includes people with one lifetime partner. Counting partners is not a useful way to think about your risk, and we're not going to tell you to have less sex.
What's actually worth knowing:
Condoms and dental dams help, partially. They cut HPV transmission meaningfully but not completely, because HPV lives on skin a barrier doesn't cover. Worth using, not worth trusting absolutely. They're considerably better at preventing HIV and most other STIs, which is its own good reason.
HIV status is the bigger lever here. If you're HIV-negative, staying negative does more for your long-term anal cancer risk than anything about partner count. PrEP is worth a conversation if it isn't already part of your life. If you're living with HIV, staying on treatment and in care is the thing that matters most.
Regular sexual health care means someone knows your body. Routine STI screening isn't directly anal cancer screening, but it means having a provider you see regularly, who you can tell when something's changed. That relationship is the thing that catches problems early.
Receptive anal sex is associated with higher rates of anal HPV. That's true but isn't a reason to stop. It's a reason to get vaccinated if you can, to know your screening thresholds, and to get anything unusual looked at rather than filed under "probably nothing."
Your sex life isn't a risk factor to be managed down. It's context your provider should have so they can take care of you properly.
What do you do with all this?
Risk factors are only useful if they change something. Here's what they change.
They tell you when screening starts. Anal cancer screening guidelines set different starting ages by risk group, and where you land depends on the factors above. If you're living with HIV, or you're a man who has sex with men, or you're a transgender woman, there's a specific age for you.
They tell you what to ask for. "Should I be screened for anal cancer?" is a reasonable question to put to a provider, and a lot of people who qualify have never been asked it. If you're in one of the groups above and nobody has raised it, raise it yourself.
They tell you what's worth acting on. Vaccination if you're in the age range where it helps. Staying in HIV care. Quitting smoking if you smoke.
They don't tell you what caused anything. If you've been diagnosed, none of this is a list of things you did wrong. HPV is nearly universal, most people who get anal cancer did nothing unusual, and the search for the reason it happened to you is a search that doesn't end well.
Know what's worth a phone call
Whatever your risk level, these deserve attention rather than a wait-and-see:
Bleeding that's new, or different from what you're used to
A lump or swelling near or in the anus
Pain, pressure or itching that won't settle
A change in your bowel habits that sticks around
Anything that feels like a hemorrhoid but isn't behaving like one
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HPV and Anal Cancer – The HPV and Anal Cancer Foundation
https://www.analcancerfoundation.org
This foundation provides information on anal cancer prevention, treatment, and support resources for individuals affected by anal cancer.CDC: HPV and Cancer How HPV causes cancer, and which cancers it causes. https://www.cdc.gov/cancer/hpv/
CDC: HPV Vaccination Current recommendations, dosing, and safety information. https://www.cdc.gov/hpv/vaccination-considerations/
HPV and Anal Cancer Foundation Risk information, patient support, and clinical trial navigation. https://www.analcancerfoundation.org
National Cancer Institute: HIV Infection and Cancer Risk Why immune suppression raises risk for HPV-related cancers. https://www.cancer.gov/about-cancer/causes-prevention/risk/infectious-agents/hiv-fact-sheet
Smokefree.gov Free quit tools, text programs, and a helpline. https://smokefree.gov
LGBTQ+ Healthcare Directory Find a provider you won't have to explain yourself to. https://lgbtqhealthcaredirectory.org
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Stier EA, et al. International Anal Neoplasia Society's consensus guidelines for anal cancer screening. International Journal of Cancer, 2024. https://onlinelibrary.wiley.com/doi/full/10.1002/ijc.34850
Clifford GM, et al. A meta-analysis of anal cancer incidence by risk group: toward a unified anal cancer risk scale. International Journal of Cancer, 2021;148:38–47.
Centers for Disease Control and Prevention. Cancers Linked with HPV Each Year. Last reviewed December 2025. https://www.cdc.gov/cancer/hpv/cases.html
Centers for Disease Control and Prevention. HPV Vaccination Considerations for Clinicians. https://www.cdc.gov/hpv/hcp/vaccination-considerations/index.html
Panel on Opportunistic Infections in Adults and Adolescents with HIV. Guidelines for the Prevention and Treatment of Opportunistic Infections, Human Papillomavirus section. Reviewed March 2026. https://clinicalinfo.hiv.gov
Wilkin TJ, et al. A randomized, placebo-controlled trial of the quadrivalent HPV vaccine in HIV-infected adults age 27 or older. Clinical Infectious Diseases, 2018;67(9):1339–1346.
American Cancer Society. Anal Cancer Key Statistics. Last revised August 2026. https://www.cancer.org/cancer/types/anal-cancer/about/what-is-key-statistics.html