There is not enough evidence to support the idea that circumcision reduces the risk of HIV transmission between men who have sex with men, according to an article in the Oct. 8 issue of JAMA, the Journal of the American Medical Association, which references new analysis of previous research.

Sten H. Vermund, M.D., Ph.D., and Han-Zhu Qian, M.D., Ph.D., of Vanderbilt University School of Medicine said in an accompanying editorial that only future research can answer whether MSM should be circumcised to reduce their HIV risk.

“The meta-analysis by Millett et al is likely to be used by both advocates and detractors of clinical trial investment; some will argue the benefit is likely to be too modest to justify a multimillion dollar clinical trial while others will argue that only a clinical trial will answer this important HIV prevention question," wrote Vermund and Qian.

Randomized controlled trials (RCTs) conducted with men in Africa have shown that male circumcision reduces the likelihood of female-to-male transmission of HIV infection by 50 percent to 60 percent. Studies also suggest that male circumcision may protect heterosexual men against other sexually transmitted infections (STI), such as syphilis or chlamydial infection, according to background information in the article. Less is known about whether circumcision provides protection against HIV infection among men who have sex with men (MSM). 

Gregorio A. Millett, M.P.H., of the Centers for Disease Control and Prevention, Atlanta, and colleagues performed a meta-analysis of 15 studies to examine the association of circumcision status with HIV infection and other STIs among MSM. The studies included a total of 53,567 MSM participants (52 percent of whom were circumcised).

The researchers found that the odds of being HIV-positive were nonsignificantly lower among MSM who were circumcised than uncircumcised. In contrast, a statistically significant protective association of circumcision with HIV infection was found for MSM studies conducted prior to the introduction of highly active antiretroviral therapy (HAART) in 1996. Of studies conducted after HAART, the association of circumcision and HIV infection was not statistically significant.

“A possible explanation for [these differences] may be related to an increase in the sexual risk behaviors of MSM after HAART. It has been well documented that beliefs that HAART limits HIV transmissibility are associated with increases in sexual risk behavior among MSM, and that the era since the advent of HAART has been defined by higher rates of sexual risk behaviors among MSM, outbreaks of STIs, and increasing rates of HIV infection,” the authors write.

Among MSM who primarily engaged in insertive anal sex, the association between male circumcision and HIV was protective but not statistically significant. The STI analyses similarly revealed no statistically significant association by circumcision status among MSM.

“Taken together, these findings indicate insufficient evidence among available observational studies conducted with MSM of an association between circumcision and HIV infection or other STIs,” the researchers write. “Additional studies are necessary to elucidate further the relationship between circumcision status and HIV infection or STIs among MSM.”