Mortality due to cancer among people with AIDS: a novel approach using registry-linkage data and population attributable risk methods.

Abstract

Deaths related to HIV/AIDS have declined due to improved HIV therapies. However, people with AIDS remain at elevated risk for cancer and cancer deaths. Prior studies evaluated cancer deaths using death certificates, which may be inaccurate. We utilized population attributable risk methods (which do not rely on death certificates) to assess cancer mortality. Data from a US population-based record linkage study were used to identify incident cancers and deaths in 372 364 people with AIDS (1980-2006) followed for up to 5 years after AIDS onset. We utilized Cox regression to compare mortality in individuals with and without cancer and to calculate cancer-attributable mortality across calendar periods (AIDS onset in 1980-1989, 1990-1995, and 1996-2006). Mortality declined across calendar periods for all people with AIDS but remained higher among those with cancer relative to those without. During 1996-2006, among individuals with an AIDS-defining cancer (ADC) who died, 88.3% of deaths were attributable to their ADC; likewise, among individuals with a non-AIDS-defining cancer (NADC), 87.1% of deaths were attributable to their NADC. The fraction of all deaths in people with AIDS attributable to ADC (i.e. population-attributable risk) decreased significantly from 6.3% (1980-1990) to 3.9% (1996-2006), but NADC population attributable mortality increased significantly over time from 0.5% (1980-1989) to 2.3% (1996-2006). Among individuals with AIDS and cancer who subsequently die, most deaths are attributable to cancer. With a decline in overall mortality, the proportion of all deaths attributable to NADCs has increased. These results highlight the need for improved cancer prevention and treatment.