Saturday, October 6, 2007

Cutting Out HIV Risk through Circumcision - Is it an Option?

By Stephen J. Fallon, Ph.D.

Putting a condom on reduces your risk of catching HIV and some sexually transmitted diseases. Taking something off reduces risks, too. The something that comes off is foreskin.

No, this isn’t a plot synopsis for Nip and Tuck. Circumcising adult men reduces their susceptibility to HIV infection by a large enough margin that New York City’s Department of Health is considering promoting, and possibly even paying for the procedure. The United Nations has even developed a kit to teach doctors in developing nations how to perform a circumcision safely on adults.

Our skin is supposed to serve as our immune system’s first line of defense, a barrier that blocks most pathogens from getting inside of us. The foreskin is rich in Langherans cells, which are designed to help trigger a fuller antibody response before any topical infection can fester. Yet HIV thwarts this front line defense by riding in through the Langherans cells, and invading the main machinery of the immune system.

Lab experiments long ago suggested that foreskin seems to have a tendency to “soak up” HIV, and some other STDs. “Uncut” guys have lots of Langerhans cells in their foreskin. Circumcised guys only have some inside the urethra.

In February, the last of three real world studies confirmed exactly how much risk uncut men face when having unprotected sex. The study in Lancet randomly assigned 2,474 out of nearly 5,000 men to receive an adult circumcision. Checking back two years later, researchers found that men who had been circumcised had 55 to 60 percent lower HIV infection rates. The first study had put the risk reduction at 48 percent.

So should gay men in New York or any other city consider the sort of outpatient surgery that makes even butch men weak in the knees? Would circumcision help protect them from HIV and STDs? Let’s look at how circumcision might or might not help for gay men.

Tops are not invulnerable: Lots of gay men already believe that they can’t catch HIV as long as they only top. Studies do show that penetrating partners (“tops”) generally face much lower risks than penetrated partners (“bottoms”). The urethra presents a smaller “port of entry” for HIV than does the rectum.

Now here’s the catch: other factors can pretty much erase the relative safety of being on top. If the guy on bottom has an STD, or if the top has one, or if the bottom was very recently HIV infected, each of these influences will increase the risks for the top three times to twelve times higher, to nearly the same average risk level the bottom faces in unprotected sex. Even circumcision can’t protect tops from all of those risk amplifiers.

It’s not just about STDs: Since STDs amplify the ability to catch or transmit HIV, one old study famously suggested that it was genital ulcers, not foreskin, that caused higher HIV rates in some men. Take away the genital ulcer variable, the authors said, and circumcised guys are actually more prone to HIV.

This was a misleading study. The researchers did not personally examine any men, but instead counted numbers of past HIV infections in certain countries. The U.S. has higher HIV infection rates than, say, Israel or Mexico, where there are large numbers of uncircumcised men. So the authors concluded that circumcision made guys more vulnerable to HIV. Actually different risk trends in these countries explain the results.

A newer, more rational study in the journal Emerging Themes in Epidemiology proves that circumcision directly reduces HIV risk. While circumcised men also benefit from lower STD rates, the impact of this overlapping factor was much smaller than the direct protection against HIV that removing the foreskin offered.

Benefits for bottoms: Even though circumcision does not directly protect bottoms, to the extent that it might lower overall rates of HIV among tops, it could mean lower odds that a bottom would have an HIV infected top as his partner. A recent U.N. report notes this community protecting potential. Condoms are still a must if bottoming for a non-monogamous or untested partner. But if a condom breaks or is forgotten in the heat of the moment one night, your HIV risk might be lower if your top is circumcised.

Circumcision doesn’t protect against denial: The three major circumcision studies discussed here only looked at heterosexual males. Gay men would get the same 48 to 60 percent protection from HIV that circumcision offers, but only when they top. Now here’s the bad news: HIV doesn’t care if you’re “mostly top,” or built like a top (whatever that means), or were exclusively the top in your last relationship. Only your next unprotected sex matters.

Everyone knows versatile guys who claim to be total tops. Or, frankly, total bottoms who claim to be tops. Even if you do get circumcised to reduce your risks, any time you bottom without insisting on condoms, you’ll still be at the highest risk of getting infected.