The data come from a study in Uganda that already has shown circumcision effective in reducing a man's risk of HIV infection from heterosexual sex. The two-year study by Johns Hopkins researcher Aaron A.R. Tobian, MD, PhD, and colleagues enrolled nearly 3,400 men negative for HSV-2, the genital herpes virus.
"These findings ... indicate that circumcision should now be accepted as an efficacious intervention for reducing heterosexually acquired infections with HSV-2, HPV, and HIV in adolescent boys and men," the researchers conclude. "However, it must be emphasized that protection was only partial, and it is critical to promote the practice of safe sex."
The study did not show whether circumcision has any effect on homosexual transmission of HIV or other sexually transmitted diseases (STDs).
Some studies have suggested that circumcised men may be at lower risk of syphilis, but the Tobian study found no evidence to support this. Syphilis rates in the study were similar in both circumcised and uncircumcised men.
Nevertheless, circumcised men in the study had fewer genital ulcers.
How can circumcision prevent STDs? In at least three ways:
- When the foreskin is removed, the skin covering the head of the penis becomes tougher. That may protect against "microtears" during sex that can provide a point of entry for germs.
- The mucosal lining of the foreskin may allow germs to penetrate to underlying skin cells.
- After sex, the foreskin may prolong the time that tender skin is exposed to germs.
Circumcised men may be protecting their sex partners as well as themselves, suggest University of Washington researchers Matthew R. Golden, MD, MPH, and Judith N. Wasserheit, MD, MPH, in an editorial accompanying the Tobian study.
Data from earlier studies indicate that monogamous women with circumcised sex partners are only half as likely to get cervical cancer as are women with uncircumcised sex partners. And the Tobian study shows that circumcision cuts the risk of HPV, the virus that can cause cervical cancer.
Golden and Wasserheit suggest that access to safe circumcision -- both for adults and for newborns -- should be provided in all areas with a high prevalence of heterosexual HIV transmission.
In the U.S. circumcision policies are being reviewed. The American Academy of Pediatrics is looking at whether there is sufficient evidence to recommend routine neonatal circumcision.
"In the United States, rates of circumcision are declining and are lowest among black and Hispanic patients, groups in whom rates of HIV, herpes, and cervical cancer are disproportionately high," Golden and Wasserheit note.
The Tobian study, and the Golden/Wasserheit editorial, appear in the March 26 issue of The New England Journal of Medicine.