New Analysis Confirms Higher Risk of Non-AIDS-defining Cancers in HIV Positive People

By Liz Highleyman

A recent meta-analysis adds to the evidence that HIV infection is associated with a higher risk of non-AIDS-related cancer as well as classic AIDS-defining malignancies.

As recently reported, investigators studying the European D:A:D cohort found that HIV positive individuals were more likely than the general population to develop non-AIDS cancers, and that the risk rose as CD4 cell count declined.

Traditionally, only Kaposi's sarcoma, non-Hodgkin lymphoma, and cervical cancer have been classified as AIDS-defining. However, anal cancer is caused by the same strains of human papillomavirus (HPV) as cervical cancer, and several other malignancies have a known -- for example, liver cancer due to hepatitis B or C virus -- or suspected link to infectious agents.

At the 7th Annual American Association for Cancer Research International Conference on Frontiers in Cancer Prevention Research this week, Meredith Shiels of Johns Hopkins School of Public Health and colleagues presented findings from a meta-analysis of cancer rates in people with HIV and AIDS.

The analysis included 11 international studies (mostly from Europe) comparing cancer rates in HIV positive individuals and those in the general population, as determined from cancer registries. A total of 2100 cancer cases were included.

The investigators found that people with HIV overall had about twice the risk of cancer as uninfected individuals. Among HIV positive men, the standardized incidence ratio was 2.3 (or more than 2 times higher than HIV negative men), while among HIV positive women it was 1.5 (or 50% higher than HIV negative women).

Cervical Cancer

Cancers that occurred at a higher rate in the HIV positive group included head, neck, lung, and liver cancer. Like cervical and anal cancer, some head and neck cancers have been linked to HPV. Some experts have suggested that unidentified infectious agent may contribute to lung cancer, which is more common among HIV positive people independent of smoking status.

Somewhat surprisingly, cancer rates in this analysis were similar in people diagnosed with AIDS (presence of specific AIDS-defining illnesses or a CD4 count < 200 cells/mm3) and in those with earlier disease and better preserved immune function (incidence ratios of 1.88 and 1.98, respectively).

But this adds to a growing body of evidence that HIV causes detrimental effects throughout the body -- perhaps related to inflammation or immune dysregulation -- well before CD4 cells fall to a dangerously low level. It is also possible that certain antiretroviral agents may be carcinogenic with long-term use.

The researchers recommended that patients and clinicians should pay more attention to well-known modifiable cancer risk factors -- such as cigarette smoking, which Shiels noted is known to be higher among HIV-infected individuals.

11/12/08

Reference
Shiels M, and others. A meta-analysis of the incidence of non-AIDS cancers in HIV-infected individuals. 7th Annual AACR International Conference on Frontiers in Cancer Prevention Research. National Harbor, MD. November 16-19, 2008. Abstract A117.

Other sources
American Association for Cancer Research. Individuals with HIV Have Higher Risk of Non-AIDS Cancers. Press release. November 18, 2008.