Evidence continues to accumulate showing that people with HIV and AIDS may develop cancer earlier and more often despite antiretroviral treatment, but study results are not entirely consistent. (For an overview, see "A Glass Half Full: Cancer Risk for People Living With HIV," in this issue.)
As reported at AIDS 2010 (abstract WEAB0101), Meredith Sheils, Eric Engels and colleagues from the National Cancer Institute (NCI) extended their previous research on changing rates of AIDS-defining and non-AIDS-defining cancers in the ART era.
The investigators looked at rates of cancer among people with HIV and AIDS, with incidence (new cases) determined by linking CDC HIV/AIDS data and cancer registries in 15 areas of the U.S. Rates for people with AIDS were estimated using data from 1991-2005, while those for people with HIV but not AIDS were estimated using data from states with confidential name-based HIV reporting since 2004.
Thanks to widespread adoption of ART in the mid-1990s, the total number of people living with AIDS increased from 93,802 (8% of them age 50 or older) in 1991 to 399,762 (29% age 50 or older) in 2005. During 1991-2005, a total of 76,558 cancer cases were reported in this population.
Cases of AIDS-defining cancer -- primarily Kaposi's sarcoma and non-Hodgkin lymphoma -- declined steeply, from 7,284 in 1993 to 1,736 in 2005. In contrast, non-AIDS cancers increased over time as people with AIDS lived longer, from 416 cases in 1991 to 2,437 in 2005. Anal and prostate cancer rates rose, while incidence of lung cancer and Hodgkin's lymphoma remained relatively stable.
During 2004-2007 in the 34 states with consistent name-based reporting, there were 4,388 cases of cancer among people with HIV (but not necessarily AIDS), including 892 cases of lung cancer, 381 cases of anal cancer and 327 cases of Hodgkin's lymphoma.
"Dramatic increases in non-AIDS-defining cancers among persons with AIDS are driven by growth and aging of the AIDS population, and rising incidence rates for some cancers," the researchers concluded, adding that, "Cancer prevention and treatment in HIV-infected persons are increasingly important."
In a related study published in the August 9, 2010, Archives of Internal Medicine, NCI researchers assessed long-term cancer risk among people with AIDS relative to the general population. Analyzing medical records from more than 263,000 adults and adolescents with AIDS during 1980-2004, they saw an increased risk for all non-AIDS-defining cancers considered together, as well as for several specific malignancies, including Hodgkin's lymphoma, mouth and throat cancers, anal and penile cancer and lung cancer.
An Italian study published in the November 1, 2010, issue of Clinical Infectious Diseases reached a similar conclusion. Antonella Zucchetto and colleagues compared rates of non-AIDS malignancies among 10,392 HIV positive people diagnosed with AIDS during 1999-2006 and members of the general population matched for age and sex.
Over a median follow-up period of 37 months, 7.4% of all deaths among people with AIDS were due to non-AIDS cancers -- more than six times higher than the general population rate. The most common malignancies leading to death in people with AIDS were lung cancer, liver cancer, Hodgkin's lymphoma and head and neck cancers.
Compared with the general population, people with AIDS had elevated mortality rates for several non-AIDS cancers, including anal cancer (270 times higher likelihood of death), Hodgkin's lymphoma (174 times higher), liver cancer (11 times higher) and brain and central nervous system cancers (10 times higher).
People with AIDS had especially elevated risk of death due to cancers with an infectious cause, including anal cancer (caused by human papillomavirus or HPV), Hodgkin's lymphoma (linked to Epstein-Barr virus) and liver cancer (often caused by chronic hepatitis B or C viruses).
Turning to another aspect of cancer risk, the NCI team compared ages at the time of diagnosis of non-AIDS cancers among people with AIDS and the general population. As reported in the October 5, 2010, Annals of Internal Medicine, an analysis of data from more than 212,000 people with AIDS during 1996-2007 showed that the age at diagnosis of most types of cancer was not significantly different for people with and without AIDS after adjusting for age and other factors.
But people with AIDS were significantly younger than the general population, on average, when diagnosed with lung cancer (median 50 vs. 54 years) and anal cancer (42 vs. 45 years) and significantly older when diagnosed with Hodgkin's lymphoma (42 vs. 40 years).
Minh Ly Nguyen from Emory University School of Medicine and colleagues (AIDS 2010 abstract WEAB0105) also looked at age at the time of cancer diagnosis, retrospectively analyzing data from 8,300 people with HIV (but not necessarily AIDS) seen at an urban HIV clinic in Atlanta between 2000 and 2007; only about half were on combination ART.
A total of 512 patients were diagnosed with cancer during this period, a majority (320 cases) being AIDS-defining cancers, especially Kaposi's sarcoma. Incidence rates for most non-AIDS cancers were significantly higher for people with HIV compared with the general population, though this was not the case for prostate or breast cancer. Except for Hodgkin's lymphoma, these cancers were diagnosed 10-15 years earlier, on average, in HIV positive people compared with the general population.
Among the 192 cases of non-AIDS malignancies, 40% were lung cancer (diagnosed at an average age of 52 years in HIV positive people vs. 66 years in the general population), 24% were anal-rectal cancer (age 41 vs. 55), 22% were head and neck cancers (age 51 vs. 61), 18% were prostate cancer (age 53 vs. 64), 16% were Hodgkin's lymphoma (age 40 vs. 42), 11% were breast cancer (age 45 vs. 58) and 10% were liver cancer (age 44 vs. 60).
The researchers concluded, "Many non-AIDS-defining cancers occur at an increased rate compared to the general population and at an earlier age." Again, this was particularly true for malignancies caused by viruses. They therefore recommended that cancer screening for people with HIV "should be considered at an earlier age."
Liz Highleyman (firstname.lastname@example.org) is a freelance medical writer based in San Francisco.