[Anal cancer screening: who, how, and why?]

Although anal cancer remains rare in the general population, it is becoming more prevalent, particularly in high-income countries such as France, where the incidence rate is among the highest in the world. Over 90 % of anal cancers are caused by high-risk human papillomavirus (HR-HPV), particularly HPV16. Although two-thirds of cases occur in women, certain groups are at a higher risk, including men who have sex with men (MSM) living with HIV, women living with HIV, women with a history of high-grade vulvar lesions and patients who have received a solid organ transplant more than ten years ago. The ANCHOR randomised trial demonstrated for the first time that treating high-grade squamous intraepithelial lesion (HSIL) significantly reduces the risk of progression to anal cancer in people living with HIV, justifying the implementation of targeted screening strategies. Screening is primarily based on anal cytology and HR-HPV detection, with algorithms varying according to national and international recommendations. In France, a novel approach focusing on HPV16 detection aims to enhance specificity and reduce the reliance on high-resolution anoscopy (HRA), which is considered the gold standard but is not widely accessible. Anal self-sampling appears to be a significant factor in facilitating the implementation of screening, with analytical performance comparable to samples taken by clinicians. Despite ongoing debates about the risk-benefit ratio and cost-effectiveness of anal cancer screening, recent data support its value in high-risk populations. Improvements in triage algorithms, particularly through the use of methylation biomarkers, could optimise the referral of patients requiring HRA in the future and enhance the effectiveness of anal cancer screening by reassuring patients at lower risk of developing cancer. This article aims to provide an overview of the knowledge on which the various anal cancer screening recommendations are based, the means available for implementing this screening, and the obstacles to its implementation.