Prevalence of anal HPV infection and anal HSIL among MSM 50 years and older living with or without HIV

Background: Anal cancer is caused by human papillomavirus (HPV), particularly HPV-16, and is preceded by anal high-grade squamous intraepithelial lesions (HSIL). The incidence of anal cancer is highest among men who have sex with men (MSM) living with HIV (MSMLWH) and increases with age. However, most previous studies of anal HPV infection and anal HSIL were performed on men under 50 years of age, and relatively little is known about HSIL among older MSMLWH or MSM not living with HIV (MSM-Not-LWH). Setting: We enrolled MSM who were aged 50+ during 2018-2022 in San Francisco, California. Methods: 129 MSMLWH and 109 MSM-not-LWH participated. All participants had anal HPV DNA testing (Atila Biosystems) and high-resolution anoscopy with biopsy of visible lesions. Results: Among MSMLWH, 47% had anal HSIL, 19% had HPV-16, and 51% had other oncogenic anal HPV types (excluding HPV-16). Among MSM-not-LWH, 37% had anal HSIL, 22% had HPV-16, and 34% had other oncogenic anal HPV types. Increasing age was not statistically associated with prevalent HSIL, HPV-16, or other oncogenic HPV infections in MSMLWH or MSM-not-LWH. HPV-16 (OR:45.1, 95% CI:15.8-129), other oncogenic HPV types (OR:5.95, 95% CI:2.74-12.9) were associated with increased odds of anal HSIL, adjusted for age, income, education, and HIV status. Conclusion: The prevalence of oncogenic anal HPV, anal HPV-16, and anal HSIL remain very high in older MSMLWH and MSM-not-LWH. With recent evidence showing that treating anal HSIL prevents anal cancer, MSM aged 50+ should be considered for anal cancer screening.