Here, Joel Palefsky, MD, a professor of laboratory medicine at UCSF who has done research on anal cancer, discusses the anal Pap smear and biopsy of POZ contributing editor Stephen Gendin.

HIV positive gay and bisexual men appear to be at twice the risk for developing potentially fatal anal cancer than are their HIV negative brothers. And the numbers are growing. Because screening can identify those at highest risk, Stephen Gendin decided to visit Stephen Goldstone, MD, a New York City surgeon and expert on gay men’s health, for an anal Pap smear.

Similar to the Pap smear that women have done to look for evidence of cervical cancer (or pre-cancerous changes), this test can identify cell changes called anal squamous intraepithelial lesions (ASIL). A high-grade ASIL may lead to cancer, although no data exist about the speed of progression.

In a four-year study that my colleagues and I published last year, more than half of the HIV positive gay and bisexual men who initially had fewer than 500 CD4s—and a third who had more than 500 CD4s—developed high-grade anal lesions. For this reason, I recommend that all HIV positive men who have sex with men have annual anal exams—both a visual inspection and a Pap smear. Since the primary risk factor is receptive anal sex, even HIV negative gay men should have this done every two or three years. And although HIV positive women have been insufficiently studied, their risk of anal cancer may also be high, and similar screening recommendations may ultimately be made for them.

Stephen’s Pap smear found abnormal cells, so he then had a high-resolution anoscopy. In this procedure, a scope is put into the anus to inspect the source of the abnormal cells found on the Pap smear. Then biopsies—necessary to guide treatment decisions—are performed to confirm the grade of the disease.

Low-grade lesions require no treatment, but followup exams about every six months are crucial to guard against progression. In Stephen’s case, the biopsy found multiple high-grade squamous intraepithelial lesions. This is not evidence of cancer, but shows a serious spread of lesions. Such a finding would normally lead to surgery to clear areas with abnormal cells. But because Stephen has just resumed antiretroviral therapy (after months without), he and Dr. Goldstone are holding off on a decision about surgery until Stephen adjusts to the medications.

Many surgeons are not well-trained in these procedures, yet such training is key to obtaining successful results. Before either a biopsy or surgery, doctors should presoak the anal canal with a 3 percent vinegar solution. Magnification with a magnifying glass, colposcope or surgical loop (special glasses) will minimize the chances of missing any ASIL areas. Surgery is often followed by pain, constipation, discharge and minor bleeding for two or three weeks. Patients should be prescribed appropriate pain killers (including anesthetic lidocaine cream for local pain), stool softeners and sitz baths.

If cellular changes are not caught until there’s full-blown anal cancer, you’re talking about chemotherapy, radiation and possibly death. Even for those like Stephen in whom the condition has not progressed that far, treatment can be much more difficult than if the problem had been detected earlier through periodic Pap smears. Note that a negative Pap can simply mean that an anal lesion has been missed. Repeated testing at the recommended intervals improves the likelihood of getting accurate results and, if warranted, early treatment. And contrary to the common view, if a Pap smear is positive and the person also has anal warts, excising them may leave behind areas of ASIL, so a biopsy and followup are still required.

Unfortunately, only a few physicians—mostly those with large HIV practices—do anal Pap smears, although they are easy to perform and relatively cheap (under $50 to the patient). If you have a Pap smear done and abnormal cells are found, find a surgeon educated about the need to treat high-grade ASIL.

We know that cervical Pap smear screening dramatically reduces the rate of cervical cancer and death in women. Likewise, performing regular anal Pap smears in gay and bisexual men is lifesaving—and, according to a new study, cost-effective. My hope is that such screening will soon become the standard of care.