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BRISBANE, Australia -- Voluntary medical male circumcision appeared to protect men who have sex with men from acquiring HIV, especially those who primarily practice insertive anal sex, researchers from China reported here.

Of the 124 men assigned to undergo circumcision, there were no seroconversions during the 12 months of the randomized controlled trial, while five men among the 123 in the control group were infected with HIV (P=0.025), reported Huachun Zou, MD, of Sun Yat-Sen University in Shenzhen.

"This is the first randomized controlled trial to demonstrate the efficacy of voluntary male medical circumcision in preventing HIV among men who have sex with men," Zou said at the International AIDS Society Conference on HIV Science.

"Voluntary medical male circumcision is very likely to be efficacious in preventing incident HIV acquisition among men who have sex with men who predominantly practice insertive anal sex," he added, suggesting that a large-scale study may be needed to confirm these findings.

However, a larger trial may not be possible with the worldwide rollout of effective pre-exposure prophylaxis (PrEP) therapy. In this study, the men in China were not offered PrEP initially, but by 6 months into the year-long study, 3% to 5% of the participants told clinicians they had been taking PrEP.

"I think we should note that the abstract does not address whether the men were offered PrEP," said Charles Gilks, PhD, of the University of Queensland in Brisbane, in discussing this study during a press conference. "In any case, it's always good to have another prevention option. We anticipate that PrEP rollout will continue to be the priority in most settings. However, circumcision may continue to be augmented and added in terms of prevention."

He pointed out that three randomized controlled trials in southern Africa showed that voluntary medical male circumcision reduced transmission of HIV among heterosexual couples by 50% to 60%.

"And since then, voluntary medical male circumcision has been scaled up in many places as the prevention of HIV in heterosexual men," Gilks noted. "Modeling studies have estimated that circumcision has prevented hundreds of thousands of HIV infections to date, particularly in southern and eastern Africa."

"However, when it comes to men who have sex with men, there have only been observational studies," he added, "and those studies have in fact had quite mixed results."

"We think this study will attract a lot of interest because the results are so interesting, and this is the first time a randomized trial has looked at this in men who have sex with men, a key population for HIV prevention," he said.

To conduct the study, the researchers in eight cities in China recruited men ages 18 to 49 who self-reported at least two male sex partners in the previous 6 months, and who predominantly practice insertive anal sex. The men had to be willing to undergo circumcision. Interested men were tested for HIV 1 month before enrollment and at enrollment, and only those who remained HIV-negative were enrolled.

At baseline, all enrolled participants reported sociodemographic characteristics and sexual behaviors; provided a blood sample for HIV, syphilis, and herpes simplex virus 2 (HSV-2) testing; and provided a penile swab for human papillomavirus (HPV) testing.

Participants were randomly assigned to the intervention or control group. Those in the intervention group underwent voluntary medical male circumcision and a web-based weekly follow-up assessment of post-surgery healing for 6 consecutive weeks. All participants will be tested for HIV at 3, 6, 9, and 12 months. They will also report sexual behaviors and undergo repeat HSV-2 and HPV testing at 6- and 12-month follow-up.

The researchers have plans to follow the cohort to determine the long-term duration of circumcision's effects, but are awaiting additional funding, Zou said.

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