HIV increases cancer risk

8 Oct 2009

CD4 cell count key predictive risk factor for both AIDS-defining and non-AIDS-defining cancers in patients with HIV

Immunodeficiency (falling CD4 cell count) increases the risk of at least seven cancers in people with HIV. As such, earlier diagnosis of HIV and earlier initiation of treatment with antiretroviral therapy could delay the onset of some cancers in HIV patients, finds research published in an article in the November issue of The Lancet Oncology.

Improvements in treatment are enabling people with HIV/AIDS to live much longer lives, and it is well known that this longer life expectancy increases the likelihood of cancer. Less well understood are the links between antiretroviral therapy and the effect of HIV infection itself on the risk of certain cancers.

To address this issue, a team of researchers from France examined the incidence of three AIDS-defining cancers (Kaposi’s sarcoma, non-Hodgkin lymphoma, and cervical cancer) and four non-AIDS-defining cancers (Hodgkin’s lymphoma, lung cancer, liver cancer, and anal cancer) in 52,278 HIV-infected patients during 1998–2006. They also investigated the relationship between immunodeficiency, viral load, antiretroviral treatment, and the onset of these cancers.

Using data from the French Hospital Database on HIV (ANRS C04), they tested 78 models for each cancer with different classifications of immunodeficiency (defined by current CD4 cell count), viral load (defined by HIV RNA value), and combination antiretroviral therapy (cART).

Overall, immunodeficiency increased the risk of all the cancers. As such, CD4 count was the most predictive risk factor for all cancers except anal cancer. The level of risk associated with viral load was shown to be consistently lower than that associated with immunodeficiency.

Findings showed that CD4 count was the only risk factor for Hodgkin’s lymphoma, lung cancer, and liver cancer. But lower CD4 count, higher HIV viral load, and a lack of cART treatment increased the risk of Kaposi’s sarcoma and non-Hodgkin lymphoma.

Additionally, a higher CD4 cell count was linked with a lower risk of cervical cancer, but patients taking cART were half as likely to develop this cancer. The risk of anal cancer increased with the time during which CD4 count was less than 200 cells per µl, and viral load was greater than 100,000 copies per ml.

“Our results suggest that cART would be most beneficial if it restores or maintains the CD4 count above 500 cells per µl, thereby indicating an earlier diagnosis of HIV infection and earlier treatment initiation”, say the authors.

They conclude by calling for effective cancer-specific screening programmes, such as for lung and anal cancer, to be assessed in patients with HIV, and for all HIV-positive women to be regularly offered cervical cancer screening.