High-Risk Human Papillomavirus Prevalence and Detection of Anal Intraepithelial Neoplasia in Women Undergoing Screening Colonoscopy: A Prospective Study.

The incidence of anal cancer in older women has risen significantly in recent decades, yet no standard screening strategy exists. Screening aims to detect potentially precancerous lesions, anal intraepithelial neoplasia (AIN), which can be treated to prevent cancer progression. In this prospective study, we assessed the prevalence of high-risk human papillomavirus (hrHPV), abnormal anal cytology, and AIN confirmed by high-resolution anoscopy (HRA)-guided biopsy. Women aged ≥ 40 undergoing routine screening colonoscopy in Cologne, Germany, were enrolled. Before colonoscopy, anal samples were collected for hrHPV testing and cytology. Participants with positive hrHPV and/or abnormal cytology underwent HRA with biopsy and treatment if necessary. Among 483 women (November 2023-March 2025), hrHPV was detected in 78 (16.1%), while cytological abnormalities were found in only 6 (1.2%). In hrHPV-positive women, HRA identified low-grade squamous intraepithelial lesion (LSIL) in 11 (14.1%) and high-grade squamous intraepithelial lesion (HSIL) in 6 (7.7%); all lesions were treated with argon plasma coagulation. Anal symptoms (bleeding, pain, or pruritus) were associated with hrHPV positivity (adjusted PRR: 1.72; p = 0.023). Among hrHPV-positive participants, infection with multiple hrHPV types was linked to AIN (adjusted PRR: 2.90; p = 0.017). In conclusion, hrHPV prevalence was relatively high, while cytology alone showed limited sensitivity for detecting AIN. Identification and treatment of high-grade lesions, potentially precursors to anal cancer, suggest that screening could help prevent disease progression and support incorporating anal hrHPV testing into preventive strategies for women.