Can receptive anal intercourse increase risk of anal cancer?
Executive summary
Receptive anal intercourse is an established risk factor for anal cancer primarily because it increases exposure of the anal mucosa to oncogenic human papillomavirus (HPV), and multiple epidemiologic studies and cancer authorities report higher anal cancer rates in people who practice receptive anal sex — especially men who have sex with men (MSM) and people with HIV — though the precise magnitude of independent risk varies across studies and is influenced by other factors such as number of partners, HIV status and smoking [1] [2] [3].
1. What the evidence shows: repeated associations between receptive anal sex, HPV and anal cancer
Case-control and population studies going back decades find strong associations between receptive anal intercourse and anal cancer: an early case-control study reported a very large relative risk in men reporting receptive anal intercourse (relative risk ~33) [3], later case-control research showed dose–response with very high adjusted odds ratios for very frequent receptive anal intercourse (adjusted OR ~17.6 for >130 lifetime receptive acts) [4], and national cancer guidance cites receptive anal intercourse among sexual practices that elevate anal-cancer risk because they increase exposure to oncogenic HPV strains [1] [4].
2. Why HPV is central to the link — biologic plausibility and official guidance
The dominant biological mechanism is HPV infection: most anal squamous cell carcinomas are HPV-associated, and anal sexual exposure is a plausible route for transmission and persistence of oncogenic HPV types in the anal canal; public cancer authorities therefore list receptive anal intercourse alongside multiple sexual partners and sex between men as behaviors that raise anal cancer risk because they increase anal exposure to oncogenic HPV [2] [1].
3. Who is at highest risk — context matters
Risks are not uniform: HIV-positive MSM show the highest anal cancer incidence (tens of cases per 100,000 person-years), HIV-negative MSM have higher rates than the general male population, and studies report stronger, more consistent associations in men than in women, with some studies finding only modest or no statistically significant increased risk for women after adjusting for other factors [1] [3] [5].
4. Limits and confounders — what the data do and don’t prove
Available research documents associations but disentangling the independent effect of receptive anal intercourse from correlated risks — young age at sexual debut, high partner number, other sexually transmitted infections, HIV and smoking — is difficult; major reviews and databases caution that few data can fully isolate sexual behavior effects because high-risk practices co-occur with other risk enhancers, and some analyses (e.g., a NHANES-based retrospective look at women) did not find a significant difference in colorectal cancer risk by reported receptive anal intercourse [1] [5] [6].
5. How much does frequency and timing matter?
Dose and timing appear important in several studies: increasing lifetime number of receptive anal exposures and younger age at first receptive anal intercourse were associated with higher odds of anal cancer in some case-control analyses, implying cumulative exposure and earlier acquisition of HPV may raise long-term risk [4] [7].
6. Practical implications: prevention and screening focus
Because HPV is the principal causal agent, prevention strategies emphasized by cancer centers include HPV vaccination (which prevents infection with high-risk HPV types), safer-sex measures that reduce transmission risk, and attention to high-risk groups for screening or surveillance [8] [9]. Public health sources explicitly note that asking about receptive anal intercourse can inform risk assessment and prevention messaging [10] [1].
7. Bottom line and balanced conclusion
Receptive anal intercourse increases exposure to oncogenic HPV and is associated with higher anal cancer risk; the association is strongest and best characterized in MSM and immunocompromised people, while the independent effect in women is smaller and more variable across studies, and confounding factors complicate precise risk estimates — nonetheless, major cancer authorities and multiple epidemiologic studies support classifying receptive anal intercourse as a risk factor [2] [1] [3].