People with HIV may have a heightened risk for developing anal lesions caused by human papilloma-  virus (HPV)—whether or not they've ever had anal sex. A Parisian study of HIV-positive volunteers found that 36 percent of heterosexual women and men, and about twice as many gay men, had anal lesions. It's believed that at least some of these lesions can eventually turn into anal cancer. While anal cancer is rare among negative people and generally develops slowly, it's more common among HIV-positive people.

While Centers for Disease Control and Prevention (CDC) experts take a conservative approach to routine yearly anal screening, a growing number of HIV specialists think that regular anal Pap smears—in which a cotton swab is rubbed against the anal wall and the sample is sent to a lab—may help identify people with high-grade lesions, allowing them to be watched more closely. “Ideally,” says Joel Palefsky, MD, of the University of California at San Francisco, “I think all HIV-positive people should have a Pap smear if possible. In the absence of the full [range of Pap and follow-up tests], everyone should have an annual digital rectal exam to feel for lesions that might be cancer.” Catching cancers early increases the chance for treat-ment success.

The first step: Ask your provider for a smear, a high-resolution scope or a digital exam. Once you establish your baseline risk, you'll know better how closely you should be monitored going forward.