Anal cancer screening for people living with HIV gained support following the phase 3 ANCHOR randomized trialdemonstrated that treating high-grade squamous intraepithelial lesions significantly reduced cancer risk. These findings shaped 2024 guidelines recommending routine screening in high-risk groups.
Anal cancer accounts for about 10,000 cases annually in the US and more than 50,000 globally. Risk is disproportionately higher among people with HIV (PWH). Incidence among men who have sex with men (MSM) is 85 per 100,000 person-years, compared with 1 to 3 per 100,000 in the general population.
The ANCHOR trial enrolled 4,446 adults with HIV aged 35 years or older with biopsy-confirmed high-grade squamous intraepithelial lesions (HSIL). Participants were randomized to treatment—most often by electrocautery ablation—or active monitoring. After a median follow-up of 26 months, anal cancer developed in 0.9% of the treatment group compared with 1.8% in the monitoring group, a 57% relative reduction. The trial was stopped early after 33 cases were confirmed, meeting the predefined threshold for treatment efficacy. Mortality outcomes were not evaluated.
Serious adverse events were reported in 31 participants in the treatment group (1.4%) and included anal pain, bleeding, and stricture; no procedure-related deaths occurred.
In response, the U.S. Department of Health and Human Services and the International Anal Neoplasia Society issued new guidelines now recommend routine anal cancer screening beginning at age 35 for MSM and transgender women with HIV, and at age 45 for other men and women with HIV. Screening includes an anal cytology with or without high-risk human papillomavirus (HPV) co-testing, plus digital anorectal examination, with abnormal results confirmed by high-resolution anoscopy.
“The field of anal cancer prevention among PWH is at an inflection point with promising early data and now delineated clinical guidelines,” said Hayden S. Andrews, MD, of the Division of Infectious Diseases and Geographic Medicine at the University of Texas Southwestern Medical Center, and colleagues.
HPV, particularly type 16, is implicated in the majority of anal cancer cases. Vaccination prior to exposure is effective in preventing infection and dysplasia, though evidence has not shown a reduction in HSIL recurrence. Available treatments HSIL include electrocautery ablation and topical agents such as fluorouracil, imiquimod, and cidofovir. No therapy is currently approved by the U.S. Food and Drug Administration specifically for HSIL. Ongoing questions include long-term mortality outcomes, optimal screening intervals, and access to high-resolution anoscopy
Full disclosures can be found in the published study.
Source: Clinical Infectious Disease
