Anal cancer: 1 in 5 risk of missing precancerous lesions if only HSIL are biopsied
Simon Collins, HIV i-Base
A poster from researchers at the AIDS Clinical Center in Shinjuku-ku, Japan identifies a high risk of missing precancerous lesions due to the current approach to only biopsy lesions that are judged as HSIL after high-resolution anoscopy (HRA). 
From June 2021 to September 2022, the group reanalysed samples from 673 lesions from 122 individuals using sextant biopsies.
This collected at least six lesion samples in all directions regardless of abnormal findings from HRA.
The prevalence of HSIL was 81.3%(91/112) for individuals and 43.5%(293/673) for lesions.
The rate of the biopsy-proven HSIL that was predicted as LSIL was 36.5%(107/293) for each lesion and 19.8%(18/73) for each individual.
The authors concluded that approximately 1 in 5 HSIL cases were considered low-risk lesions based on their appearance and that these results might explain cases of recurrence after treatment.
A prospective, longitudinal Spanish study in 493 gay men living with HIV reported an approximate 5% annual risk of progression from low- to high-grade lesions over a median of 43 months (IQR:12 to 76) follow-up between May 2010 and December 2021. 
Risk factors for progression included acquiring high-risk HPV genotypes (HR: 4.15; IC 95%: 1.14 to 15.03), low-risk HPV genotypes (HR: 3.68 IC95%: 1.04 to 12.94), in particular genotype 6 (HR:4.47, IC95%: 1.34 to 14.91) and history of AIDS (HR: 5.81, 95%CI: 1.78 to 18.92).
This study shows the importance of biopsy for any suspected lesion – and that it is essential even when a lesion might look harmless.
Some services might have even higher rates of false negative results depending on the experience of the anoscopist.
Currently, however, the lack a proper screening service in the UK means that most cases of HSIL are not being detected.
The US CDC are planning to updated guidance and will be interesting to see their recommendations for DARE +/– anal cytology +/– hrHPV testing, and at what ages in different populations.
- Ando N et al. Standard biopsy with high-resolution anoscopy could miss potentially precancerous lesions. IAS 2023, poster abstract EPB0135.
Tenorio CH et al. Role of low-risk HPV PCR in screening for HSIL lesions and anal cancer in men who have sex with men (MSM) living with HIV (MSM-LWHIV). IAS 2023, poster abstract EPB0129.