Anal Cancer Screening Guidelines for PLHIV
Last updated: November 2024
Anal HSIL treatment
For biopsy-proven HSIL of the anal canal or peri-anus, active treatment has been shown to significantly reduce the incidence of progression to invasive ASCC in PLHIV10. Treatments should aim to eradicate, attenuate, or control disease, while minimising disturbance of normal anorectal function. Indiscriminate wide local excision is therefore no longer recommended, due to the high rates of complications such as anal stenosis and faecal incontinence. Current treatment options include HRA-guided lesional ablation, and local topical therapies. Clinicians may initiate treatment based on the first HRA and biopsy that confirms HSIL, although discretion may be exercised in individuals with a low risk of progression.
A. Ablative treatments
Local ablative therapy involves targeted destruction of HSIL lesions with protocols developed for modalities such as electrocautery (also known as hyfrecation)40 laser41, or infrared coagulation42-43. The ANCHOR study, which reported a 57% decline in cancer risk, was based on these ablative treatments (mostly electrocautery). Because the anal canal and peri-anus represent a field of change with respect to HRHPV exposure, targeted ablative techniques such as electrocautery have been shown to have recurrent/persistence rates in excess of 50%44. High-risk patients must therefore be counselled that they will be treated within a chronic disease framework, with close follow-up and the likelihood of repeated treatments. In general, it is advisable that patients resume their prescribed screening program 6 months after an initial ablative treatment, unless symptoms intervene. If cleared of HSIL on two consecutive occasions, they may be able to revert to their standard screening intervals.
B. Topical treatments
The treatment protocols available for topical agents generally have comparable efficacy to the ablative therapies for intra-anal and peri-anal disease clearance45-46. Given the issues surrounding self-application and their common side-effects, topical treatments are largely confined to perianal disease. Trichloroacetic acid has been shown to have reasonable efficacy with minimal side-effects when applied directly to two or fewer lesions under HRA guidance47; however, it is less effective for bulky lesions and more than one application is typically required to achieve remission. 5-fluorouracil48, cidofovir49, and imiquimod50 can all be self-applied by patients, although compliance is often an issue due to the high incidence of side effects such as skin irritation and anal burning sensation on defaecation. These agents also have the advantage of not being dependent on HRA guidance. However, because of the non-targeted nature of topical application, they are generally used to “downstage” rather than eradicate extensive disease to make it more amenable to eventual ablative treatment.
C. HPV Vaccination
HPV vaccination is not approved as a therapeutic agent for anal HSIL. There is conflicting evidence regarding its efficacy as an adjuvant following HSIL treatments to prevent or minimise recurrence51-54. Post-treatment vaccination to prevent future HPV infection, particularly with HPV1655, may nevertheless be discussed with patients, on the understanding that vaccination is not Medicare-funded for people older than 25 years. In people who test negative to HPV16, consideration should be given to vaccination, due to the possibility of new infection, while once again noting that the vaccine is not funded in this age group for men or women.
D. General advice
It should be noted that some patients will enter a screening protocol having already been diagnosed and/or partially treated for their HSIL, such as by a surgeon performing haemorrhoidectomy or a gastroenterologist noting lesions on retroflexion of the colonoscope. In such cases, clear excision margins on histology do not preclude the need for full HRA as multifocal disease is common.
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