LOS ANGELES - For reasons not yet clear, people with HIV face a higher rate of cancers not usually associated with HIV, a new study suggests.

This increasing rate of "non-AIDS defining cancers" includes lung, head and neck, liver, kidney, and anal cancers, among others, according to the study appearing on the website of the American Association for the Advancement of Science (AAAS) on Monday.

The alarming uptick in cancer rates highlights the critical need to understand how to treat tumors in people taking highly active anti-retroviral therapy (HAART) for HIV, the study noted.

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To explore potential interactions between HAART and the newer cancer drugs, the AIDS Malignancy Consortium (AMC), a National Cancer Institute (NCI)-supported clinical trials group founded in 1995 to support innovative trials for AIDS-related cancers, has conducted the first of a planned series of studies.

John Deeken, M.D., a research physician at Georgetown Lombardi Comprehensive Cancer Center and national chairman of the study, presented the findings during a poster session at the on-going 2011 annual meeting of the American Society of Clinical Oncology ( ASCO) in Chicago, according to the AAAS.

Deeken said these early results already have the potential to change the way that cancer is treated in HIV patients.

"Up to this point, oncologists have not had much information about treating cancer in people taking HAART," said Deeken. "We're basically at square one because people with HIV usually are not included in cancer clinical trials. They're excluded because physicians are worried about causing further immune suppression in HIV patients, and because HAART drugs are notorious for causing drug-drug interactions and serious side effects."

The first drug being studied is sunitinib, which may stop the growth of cancer cells by blocking blood flow to the tumor and by blocking some of the enzymes needed for cell growth. However, agents in the HAART cocktail are thought to affect the same enzymes involved in sunitinib metabolism, according to the report.

The AMC chose to study sunitinib because this oral medication was approved by the Food and Drug Administration to treat kidney cancer, which is occurring at an increasing rate among HIV patients, and the drug is being studied in other cancer types that also affect HIV patients, such as lung and liver cancers, according to Deeken.