Cancer burden in the HIV-infected population in the United States

Abstract

Background: Effective antiretroviral therapy has reduced the risk of AIDS and dramatically prolonged the survival of HIV-infected people in the United States. Consequently, an increasing number of HIV-infected people are at risk of non-AIDS-defining cancers that typically occur at older ages. We estimated the annual number of cancers in the HIV-infected population, both with and without AIDS, in the United States.

Methods: Incidence rates for individual cancer types were obtained from the HIV/AIDS Cancer Match Study by linking 15 HIV and cancer registries in the United States. Estimated counts of the US HIV-infected and AIDS populations were obtained from Centers for Disease Control and Prevention surveillance data. We obtained estimated counts of AIDS-defining (ie, Kaposi sarcoma, non-Hodgkin lymphoma, and cervical cancer) and non-AIDS-defining cancers in the US AIDS population during 1991-2005 by multiplying cancer incidence rates and AIDS population counts, stratified by year, age, sex, race and ethnicity, transmission category, and AIDS-relative time. We tested trends in counts and standardized incidence rates using linear regression models. We multiplied overall cancer rates and HIV-only (HIV infected, without AIDS) population counts, available from 34 US states during 2004-2007, to estimate cancers in the HIV-only population. All statistical tests were two-sided.

Results: The US AIDS population expanded fourfold from 1991 to 2005 (96,179 to 413,080) largely because of an increase in the number of people aged 40 years or older. During 1991-2005, an estimated 79 656 cancers occurred in the AIDS population. From 1991-1995 to 2001-2005, the estimated number of AIDS-defining cancers decreased by greater than threefold (34,587 to 10,325 cancers; P(trend) < .001), whereas non-AIDS-defining cancers increased by approximately threefold (3193 to 10,059 cancers; P(trend) < .001). From 1991-1995 to 2001-2005, estimated counts increased for anal (206 to 1564 cancers), liver (116 to 583 cancers), prostate (87 to 759 cancers), and lung cancers (875 to 1882 cancers), and Hodgkin lymphoma (426 to 897 cancers). In the HIV-only population in 34 US states, an estimated 2191 non-AIDS-defining cancers occurred during 2004-2007, including 454 lung, 166 breast, and 154 anal cancers.

Conclusions: Over a 15-year period (1991-2005), increases in non-AIDS-defining cancers were mainly driven by growth and aging of the AIDS population. This growing burden requires targeted cancer prevention and treatment strategies.

Figure 1

Number of people living with AIDS, AIDS-defining cancers, non-AIDS-defining cancers, and all cancers in the United States during 1991–2005. A) US AIDS population by calendar year and age group. B) The estimated counts and standardized rates of AIDS-defining cancers among people living with AIDS in the United States by calendar year and age group. C) The estimated counts and standardized rates of non-AIDS-defining cancers among people living with AIDS in the United States by calendar year and age group. Of note, the bars for 0–12 year olds in panels (B) and (C) are difficult to see because of small numbers of cancers in this age group during 1991–2005 (122 AIDS-defining cancers and 25 non-AIDS-defining cancers). D) The estimated counts and standardized incidence rates of total cancers among people living with AIDS in the United States, stratified by AIDS-defining cancers, non-AIDS-defining cancers, and poorly specified cancers. Bars depict the estimated number of cancers, and points connected by lines depict incidence rates standardized to the 2000 US AIDS population by age group, race, and sex.

Figure 2

Cancer burden of Kaposi sarcoma, non-Hodgkin lymphoma, and cervical cancer among people living with AIDS in the United States during 1991–2005. A) Estimated counts (ie, number of cancers) and standardized incidence rates of Kaposi sarcoma. B) Estimated counts and standardized incidence rates of non-Hodgkin lymphoma. C) Estimated counts and standardized incidence rates of cervical cancer among women. Bars depict the estimated counts and points connected by lines depict the incidence rates standardized to the 2000 US AIDS population by age group, race, and sex. Trends in cancer counts and rates were estimated with linear regression. Two-sided P values were calculated using the χ² test.

Figure 3

Cancer burden of selected non-AIDS-defining cancers among people living with AIDS in the United States during 1991–2005. A) Estimated counts (ie, number of cancers) and standardized incidence rates of anal cancer. B) Estimated counts and standardized incidence rates of lung cancer. C) Estimated counts and standardized incidence rates of liver cancer. D) Estimated counts and standardized incidence rates of Hodgkin lymphoma. E) Estimated counts and standardized incidence rates of prostate cancer among men. F) Estimated counts and standardized incidence rates of colorectal cancer. Bars depict the estimated counts and points connected by lines depict incidence rates standardized to the 2000 US AIDS population by age group, race, and sex. The horizontal dashed lines represent a reference line corresponding to 100 cancers. Trends in cancer counts and rates were estimated with linear regression. Two-sided P values were calculated using the χ² test.