As treatments for HIV/AIDS improve and patients are living longer, the distribution of cancers in this population has undergone a dramatic shift in the United States. While cases of the types of cancer that have been associated with AIDS progression have decreased, cases of other types of cancer are on the rise. These results, reported by scientists from the National Cancer Institute (NCI), part of the National Institutes of Health, and the Centers for Disease Control and Prevention, were published online April 11, 2011, in the Journal of the National Cancer Institute.
The CDC uses the presence of certain diseases, including three cancers – Kaposi sarcoma, non-Hodgkin lymphoma, and invasive cervical cancer – as part of the criteria to determine whether an HIV-infected person has developed AIDS. The introduction of highly active antiretroviral therapy (HAART) in 1996 resulted in improved immune function, reduced risk of AIDS progression, and greatly improved survival for people infected with HIV. As a result, cases of those AIDS-defining cancers decreased threefold, from 34,000 cases between 1991 and 1995 to about 10,000 cases between 2001 and 2005. In contrast, the total number of all other cancers tripled, from around 3,000 in the earlier period to 10,000 in the latter period. Since 2003, annual counts of these other cancers in the HIV/AIDS population have exceeded the number of AIDS-defining malignancies.
"Our study observed striking increases for a number of malignancies related to cancer risk factors that are known to be prevalent in this population, such as smoking and infection with cancer-causing viruses," said study author Meredith S. Shiels, Ph.D., from NCI's Division of Cancer Epidemiology and Genetics (DCEG). "We also observed increases for nearly all other cancers, which is what one might expect for an aging population."
People with HIV infection are known to be at increased risk for certain cancers not classified as AIDS-defining malignancies. Of these, the most common are anal, lung, and liver cancers, and Hodgkin lymphoma. Higher risks for these four malignancies stems from co-infections such as human papillomavirus (HPV), hepatitis B and C viruses, and Epstein-Barr virus, as well as higher smoking rates in the HIV/AIDS population. These four non-AIDS-defining malignancies made up nearly half of all cancers diagnosed in this population from 2001 through 2005. These cancers increased dramatically over the 15 years; there were eight times more anal cancer, double the number of lung cancers and Hodgkin lymphomas, and five times as many liver cancers in 2001 through 2005 as compared to 1991 through 1995.
"The changing number and types of cancer for people with HIV/AIDS highlights the need for research focusing on the specific cancer prevention needs of this population, including smoking cessation, treatment of hepatitis B and C viral infections, and prevention and screening for HPV-related cancers," said senior investigator Eric A. Engels, M.D., also from DCEG.
The increase in non-AIDS defining malignancies from 1991 through 2005 reflects a quadrupling of the number of people in the United States living with AIDS, and a substantial age shift in this population due to an increase in people age 40 and over. Since cancer typically occurs at older ages, an increase in incidence would be expected as the HIV/AIDS population grows older.
"These findings highlight the need for more research toward understanding how the combination of prolonged HIV infection, aging, and other factors may contribute to cancer development," added study author Robert Yarchoan, M.D., director of NCI's Office of HIV and AIDS Malignancy.
The researchers estimated the number of AIDS-defining and other cancers in people with AIDS by using cancer incidence rates from the NCI's HIV/AIDS Cancer Match Study, and estimated counts for the U.S. HIV population from CDC surveillance data. The researchers were limited in their ability to estimate cancer rates for the subset of people who were infected with HIV but did not have AIDS because a substantial proportion of HIV cases in this country are undiagnosed, and data for people infected with HIV who have not developed AIDS were not available from all states for this analysis.
Source: NIH/National Cancer Institute