High-grade squamous intraepithelial lesions (HSIL) and anal cancer are rising in incidence and at highest risk are HIV positive men who have sex with men (MSM). This pilot study assessing anal function and patient-reported outcomes before and after laser ablation of HSIL will add to the evidence that such a therapy is an acceptable and safe treatment to offer in a preventative setting.We will be recruting HIV positive and negative MSM.

High resolution anoscopy with targeted laser ablation is one of the therapies currently employed to treat HSIL of the anus to prevent progression to anal cancer. The functional outcome of this procedure has not previously been formally assessed.

HIV and negative positive MSM in whom HSIL has been detected will form the study population, as HSIL is prevalent in these patients and intervention is felt to be indicated. Functional assessments will be carried out prior to initial treatment and then repeated six months after laser ablation therapy. The structure, function and sensitivity of the anal canal will be evaluated using endoanal ultrasound, high-resolution anal manometry and anal mucosal electrosensitivity measurements respectively. Patient-reported outcomes will be assessed using questionnaires and semi-structured interviews at baseline, 4 weeks and 6 months post-treatment.

Inclusion Criteria:

MSM >18 years of age if HIV positive, CD4 count of over 350; if less, been on highly active antiretroviral treatment for at least 3 months Histologically proven high-grade squamous anal intraepithelial neoplasia lesion (HSIL) Anal canal disease with or without perianal disease Written informed consent

Exclusion Criteria:

Previous laser or other ablative treatment for HSIL (previous topical treatment is not excluded) Any treatment for HSIL in the previous six months Previous or current diagnosis of anal cancer Concurrent or previous (if severe) perianal inflammatory bowel disease, complex fistula or other significant perianal condition requiring surgery including fissures, current fistula in ano and Grade III or IV haemorrhoids Perianal sepsis Perianal disease only without anal canal HSIL