Does use of anal cytology as a triage test improve the performance of high-risk human papillomavirus screening in gay and bisexual men for anal cancer prevention?

Anal high-risk human papillomavirus (HRHPV) testing-based anal cancer screening gay and bisexual men (GBM) is associated with high sensitivity, but low specificity. We report the potential role of triage use of anal cytology with HRHPV testing in detecting 12-month persistent anal high-grade squamous epithelial lesions (HSIL) in a cohort of GBM in Sydney, Australia. Participants were GBM from the Study of the Prevention of Anal Cancer (SPANC) who underwent annual anal HPV testing, cytology, and high-resolution anoscopy (HRA)-guided histology. The sensitivity and specificity of five screening algorithms based on HRHPV test results with triage use of anal cytology (atypical squamous cells of undetermined significance (ASCUS) and atypical squamous cells, cannot exclude HSIL (ASC-H) used as referral thresholds) were compared to these of HRHPV testing and anal cytology alone. A total of 475 men who had valid HRHPV, cytological, and histological results at both baseline and first annual follow-up visits were included, median age 49 years (inter-quartile range: 43-56) and 173 (36.4%) GBM with human immunodeficiency virus. Of all triage algorithms assessed, two had comparable sensitivity with HRHPV testing alone in detecting persistent anal HSIL, but ~20% higher specificity and 20% lower HRA referral rates. These two algorithms involved the immediate referral of those with HPV16 and for those with non-16 HRHPV either immediate or delayed (for 12 months) referral, depending on cytology result at baseline. Triage use of anal cytology in GBM testing positive for anal HRHPV increases specificity and reduces referral rates while maintaining high sensitivity in detection of HSIL.