High prevalence and incidence of high-grade anal intraepithelial neoplasia among young Thai men who have sex with men with and without HIV.

Background: Men who have sex with men (MSM) are at elevated risk of having anal cancer. However, the prevalence and incidence among MSM of high-grade anal intraepithelial neoplasia (HGAIN), the putative precursor of anal cancer, is understudied, particularly in Asians.

Methods: A total of 123 HIV-positive and 123 HIV-negative MSM were enrolled at the Thai Red Cross AIDS Research Centre in Bangkok, Thailand, and followed for 12 months. Anal sample collection for human papillomavirus (HPV) genotyping and high-resolution anoscopy (HRA) with biopsies were performed at every visit.

Results: Mean age at enrollment was 28.9 years. HIV-positive MSM were more commonly infected with high-risk HPV types in the anus than HIV-negative MSM (57.5 vs. 36.6%; P  =  0.001). The prevalence of HGAIN was 18.9% in HIV-positive and 11.4% in HIV-negative MSM (P  = 0.1). The incidence of HGAIN at 12 months was 29% in HIV-positive and 8% in HIV-negative MSM (P  =  0.001). The hazard ratios for incident HGAIN in multivariate models were 5.16 [95% confidence interval (CI) 1.89-14.08, P  < 0.001] in MSM with persistent HPV 16 and/or 18 infection and 2.62 (95% CI 1.04-6.61, P  =  0.042) in HIV-positive MSM.

Conclusions: Approximately one-third of HIV-positive MSM developed incident HGAIN within 12 months. Given the relative increased prevalence of HIV among MSM worldwide, local HGAIN data are needed to guide practitioners, policy makers, and communities in planning for strategies to screen for and treat HGAIN in this population.