In a new study published in the Journal of Infectious Diseases, Pragna Patel, MD, MPH, and her colleagues set out to characterize the epidemiology of human papillomavirus (HPV) infection in men who are infected with HIV. HPV infection can lead to anal cancer and it is estimated that men who have sex with men (MSM) are 20 times more likely to develop anal cancer than heterosexual men. In addition, the authors note that HIV-infected MSM are more likely to develop anal cancer than HIV-uninfected MSM, with incidence rates being approximately 80 times higher for HIV-infected MSM in comparison to HIV-uninfected men.
Furthermore, studies have shown that HIV-infected MSM are less likely to clear anal HPV infection, particularly for HPV type 16. This is particularly concerning as failure to clear HPV types 16 and 18 is a known risk factor for developing anal cancer. Although vaccination can potentially prevent anal high-risk HPV infections, current vaccination protocols and clinical guidelines would certainly benefit from in-depth epidemiological studies. Therefore, Dr. Patel and her colleagues sought to fill in this missing link.
A total of 700 HIV-positive patients from 7 clinics in 4 cities were enrolled in the Study to Understand the Natural History of HIV/AIDS in the ERA of Effective Therapy (SUN study) from March 2006 until June 2006. Of the 700 patients enrolled in the SUN cohort, 525 were men and 499 had an HPV positive result during the baseline visit. The men were asked to self-report on their sexual behavior and were thus classified as either MSM (81%) or men who have sex with women (MSW) (19%). Most of the participants were receiving highly active combination therapy (cART).
The investigators found that the anal prevalence of HPV was 95% for MSM and 59% for MSW, with high-risk HPV types detected in 85% of MSM and 48% of MSW. The most common types of HPV found among both MSM and MSW was 16 and 6. In addition, when compared to HIV-infected MSW, MSM had an increased likelihood of having abnormal anal cytology. The investigators attributed these results to sexual behavior differences between MSM and MSW, with MSM reporting a greater number of sexual partners than MSW.
Although the study results showed that MSM had higher incidence and prevalence of anal HPV infection, they determined that clearance and persistence rates of high-risk HPV types were not different between the 2 groups.
Some limitations of the study include the lack of an HIV-negative group of men for comparison purposes as well as an inability to quantify the number of HPV virions detected. In addition, the SUN study only collected anal specimens on a yearly basis, which could lead to an overestimation of HPV incidence. The investigators noted that they were also unable to distinguish between an episode of HPV re-infection and failure to clear an HPV infection.
Nonetheless, this work sheds light on the prevalence of HPV in HIV-infected men which can help shape future screening protocols and recommendations in this population.
By Samar Mahmoud