(ChemotherapyAdvisor) – Anal human papillomavirus (HPV) and precursors of anal cancer are very common in men who have sex with men (MSM); however, a meta-analysis published in the Lancet Oncology online March 23 shows rate of progression to cancer is substantially lower than that for cervical precancerous lesions in women.

“Our findings mean that cervical cancer screening strategies cannot be simply extrapolated to anal cancer screening as current proposals suggest,” said Andrew Grulich, MBBS, MSc, PhD, University of New South Wales, Australia.

A systematic review and meta-analysis of 53 studies found that most men had anal HPV infection and high-grade anal intraepithelial neoplasia (AIN) was present in 20%–30%. Prevalence of infection with high-risk HPV types was substantially higher in HIV-positive men than in HIV negative men (73.5% vs. 37.2%), and precancerous abnormalities were also more common.

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An estimated 10% of HIV-positive men develop high-grade AIN annually compared with about 3% of HIV-negative men. “These incidence rates seem to be higher than would be consistent with our estimate of the prevalence of high-grade AIN (29% in HIV-positive MSM and 21% in HIV-negative MSM), unless many of these high-grade lesions regress,” the authors noted.

In this study, the progression rate from high-grade AIN to anal cancer was approximately 1 in 600 per year in HIV-positive men and 1 in 4,000 per year in HIV-negative men. High-grade cervical cancer precursors have a much higher rate of progression to cervical cancer, about 1 in 80 annually.

“The identification of biomarkers to establish which men with high-grade AIN are at highest risk for progression to anal cancer, and which are likely to regress, should be a research priority,” they noted. “Large, good-quality prospective studies are needed to inform the development of anal cancer screening guidelines for MSM.”