Abstract
BackgroundAnal cancer, one of human papillomavirus (HPV) related malignancies, has increased in recent decades, particularly among men who have sex with men (MSM) and HIV-infected (HIV+) persons. We aimed to explore the prevalence of anal squamous intraepithelial lesions (ASIL) using Papanicolau (Pap) screening among MSM in northern Thailand and its associated factors.MethodsTwo hundreds MSM aged ≥18 years reporting receptive anal intercourse in the prior 6 months were recruited from July 2012 through January 2013. Medical history and behavioral data were collected by staff interview and computer-assisted self interview. Anal Pap smear, HPV genotyping, and HIV testing were performed. Two pathologists blinded to HPV and HIV status reported cytologic results by Bethesda classification.ResultsMean age was 27.2 years (range 18–54). Overall, 86 (43.0%) had ASIL: 28 (14.2%) with atypical cells of undetermined significance (ASCUS), 1 (0.5%) with atypical squamous cells—cannot exclude high-grade squamous intraepithelial lesion (ASC-H), 56 (28.4%) with low-grade squamous intraepithelial lesion (LSIL), and 1 (0.5%) with high-grade squamous intraepithelial lesion (HSIL). ASIL was associated by univariate analysis (p ≤0.05) with older age, gender identity other than bisexual (i.e., gay men and transgender women), rectal douching, anal symptoms, genital warts, HIV positivity, and high-risk-HPV infection. However, on multiple logistic regression ASIL was associated only with high-risk HPV type (p = 0.002) and HIV infection (p = 0.01).ConclusionsASIL is quite common in high-risk MSM in northern Thailand and is associated with high-risk HPV types and HIV infection. Routine anal Pap screening should be considered, given the high frequency of ASIL, particularly in the HIV+. High resolution anoscopy (HRA), not done here, should be to confirm PAP smears whose sensitivity and specificity are quite variable. Timely HPV vaccination should be considered for this population.
Highlights
An increasing incidence of squamous cell cancer of the anus has been observed in diverse countries worldwide in the past couple decades [1] [2] [3]
We aimed to explore the prevalence of anal squamous intraepithelial lesions (ASIL) using Papanicolau (Pap) screening among men who have sex with men (MSM) in northern Thailand and its associated factors
ASIL and human papilloma virus (HPV) in MSM in Thailand had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Summary
An increasing incidence of squamous cell cancer of the anus has been observed in diverse countries worldwide in the past couple decades [1] [2] [3]. A number of strains of HPV (sometimes referred to as serotypes or genotypes when determined by serologic assay or genetic sequencing, respectively, but as types in this report) are considered high-risk for their association with various forms of cancer, for which the strength of that association for anal cancer is second only to that for the cervix in women [10]. The pathogenesis of both anal and cervical cancers are believed similar: starting with HPV infection, which after persistence induces low-grade lesions, which progress to high gradeintraepithelial lesions if spontaneous clearance does not occur, and eventually in some becoming invasive neoplasms [10] [11]. We aimed to explore the prevalence of anal squamous intraepithelial lesions (ASIL) using Papanicolau (Pap) screening among MSM in northern Thailand and its associated factors
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