Kaiser Study Finds Higher Cancer Risk for HIV Patients

People with HIV have a higher risk of developing certain cancers than do uninfected individuals -- and the weaker their immune system, the more vulnerable they are to cancer, a large study of Kaiser Permanente members shows.

Researchers have long known HIV is associated with increased cancer risk, particularly virus-caused cancers such as Kaposi's sarcoma and non-Hodgkin's lymphoma. HIV attacks the immune system, making patients more vulnerable to other viruses and, in turn, cancer. But just how much of an increased risk has not been well understood, and scientists have struggled to separate the risk of cancer from the behaviors that can increase cancer risk and tend to be associated with HIV, including smoking, drinking, and having unprotected sex.

Study lead author Dr. Michael Silverberg, a research scientist with the Kaiser Permanente Division of Research in Oakland, compared cancer rates among 20,000 HIV-positive Kaiser members in California and 215,000 uninfected members. Higher rates of Kaposi's sarcoma, non-Hodgkin's lymphoma, Hodgkin's lymphoma, melanoma, and anal and liver cancer were found among HIV-positive members. The HIV patients had 200 times the risk for Kaposi's sarcoma, a 40 percent higher risk for liver cancer, and a 55-fold increase for anal cancer. Neither drinking nor smoking appeared to be a factor in any of those cancers other than liver. For reasons not yet understood, the risk of developing prostate cancer was slightly reduced with HIV infection.

Cancer risk increased dramatically in patients whose T-cell counts were below 200. A healthy person typically has a T-cell count of at least 600, and national guidelines call for HIV treatment initiation when the count falls under 500. But the rates of at least five types of cancer were higher even in HIV-positive patients with T-cell counts of 500 or higher. Some doctors and public health experts believe this suggests that early HIV treatment to keep T-cell counts near the level of an uninfected individual could help prevent some cancers.

"Ideally you would want a clinical trial and look at the question of starting people earlier, and if that reduces their burden of cancer," said Silverberg. "The pendulum is swinging toward earlier therapy," he noted. "Not all patients are willing to do earlier treatment, but giving patients all the information available might be very useful."

The study, "HIV Infection, Immunodeficiency, Viral Replication and the Risk of Cancer," was published early online in the journal Cancer Epidemiology Biomarkers & Prevention (2011;doi:10.1158/1055-9965.EPI-11-0777).

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