Prevalence of anal HPV (human papillomavirus) infection is significantly higher among men with HIV than HIV-negative men who have sex with men (MSM), investigators from the United States report in PLOS ONE. Overall, men with HIV had higher rates of infections with the HPV types strongly and weakly associated with anal cancer, and also lower risk HPV types. For men with HIV, high levels of adherence to antiretroviral therapy and an undetectable viral load were protective against high-risk HPV types.
“Our analyses support strategies that seek to increase HIV-medication compliance and promote lower HIV-load characteristics among HIV-infected MSM so as to lower risk for most hrHPV [high-risk HPV],” comment the authors.
They describe anal cancer as a “health crisis” for gay, bisexual and other MSM, noting that rates of the malignancy in the US currently exceed those for cervical cancer before the introduction of screening.
HPV-16 and eleven other HPV types are associated with a high-risk of ano-genital cancers (group 1 HPV types) and 13 other HPV types (group 2 HPV types) have a possible or probable association with these malignancies. A number of other HPV types can cause anal warts, but are associated with a low risk of cancer.
Investigators from the Multicenter AIDS Cohort Study wanted to see if HIV status, age, social and demographic factors, and sexual behaviour were associated with infection with various HPV types.
A total of 1262 MSM enrolled in the cohort had anal Pap smears between May 2010 and February 2011.
The average age of participants was 55 and 79% were white. Almost half (46%) were HIV positive. Overall, 80% of men had anal infection with one or more HPV type. Prevalence was higher among HIV-positive than HIV-negative men (91 vs 70%). Men living with HIV also had a higher prevalence of HPV-16/18 (31 vs 20%).
Three-quarters of men tested positive for multiple HPV types. Multiple HPV risk groups and individual types were significantly more likely to be detected in men with HIV (p < 0.05). HIV-negative men were approximately 80% more likely to have a solitary HPV type than men with HIV (25 vs 14%).
Overall, prevalence of group 1, group 2 and low risk types was between 35 and 92% higher among HIV-positive MSM with CD4 cell counts over 500 cells/mm3, between 500-350 cells/mm3 and below 350 cells/mm3 compared to HIV-negative individuals.
Men reporting four or more recent receptive anal sex partners had a prevalence of group 1, group 2 and low-risk HPV types that was between 17 and 35% higher than that seen in men reporting fewer recent partners. Individuals reporting over 30 lifetime sexual partners had a significantly higher prevalence of low-risk HPV types.
For men with HIV, complete adherence to antiretroviral therapy (p = 0.02) and maintaining a viral load below 50 copies/ml (p = 0.04) were protective against infection with the high-risk HPV types. In addition, prevalence of high-risk HPV types was 17% higher among men with a CD4 cell count below 350 cells/mm3 compared to men with a CD4 cell count above 500 cells/mm3 (p = 0.01). Higher number of recent sexual partners was associated with a higher risk of infection with HPV types with a possible or probable association with anal cancer and men with HIV reporting over 30 lifetime sexual partners were more likely to be infected with low-risk HPV types.
“Our data show that HIV-load <50 copies/ml protects against group 1 and 2 hrHPV infections and that complete adherence to CART [combination antiretroviral therapy] protects against group 1 hrHPVs, as well,” write the authors. “Important to our findings, experts conclude that even moderate HIV-related immune suppression measured as many as 6-7 years before an anal cancer diagnosis suggest that better HIV-treatment adherence may decrease risk for persistent group 1 hrHPV infections that likely cause most anal cancers.”
They conclude, “long-term mutual monogamy and smoking cessation, generally and CART-adherence that promotes HIV viremia control and prevents immunosuppression, specially among HIV-infected MSM are important prevention strategies for HPV infections that are relevant to anal cancer.”
Wiley DJ et al. Factors affecting the prevalence of strongly and weakly carcinogenic and lower-risk human papillomaviruses in anal specimens in a cohort of men who have sex with men (MSM). PLOS ONE 8(11): e79492. doi: 10.1371/journal.pone.0079492, 2013.