HIV treatment as good at preventing AIDS-related cancers as at preventing opportunistic infections

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Antiretroviral therapy is as effective in protecting against AIDS-defining cancers as it is at preventing other AIDS-defining illnesses, say US researchers, in an article published in the Journal of Acquired Immune Deficiency Syndromes.

Although research on the effectiveness of antiretroviral therapy has tended to concentrate on its impact on survival, it has been shown to reduce the incidence of specific AIDS-defining events. These are made up of AIDS-defining cancers (like Kaposi’s sarcoma and non-Hodgkin’s lymphoma), opportunistic infections (like pneumonia) and other events (like HIV-related dementia).

But what has not been clear is whether antiretroviral therapy is as good at preventing AIDS-defining cancers as it is other AIDS-defining illnesses. Therefore researchers looked at information on use of anti-HIV drugs and AIDS-defining illnesses in 2121 HIV-positive men over the period from 1990 to 2006.

Glossary

AIDS defining condition

Any HIV-related illness included in the list of diagnostic criteria for AIDS, which in the presence of HIV infection result in an AIDS diagnosis. They include opportunistic infections and cancers that are life-threatening in a person with HIV.

Kaposi's sarcoma (KS)

Lesions on the skin and/or internal organs caused by abnormal growth of blood vessels.  In people living with HIV, Kaposi’s sarcoma is an AIDS-defining cancer.

seroconversion

The transition period from infection with HIV to the detectable presence of HIV antibodies in the blood. When seroconversion occurs (usually within a few weeks of infection), the result of an HIV antibody test changes from HIV negative to HIV positive. Seroconversion may be accompanied with flu-like symptoms.

 

opportunistic infection (OI)

An infection that occurs more frequently or is more severe in people with weakened immune systems, such as people with low CD4 counts, than in people with healthy immune systems. Opportunistic infections common in people with advanced HIV disease include Pneumocystis jiroveci pneumonia; Kaposi sarcoma; cryptosporidiosis; histoplasmosis; other parasitic, viral, and fungal infections; and some types of cancer. 

lymphoma

A type of cancer that starts in the tissues of the lymphatic system, including the lymph nodes, spleen, and bone marrow. In people who have HIV, certain lymphomas, such as Burkitt lymphoma, are AIDS-defining conditions.

They used data from two large US HIV cohorts - the Tri-Service AIDS Clinical Consortium (TACC) and the Multicenter AIDS Cohort Study (MACS). During that time there were 81 AIDS-defining cancers – 64 cases of Kaposi’s sarcomas and 17 non-Hodgkin's lymphomas – and 343 other AIDS events.

By comparing disease rates before and after the introduction of effective HIV treatment they found that the reduction in AIDS-defining cancers was practically the same (74%) as the reduction in other AIDS-defining illnesses (72%). The similarity of the effect was maintained after adjusting for age, infection duration and race the researchers add.

They stress that a strength of their analysis is that they used patients who formed part of two of the largest, well-characterised cohorts of HIV-positive people in the US – TACC and MACS. Because there was a known date of HIV seroconversion it allowed the researchers to carefully control for duration of HIV infection. This was important as length of infection has an obviously powerful effect on progression to AIDS.

They conclude that their research provides reassurance that antiretroviral therapies targeted at enhancing the immune system and preventing AIDS diagnoses in general are equally protective against various types of AIDS-defining events among HIV-positive men.

References

Shiels MS et al. Effect of HAART in incident cancer and noncancer AIDS events among male HIV seroconverters. Journal of Acquired Immune Deficiency Syndromes 48, 485-490, 2008.