FRIDAY, March 23 (HealthDay News) -- Anal human papillomavirus (HPV) infection and precancerous lesions are common among gay and bisexual men, but most of these cases will not progress to anal cancer, a new analysis of earlier research shows.
The researchers also found that the rate of progression from anal lesions to anal cancer among men appears to be much lower than the rate of progression from cervical lesions to cervical cancer among women.
Types HPV 16 and HPV 18 cause 80 percent of anal cancers and 70 percent of cervical cancers, according to background information in the report, published online March 22 in The Lancet Oncology.
In the study, the researchers analyzed data from 53 previous studies involving gay and bisexual men and found that most of the men had anal HPV infection, and 20 percent to 30 percent of them had precancerous anal lesions.
HIV-positive men were much more likely to be infected with high-risk HPV types than HIV-negative men (73 percent vs. 37 percent) and were also more likely to have precancerous anal lesions, the investigators noted.
The progression rate from high-grade anal lesions to anal cancer was about one in 600 per year for HIV-positive men and about one in 4,000 per year for HIV-negative men. In comparison, the progression rate from high-grade cervical lesions to cervical cancer is about one in 80 per year.
Because cervical cancer screening has led to sharp decreases in cervical cancer cases and deaths, it's been suggested that the same screening strategies for precancerous anal lesions in gay and bisexual men could save many lives. However, these findings indicate it's not that simple, lead author Andrew Grulich, of the University of New South Wales in Australia, explained in a journal news release.
"The substantial differences in the natural history of anal HPV infection to those of cervical HPV infection that this review has identified suggests that we cannot simply transfer cervical cancer screening strategies to anal cancer screening," Grulich and colleagues concluded.
"Large, good-quality prospective studies are needed to inform the development of anal cancer screening guidelines for [men who have sex with men]," the authors suggested.
SOURCE: The Lancet Oncology, news release, March 22, 2012