Anal human papillomavirus infection and its relations with abnormal anal cytology among MSM with or without HIV infection in Japan

Background: Anorectal high-risk human papillomavirus (hr-HPV) infection is associated with anal malignancies. However, the epidemiological data is quite limited in Japan. Methods: Anorectal swab was obtained from HIV-infected and –uninfected men who have sex with men (MSM). Only high-risk HPV genotypes were examined by the Hybrid Capture-based methodology. Anal cytology was determined by the modification of the Bethesda System classification. Results: In total, 644 participants were included. No participant had history of HPV vaccination at inclusion. The overall prevalence of hr-HPV was 58.5% (95% confidence interval: 54.7-62.3). The most frequently detected hr-HPV genotypes in order were HPV-52, -16, and -58. Among the HPV infected subjects, 82.8% (312/377) were infected with at least one of the 9 valent vaccine covered genotypes. Incidence of abnormal cytology was positively correlated with the number of HPV genotypes infected rather than the difference in genotypes. Multivariate analysis identified the number of detected hr-HPV genotypes as well as HIV-infection were the independent risk factors for pre-cancer. Conclusion: Nine valent vaccine preventable HPVs are currently prevalent among MSM in Japan. Also, increased numbers of hr-HPV genotypes were strongly associated with anorectal pre-cancer. Universal HPV vaccination should be considered for Japanese MSM.