People with AIDS Account for Fewer U.S. Cancer Cases

People with AIDS are now contributing proportionately less to total cancer cases in the U.S.

Since the onset of the HIV/AIDS epidemic, various forms of cancer have been a hallmark of the disease. A group of cancers including non-Hodgkin lymphoma (NHL), Kaposi's sarcoma (KS), and cervical cancer are considered AIDS-defining when they occur in people living with HIV. The onset of the epidemic likely contributed to the total numbers of these cancers in the U.S.

Widespread effective antiretroviral therapy (ART) has improved immunological outcomes for people with HIV, leading to lower rates of AIDS-related cancers. However, longer life spans and the overall increase in the number of people living with HIV might lead to a higher incidence and proportion of these cancers in HIV positive people.

In the April 13, 2011, Journal of the American Medical Association, Meredith Shiels and colleagues reported on a study looking at the proportion of people with AIDS among all people diagnosed with AIDS-defining cancer between 1980 and 2007.

Drawing on data from the HIV/AIDS Cancer Match Study and the U.S. Census, the authors looked at what proportion of NHL, KS, and cervical cancer diagnoses occurred among people with AIDS during those years.

Results

The proportion of KS cases among people with AIDS peaked at 90.5% during 1990-1995, dropping to 70.5% during 2000-2007.
Overall incidence of KS dropped from 1117 per 100,000 person years during 1990-1995 to 84.3 per 100,000 person years, a 92% reduction.
The proportion of NHL cases among people with AIDS ranged from 10.2% to 48.3% at their peak during 1990-1995.
The proportion of people living with AIDS among cervical cancer diagnoses was low overall, but increased from 0.11% during 1980-1989 to 0.71% during 2000-2007.

Based on these findings, the author concluded that, "Despite an average prevalence of AIDS in the United States of only 0.07% during 1980-2007, the HIV epidemic has contributed substantially to the total number of certain malignancies."

This effect was strongest with regard to KS, where people with AIDS accounted for 82% of all diagnoses throughout the study, while between 6% and 27% of NHL were among people with AIDS. AIDS contributed to the incidence of cervical cancer by less than 1%. The study also found that proportions of KS and NHL peaked in the period between 1990 and 1995, while the proportion of people with AIDS among cervical cancer cases increased by almost 700%.

In spite of steady increases in the number of people with HIV/AIDS in the U.S., people with AIDS are contributing proportionally less to overall rates of KS and NHL. This is likely explained by improvements in antiretroviral therapy leading to better immunological outcomes among people with HIV. The largest contribution of AIDS to the incidence of KS and NHL happened during 1990-1995, a period of significant growth in the incidence of AIDS in the U.S. and just prior to the advent of highly active antiretroviral therapy (HAART).

The opposite, however, is true for cervical cancer. The authors argue that this is due to increased incidence of AIDS among women during the time period covered by the study. In addition, research has shown that HIV positive women in the U.S. typically undergo regular cervical Pap screening, which allows pre-cancerous cell changes to be detected and treated before they progresses to cancer.

Other studies have found that non-AIDS defining cancers are increasing among people living with HIV. How these might contribute proportionally to general cancer incidence in the population is unknown.

Investigator affiliations: National Cancer Institute, Rockville, MD; Centers for Disease Control and Prevention, Atlanta, GA.

4/26/11

Reference
M Shiels, RM Pfeiffer, I Hall, et al. Proportions of Kaposi Sarcoma, Selected Non-Hodgkin Lymphomas, and Cervical Cancer in the United States Occurring in Persons With AIDS, 1980-2007. Journal of the American Medical Association 305(14):1450-1459 (abstract). April 13, 2011.