Promising outcomes from laser ablative treatment of AIN2/3 to prevent anal cancer

Simon Collins, HIV i-Base

The incidence of anal cancer is higher in HIV positive compared to negative populations with lower rates of clearance (87% vs 38% at 5 years) and progression rates from high-grade anal intraepithelial neoplasia (AIN 2/3) in observational studies range from approximately 8-14% over 5 years.

Thornhill and colleagues reported on retrospective results (median 69 months follow-up, range 36-180 months) from treating 91 patients (35 AIN 3; 56 AIN 2) with laser ablative treatment at Homerton Hospital in east London. [1]

Most patients were male (82/91) and MSM (80/82). Mean age was 36.9 (range 20-68). Of the 56 HIV positive patients, 66% (n=37) had a CD4 nadir of <200 cell/mm3. 45% (25/56) had been HIV positive for 15 years or more.

None of the patients in this cohort developed anal cancer suggesting that treatment may have prevented lesion progression in some patients.

The single case of anal cancer in this cohort, not included in this analysis follow-up was less than 3 years was a 49 year-old man (HIV positive for 21 years) with a CD4 nadir of 8. He had advanced 3 quadrant AIN 3 disease that presented late.

A second poster reported prospective first year results from a new ano-rectal outpatient clinic for HIV positive patients at the Royal Free Hospital. [2]

This is a monthly clinic for patients with a history of anal warts or previously diagnosed AIN. Symptomatic patients are screened by anoscopy +/- (surgical) evaluation under anaesthesia (EUA) where indicated. Patients were referred by their clinic doctor or self referred through promotion throughout the clinic.

Data was compiled from 73 patients seen over 12 months. Median (IQR) demographics included: age 45 years (IQR 41-50) years, 91% were MSM (67/73), 85% Caucasian (61/73). 95% (69/73) were on ART, 82% (60/73) with undetectable viral load. CD4 at presentation and CD4 nadir were 511 (362-741) and 152 (26-288) cells/mm3 respectively. Median time since HIV diagnosis was 15 years (10-20), with 11(6-13) years on HARRT. 75% (55/73) were smokers.

Anoscopy +/- EUA for screening was undertaken for 40% (30/73). Of these 27% (8/30) were diagnosed with AIN: AIN-1 (3), AIN-2 (2), and AIN-3 (3). 3/8 had prior diagnosis of AIN, the remainder were all newly diagnosed. 3/30 (10%) were diagnosed with ASCC and were managed by the surgeons and oncologists.

The clinic plans to expand the service to include a screening clinic specifically targeting all HIV positive, MSM who are >40 years, or have low CD4 nadir, or HIV infection > 10 years to undergo routine screening for AIN with Human Papilloma Virus (HPV) cytology, HPV typing and baseline anoscopy.


Greater awareness of AIN in HIV positive gay men, easier access to screening and the necessary support to diagnose complications is important.

The variable progression rates, lack of natural history data and recent availablility of effective treatments all highlight the urgent need for randomised data for the benefit of screening.


  1. Thornhill J et al. Treatment of anal intraepithelial neoplasia and prevention of anal carcinoma. 18th BHIVA Conference, 18-20 April 2012, Birmingham. Poster abstract 64. Download poster.
  2. Grover D et al. Anal intraepithelial neoplasia: single centre experience. 18th BHIVA Conference, 18-20 April 2012, Birmingham. Poster abstract 68. Download poster.

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