By Will Dunham

WASHINGTON, May 20 (Reuters) - People with HIV have a much higher risk for many cancers, including anal cancer, but a lower risk for prostate cancer, researchers said on Tuesday.

Some types of cancers like Kaposi's sarcoma and non-Hodgkin lymphoma have long been associated with people infected by the AIDS virus.

The study focused on trends from 1992 to 2003, finding that these two types of cancer became relatively less common among HIV-infected people in the United States. But other cancers are on the rise among these patients, who are living longer thanks to anti-HIV drugs.

Anal cancer by 2003 had become 59 times more common among HIV-infected people than the general population, according to the study in the Annals of Internal Medicine.

Hodgkin's disease was 18 times more common in this population, the study also found. In addition, liver cancer was seven times more common, lung cancer 3.6 times more common, the skin cancer melanoma and throat cancer both three times more common, and colorectal cancer 2.4 times more common.

The study involved 54,780 men and women infected with the human immunodeficiency virus, which causes AIDS.

It found HIV-infected people had a small reduced risk for prostate cancer. The researchers said that may be because men with HIV infections are more likely to have lower testosterone levels, which could be protective against prostate cancer.

"The study was done because we all know that now people with HIV are living longer, and HIV is looking more like a chronic disease. So we wanted to look at one of the other very large chronic killers in America, cancer," Dr. Pragna Patel of the U.S. Centers for Disease Control and Prevention, who led the study, told Reuters.

SCREENING IMPORTANT

Patel said doctors who care for HIV-infected people should be aware of this increased risk for a range of cancer types, and consider screening.

She called the study the largest analysis of cancer trends among HIV-infected people in the United States ever done.

The virus devastates the body's immune system, raising susceptibility to illnesses and infections. Many early AIDS patients developed Kaposi's sarcoma, a cancer previously associated with older people or people receiving immunosuppressant medications following an organ transplant.

But the advent of combination drug therapy in the 1990s called highly active antiretroviral therapy, or HAART, greatly extended the lives of many HIV-infected people, particularly in developed countries.

"Most significant was the finding of anal cancer being so elevated even in the HAART era," Patel said.

She said multiple factors may be involved, but the increased risk may be linked to the fact that anal sex by homosexual men can spread the human papillomavirus, or HPV, which is known to cause anal cancer.

"Of course, anal sex and how many times you have anal sex and how many sex partners you have -- that all matters with regard to HPV infection," Patel said.

Human papillomaviruses are common viruses that can cause warts among other things. About 30 types increase the risk for cancers, including cervical cancer. These are passed through sexual contact with an infected partner. (Editing by Maggie Fox)

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