While uncommon in the general population, the incidence of anal squamous cell carcinoma (ASCC) is increasing, and certain groups, including people living with HIV (PLHIV) are disproportionately affected^1-2. While anal cancer can affect people of all ages, unlike cervical cancer, rates do not start rising until 35 years or older and continue to rise with increasing age³.

High risk human papillomavirus (HRHPV) can be detected in 88% of ASCC. Approximately 90% of ASCC is caused by HPV16 in the general population, whereas in PLHIV, 70% are caused by HPV16. This places ASCC second only to cervical cancer in the strength of its association with HPV infection3. ASCC is one of the most common non-AIDS defining cancers in people living with HIV in Australia^{4 5}, a finding also reported in other developed countries with similar HIV epidemics^6-8.

Cervical cancer screening uses a modifiable, evidence-based approach, basing management recommendations on the current understanding of HPV natural history and carcinogenesis⁹. The effectiveness of cervical cancer screening in reducing cervical cancer incidence relies on the successful treatment of the cancer precursor, high-grade squamous intra-epithelial lesion (HSIL).” Until recently, similar approaches for anal cancer screening have been impeded by the lack of evidence of anal HSIL treatment efficacy and there being no identified anal cancer screening test with both high sensitivity and specificity. The results of the Anal Cancer/HSIL Outcomes Research (ANCHOR) randomised trial published in 2022 showed that treating HSIL that had been identified through screening, reduced anal cancer incidence in PLHIV in the US by 57% compared with active monitoring alone. ANCHOR reported an anal cancer incidence of 402 per 100,000 person years among participants in the active monitoring (no treatment) arm¹⁰. A survey conducted by the US Centres of Disease Control in 2019 reported that less than 5% of PLHIV received screening for ASCC despite their significantly higher risk¹¹. In Australia, it is recommended that PLHIV receive an annual digital ano-rectal examination (DARE) and examination of the peri-anal area to detect early anal cancer lesions¹². However, until now, screening for anal and peri-anal cancer precursors has not been recommended. Early detection of ASCC has been demonstrated to improve treatment outcomes and reduce mortality rates¹³ and cancers identified early can be treated with local excision only, if adequate excision margins are obtained¹⁴. Anal cancer survival is closely related to tumour size at presentation, spread to local lymph nodes, and presence of distant metastases. Five-year survival ranges from 85.5% when diagnosed at stage I (small size, no evidence of spread), to 22.1% when diagnosed at stage IV¹⁵. Significant toxicity occurs with chemoradiotherapy, the recognised standard of treatment for ASCC. Based on the ANCHOR findings, mathematical modelling has estimated that the implementation of annual HSIL screening and treatment in gay, bisexual and other men who have sex with men (GBM) living with HIV would lead to a decline of 44-70% in ASCC incidence¹⁶.

In 2024, the International Anal Neoplasia Society (IANS) consensus guidelines for anal cancer screening were published. These recommend that GBM and trans women living with HIV should be screened annually from the age of 35 years. They also recommend that all other people living with HIV (women, men who have sex with women) should be screened annually from the age of 45 years¹⁷.

In July 2024, the first ever US Department of Health and Human Services (DHHS) guidelines for anal cancer screening in PLHIV were released, incorporated in the Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents with HIV¹⁸.

The guidelines recommend that all people with HIV aged 18 years or older be assessed for anal abnormalities and undergo DARE at least once per year. PLHIV aged less than 35 years with symptoms/signs of anal cancer during DARE are recommended to undergo standard anoscopy. Screening with anal cytology (+/- high risk HPV testing) with subsequent high resolution anoscopy (HRA) is recommended for GBM and trans women aged 35 years and older and for all other PLHIV aged 45 years or older¹⁸.

In light of the elevated risk of anal cancer in PLHIV, established evidence that treating anal HSIL reduces the incidence of ASCC in PLHIV, and the publication of international guidelines, there is a clear need for Australian guidelines for regular screening and early detection of anal cancer in PLHIV. The Australasian Society for HIV Medicine, Viral Hepatitis and Sexual Health Medicine (ASHM) is the peak professional body representing healthcare professionals in HIV, blood-borne viruses (BBV), and sexual and reproductive health. In 2023, ASHM committed to providing recommendations and standards of care for the prevention and early detection of anal cancer in PLHIV. To develop consensus guidelines for ASCC prevention and early detection, ASHM assembled a Guidelines Committee of 14 community, clinical, research, and laboratory representatives with a wide range of professional expertise, including epidemiology, prevention, pathology, sexual health, health promotion, community engagement, colorectal surgery, HRA, and advocacy. A subset of the committee (the Writing Group) was convened to draft guidelines with assistance and overview from ASHM staff and the Guidelines Committee. The Writing Group consisted of five people with expertise in ASCC screening and treatment and working with PLHIV and community expert(s) representing key affected populations. The finalised guidelines were approved by the ASHM Guidelines Committee and the ASHM National Advisory Group for HIV and STIs.

The four priority areas for guidelines development in Australia were: (1) establish the ASCC incidence in PLHIV to substantiate the benefits of screening in this population, (2) ASCC screening tools and testing algorithms, (3) management of screening results and (4) treatment of anal HSIL. The recently published IANS consensus guidelines for ASCC screening and US DHHS recommendations form the basis of Australia-specific recommendations.