A prospective study of anal cancer screening in HIV-positive and negative MSM.

OBJECTIVE

The study sought to establish the feasibility and acceptability of anal screening among men MSM.

DESIGN

Prospective cohort study.

SETTING

Sexual health clinics in tertiary care.

PATIENTS

Known HIV-positive and negative MSM who have anoreceptive intercourse.

INTERVENTION

Anal screening with human papilloma virus (HPV) testing, liquid-based cytology and high-resolution anoscopy with biopsy of anoscopic abnormalities. Participants completed questionnaires at baseline and at 6 months.

RESULTS

Anal HPV was highly prevalent in MSM (HIV-positive, 88% and HIV-negative, 78%). Despite the high prevalence of cytological abnormality in both HIV-positive (46.2%) and negative (35.0%) MSM, almost half of anal intraepithelial neoplasia (AIN) of all grades were associated with negative cytology. Anoscopically directed biopsies detected AIN3 or worse (AIN3+) in 14 of 203 (6.9%) of HIV-positive MSM and three of 81 (3.7%) HIV-negative MSM. The corresponding prevalence of AIN2+ was 26.6 and 20.9%, respectively. One case of AIN3 was detected at the second visit. Screening was considered to be highly acceptable by participants.

CONCLUSION

The high prevalence of high-risk-HPV and frequency of false negative cytology in this study suggest that high-resolution anoscopy would have most clinical utility, as a primary screening tool for anal cancer in a high-risk group. The prevalence of AIN3+ in HIV-positive MSM lends support for a policy of screening this group, but the high prevalence of lower grade lesions which do not warrant immediate treatment and the limitations of treating high-grade lesions requires careful consideration in terms of a screening policy.