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.
aThe Thai Red Cross AIDS Research Centre
cDepartment of Obstetrics and Gynecology
dDepartment of Pathology, Faculty of Medicine, Chulalongkorn University
eHIV-NAT, Bangkok, Thailand
fThe Kirby Institute for Infections and Immunity in Society, The University of New South Wales, Sydney, New South Wales, Australia
gDepartment of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
hDepartment of Medicine, University of California San Francisco, San Francisco, California, USA.
Correspondence to Nittaya Phanuphak, MD, The Thai Red Cross AIDS Research Centre, 104 Rajdumri Road, Pathumwan, Bangkok 10330, Thailand. Tel: +662 253 0996; fax: +662 253 0998; e-mail: firstname.lastname@example.org
Received 24 December, 2012
Revised 20 February, 2013
Accepted 26 February, 2013