Early detection of anal squamous cell carcinoma with the use of high resolution anoscopy.

Background: In the UK, few (12%) anal squamous cell carcinomas (aSCC) are diagnosed early at stage 1 (T1N0M0). The Homerton Anogenital Neoplasia Service (HANS) is a highly specialised tertiary centre where high resolution anoscopy (HRA) is performed to diagnose and treat anal intraepithelial neoplasia (AIN), a precursor to cancer. In some cases, aSCC (here defined as anal canal cancers and perianal cancers up to 5cm from the anal verge) is found on referral for AIN; in others, aSCC may develop while undergoing AIN management.