The finding comes from a study comparing 1996-2008 medical records of nearly 21,000 people with HIV to those of over 215,000 matched people without HIV. That was enough data to calculate risk for 10 kinds of cancer.
"The incidence rates of six of 10 cancers were markedly elevated in HIV patients," study leader Michael Silverberg, PhD, MPH, of Kaiser Permanente's research division, says in a news release.
People with HIV had:
- 199-fold higher risk of Kaposi's sarcoma (KS), one of the diseases first connected to AIDS. It's an AIDS-defining condition, meaning that KS indicates an AIDS diagnosis in a person with HIV.
- 15-fold higher risk of non-Hodgkin lymphoma (NHL). NHL is also an AIDS-defining condition.
- 55-fold higher risk of anal cancer.
- 19-fold higher risk of Hodgkin lymphoma.
- 1.8-fold higher risk of melanoma.
- 1.8-fold higher risk of liver cancer.
A low CD4 T-cell count is an indicator of reduced immunity in people with HIV. It was no surprise that as CD4 counts went down, risk of KS and NHL went up. But as CD4 counts declined, risk of other cancers wet up, too: anal cancer, Hodgkin lymphoma, and colorectal cancer.
People with HIV and a CD4 count of under 500 cells/microliter were at increased risk of melanoma and liver cancer. Those with a CD4 count under 200 were also at increased risk of lung cancer and cancer of the mouth and throat.
"For most cancers studied -- eight of 10 -- HIV patients with the lowest CD4 had higher rates," Silverberg says. "These findings need confirmation in other studies, particularly colorectal cancer, which has not previously been linked to immunodeficiency."
But the AIDS virus itself is not entirely responsible for increased cancer risk in people with HIV. This population also had higher rates of cancer risk factors such as smoking and alcohol use.
"We believe our results support cancer prevention strategies that combine routine prevention activities, such as smoking cessation, with earlier HIV treatment to help maintain a patient's immune system," Silverberg said.
The Silverberg study is not the first to show increased cancer risk in people with HIV. But it's the first to compare people with and without HIV while taking non-HIV risk factors into account.
The findings appear in the Nov. 22 online edition of Cancer Epidemiology, Biomarkers and Prevention.