Premature Aging Not a Concern Yet
Previous studies have found that people with HIV infection are diagnosed with lung, liver, and colon cancer as early as 20 years before the general population. But does this mean that HIV-positive patients are vulnerable to a syndrome of premature aging, thus increasing their cancer risk? Meredith S. Shiels, PhD, MHS, and colleagues also mined data from the US HIV/AIDS Cancer Match Study to compare the ages at diagnosis for 26 non–AIDS-defining cancers in both AIDS patients and the general population, after adjusting for age and other demographic characteristics. Dr. Pfeiffer and Dr. Engels served as co-authors on this study (Ann Intern Med. 2010;153:452-60).
The analysis included 212,055 people with AIDS who were followed for cancer during the HAART era. The median age at diagnosis was 38 years. The most common types of cancer were lung (24%), followed by anal cancer (11%) and Hodgkin’s lymphoma (9%).
Because HIV is generally acquired at a younger age, and because these patients have a shorter life expectancy, the proportion of AIDS patients who are older is far smaller than in the general population. For most types of cancer, the median observed age at diagnosis was about two decades younger among AIDS patients than in the general population, the authors reported.
But after adjusting for underlying population structures to remove any bias, they found a negligible difference between the ages of the two groups at cancer diagnosis. For example, for colon cancer, the median observed age at diagnosis in the AIDS population, and the median expected age at diagnosis, were identical at 52 years (P = .53). The authors also found no difference in the median ages at diagnosis in AIDS patients and in the general population for colon, prostate, or breast cancer (P > .001).
However, AIDS patients were diagnosed at a younger age compared with the general population for lung cancer (50 years vs 54 years) and anal cancer (42 vs 45 years; P < .001). The age at diagnosis for Hodgkin lymphoma was greater in the AIDS population (42 years vs 40 years; P < .001). The authors offered some possible explanations: (1) the effect of HIV on the development of these cancers, and (2) increased medical surveillance of AIDS patients, which results in a lead-time bias.
“Our results do not support including cancer as part of a general syndrome of premature aging in HIV-infected persons,” the authors wrote. AIDS patients may have been diagnosed with cancer at a younger age because there were very few older AIDS patients at the time of the cancer match study. As the AIDS population lives longer and continues to age, differences in age at cancer diagnosis will attenuate. Overall, their results do not support an accelerated cancer screening schedule in HIV-positive patients, although more aggressive screening for cervical or anal cancer may be advisable, they said.
JEFFREY MARTIN, MD, MPH
PAUL VOLBERDING, MD
The hypothesis of premature aging in HIV infection—that comorbid conditions seem to be more common in these patients and occur at a younger age than in the general population—is an intriguing one, but it remains a hypothesis, wrote Dr. Martin and Dr. Volberding. The study results of Dr. Shiels and colleagues “do not support premature aging as a cause of cancer among HIV-infected persons. The article … is an important stepping stone in our path to clarifying a relationship of HIV with premature aging,” they said (Ann Intern Med 2010;153:477-8).
In order to establish accelerated aging as a true complication of HIV infection, there needs to be a better understand of the normal biological aging process, they explained. In addition, research in this area must come to a consensus about definitions for HIV-related aging and offer valid epidemiologic studies to show examples of premature aging.