14th Annual Conference of the British HIV Association 23-25 April 2008, Belfast

VALIDATION OF ANAL CYTOLOGY IN THE UK

HIV Med 2008 Apr 23-25 (Suppl 1);14:6 (abstract no. O23)

M Nathan¹, N Garrett¹, N Hickey¹, T Prevost², M Sheaff³ and N Singh^3
1 Homerton University Hospital, London, UK, ² University of Cambridge, Cambridge, UK, ³ Barts & The London NHS Trust, London, UK

BACKGROUND: High rates of anal squamous carcinoma have been identified in HIV+ MSM on HAART in London. No systematic screening for anal cancer precursors exist in the U.K. We looked at the validity of liquid-based cytology (smear) for screening amongst a high-risk population in London.

METHODS AND RESULTS: A total of 327 smears were evaluated from 233 patients (227 males). Median age of the population was 37 (IQ range 31- 43). Compared to histology, the sensitivity of smear for detecting any disease was 81% (95% CI 73%, 87%) with a PPV of 93% (95% CI 86%, 97%). Anal smear showed a sensitivity of 75% (95% CI 67%, 82%) and a PPV of 67% (95% CI 59%, 74%) compared to High Resolution Anoscopy examination findings. In 191 patients attending for assessment of cure after treatment, the sensitivity of smear for detecting recurrent disease was 70% (95% CI 49%, 86%) with a PPV of 83% (95% CI 61%, 95%). Overall, the sensitivity of anal cytology for detecting high-grade disease (AIN 2 and 3) was 89% (95% CI 75%, 96%) with a negative predictive value of 91% (95% CI 78%, 97%). Sensitivity of anal cytology was 89% in HIV+ men compared to HIV negative men (69%, p<0.01). In patients with the volume of disease reflecting one quadrant or less the sensitivity was much lower (56%) compared to those with two or more quadrant disease (>87%, p<0.001). Sensitivity of the smear was not affected by age or smoking.

CONCLUSIONS: Our results favour the use of anal cytology as a screening tool for HPV-related anal disease in high-risk populations. We further demonstrate its use in the follow-up of patients, after treatment of anal cancer precursor disease.

2008-04-23
O23

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