LAUSR

OBJECTIVES To investigate factors associated with larger burden of intra-anal high-grade squamous intraepithelial lesions (HSIL) in a natural history study of HSIL. METHODS 617 gay and bisexual men (GBM) attended a baseline visit. High-resolution anoscopy-directed biopsy was performed of suspected HSIL. GBM with biopsy-confirmed HSIL (bHSIL) affecting a single-octant were compared with those who had bHSIL affecting a larger area. RESULTS Of 196 men with bHSIL at baseline, 73 (37.2 %) had larger bHSIL burden. Larger burden was independently associated with anal HPV16 detection (aOR 2.06, 95 % CI 1.09-3.89, p = 0.026) and infection with a greater number of high-risk HPV types (aOR per type increase 1.25, 95 % CI 1.05-1.49, p-trend = 0.010). CONCLUSION The observation that men with a larger burden of HSIL also had more risk factors for anal cancer suggests this group may warrant closer observation to ensure earlier detection, and thus improved prognosis, of individuals whose HSIL may progress to anal cancer.