Self-collected versus clinician-collected anal swabs for anal cancer screening: A systematic review and meta-analysis.

Abstract

Anal squamous cell carcinoma (ASCC) incidence is increasing globally. International consensus guidelines published in 2024 include HPV and/or cytology testing of anal swabs in those at greatest risk of ASCC. Self-collected anal swabs may be important for increasing screening uptake, but evidence is needed as to their equivalence to clinician-collected swabs. We searched Medline, Embase, Cochrane Library, and CINAHL databases for publications to 13 June 2023. Studies were included if reporting data on HPV testing, cytology testing, or acceptability, for both self- and clinician-collected anal swabs. Risk of bias was assessed using the QUADAS-2 assessment tool. The primary outcome was HPV and cytology sampling adequacy. Secondary outcomes were HPV and cytology results, and acceptability of collection methods. Thirteen papers describing 10 studies were eligible. Sample adequacy was comparable between self- and clinician-collected swabs for HPV testing (meta-adequacy ratio: 1.01 [95% CI 0.97-1.05]) but slightly lower for cytology by self-collection (meta-adequacy ratio: 0.91 [95% CI 0.88-0.95]). There was no significant difference in prevalence (meta-prevalence ratio: 0.83 (95% CI 0.65-1.07) for any HR-HPV, 0.98 (95% CI 0.84-1.14) for any HPV, and 0.68 (95% CI 0.33-1.37) for HPV16), or any cytological abnormality (meta-prevalence ratio 1.01 [95% CI 0.86-1.18]). Only three papers reported acceptability results. Findings indicate self-collection gives equivalent sample adequacy for HPV testing and ~ 10% inferior adequacy for cytological testing. Meta-prevalence was similar for HPV and cytology, but confidence intervals were wide. Larger studies are required to definitively assess use of self-collected swabs in anal cancer screening programs, including acceptability.