How HIV Increases Your Risk of Cancer

The incidences of cancer in people living with HIV have long been an area of concern and the focus of increasing research by medical investigators. While the risk for such AIDS-defining cancers as Kaposi sarcoma and non-Hodgkin lymphoma (NHL) have dropped sharply due to the advances in antiretroviral therapy, the incidences of other cancers have risen just as steeply.

These non-AIDS-defining cancers are today considered the leading cause of death for HIV-infected people in the developed world, according to research from the Swiss HIV Cohort Study. Incidences of malignancies like lung cancer and anal cancer are now running anywhere from three to 50 times greater than that of the general population.

AIDS-Defining Cancers

At the beginning of the 1980s, a rare form of skin cancer called Kaposi sarcoma (which, until then, had primarily affected elderly men in Eastern Europe) was among a group of infections seen in people diagnosed with HIV. Soon after, non-Hodgkin lymphoma and invasive cervical carcinoma (ICC) were added to the list as cancers deemed AIDS-defining.

With the introduction of combination antiretroviral therapy (ART) in 1996, the landscape changed dramatically. Armed with a regimen of drugs that could now fully suppress the virus and restore the body's immune function, the incidences of Kaposi and NHL dropped by nearly 50%, while ICC has remained more-or-less unchanged to this day. 

(The reason for this is not fully understood although some believe that certain, less treatable strains of human papillomavirus (HPV)—known to cause cervical cancer—may predominate in women with HIV.)

Despite many of these advances, people with HIV are still up to seven times more likely to develop ICC, 65 times more likely to develop NHL, and 300 times more likely than to develop Kaposi sarcoma than their non-infected counterparts.

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Non-AIDS-Defining Cancers

With vast increases in life expectancy due to ART and the gradual aging of the HIV population, researchers began to see other types of cancers appearing more frequently in people with HIV. The frequency by which these occurred led many to believe that there was a causal link between HIV and certain types of cancer.

For some of these, like anal cancer, the link seemed clear. Once largely unseen in the U.S., with little more than 20,000 cases reported between 1980 and 2005, anal cancer today is the fourth most common cancer found in HIV-infected people. Moreover, gay or bisexual men with HIV may have as much as 60 times greater chance of developing anal cancer than non-infected individuals.

Similarly, Hodgkin's disease (a type of blood cancer similar to non-Hodgkin lymphoma) is between five to 10 times more likely to affect people with HIV, while head/neck cancer and liver cancer are, respectively, eight and nine times more likely to occur.

All told, cancers of the brain, mouth, throat, lungs, liver, kidneys, cervix, anus and lymph tissue are seen to disproportionately affect people with HIV, with most being diagnosed 10-15 years earlier than their non-infected counterparts.

(On the flip side, people with HIV are generally not seen to be at any higher risk for the development of cancers of the breast, ovaries, bladder, prostate, colon, or rectum.)

Causes for the Increased Risk

Certain co-infections have been shown to contribute to the increased risk, such as that between hepatitis C and liver cancer; HPV and anal/cervical cancer; and the Epstein Barr virus and Hodgkin's disease.

Meanwhile, traditional lifestyle factors, like smoking and alcohol, can further complicate risk, particularly with lung or liver cancers.

More importantly, perhaps, is the role of HIV itself. While we know that HIV doesn't specifically cause cancer, the persistent inflammation associated with infection appears to be strongly linked to the high incidence rate. This appears true even when patients are on ART with fully undetectable viral loads.

Research today strongly suggests that persistent inflammation, even at low levels, can prematurely age the immune system. This deterioration (known as premature senescence) is considered natural in older people. However, with HIV-associated inflammation, this premature aging not only speeds up the time to takes to develop cancer, but it does so with many other aging-related conditions, from neurocognitive impairment to bone deterioration to cardiovascular disease.

How to Reduce Your Cancer Risk

Key to the reduction of cancer risk is the early diagnosis and treatment of HIV infection. The initiation of ART at the time of diagnosis can maintain or restore healthy immune function while reducing the risk of some cancers by as much as 50%.

Other recommendations for HIV-positive persons include:

• Annual pap smear screening for cervical cancer
• Hepatitis B and hepatitis C testing
• Periodic anal pap smear tests for gay/bisexual men or any person with anal warts
• HPV vaccination for females ages 11 to 26, males ages 11 to 21, sexually active men who have sex with men (MSM) ages 22 to 26, or immunosuppressed men ages 22 to 26
• Smoking cessation
• Reducing alcohol consumption, particularly for persons with hepatitis B or C
• Safer sex practices to prevent hepatitis C and HPV infection
• Other cancer-specific screening tests as directed by your physician