Nugent, Diarmuid; (2023) Human papillomavirus in men who have sex with men: evaluating the impact of opportunistic vaccine provision and improving treatment approaches for anogenital warts. Doctoral thesis (M.D(Res)), UCL (University College London).

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Abstract

Gay, bisexual and other men who have sex with men (GBMSM) are disproportionately affected by morbidity from sexually transmitted human papillomavirus (HPV) infection, especially anal/perianal warts and anal cancer. Opportunistic HPV vaccination for GBMSM was introduced in England from 2016. I address these key questions regarding HPV in GBMSM: • How do residual specimens from rectal sexually transmitted infection (STI) screens perform against anal swabs for HPV detection for surveillance monitoring the impact of the vaccination programme? • What treatment options are best for anal/perianal warts? • Are there correlates of successful response to anogenital wart (AGW) treatment and do outcomes for GBMSM differ from women and heterosexual men? In my cross-sectional study, 129 GBMSM provided anal swab specimens to be tested for HPV along with residual volumes of their rectal and pooled (rectal/oropharyngeal/urine) STI screen specimens; 71.3% had detectable genotype-specific HPV. Detection was highly concordant for all three specimen types. In my systematic review of randomised controlled trials of perianal/anal wart treatment, data from 18 studies supported the safety and efficacy of surgical excision/ablation, and the topical agents imiquimod and podophyllotoxin for external lesions, but no evidence supported superiority of any treatment. The HIPvac study compared imiquimod versus podophyllotoxin and quadrivalent HPV vaccine versus placebo to treat external AGW. In my sub-analysis, current/past smoking, a higher number of warts and penile warts were negatively associated with sustained clearance following treatment. While outcomes in GBMSM and non-GBMSM participants were similar, perianal warts were more likely to clear following vaccine, an effect not seen for warts at other anogenital sites. My research supports using residual STI screen specimens for HPV surveillance in GBMSM. The beneficial effect of vaccine for perianal warts is a novel finding and may reflect their less keratinised, more vascular composition making them more responsive to humoral immunity than AGW elsewhere.

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