Abstract Body

With declining mortality due to infections, cancer has become the leading cause of death among HIV-infected individuals in high-income countries. However, in sub-Saharan Africa where more than two-thirds of HIV infections occur, the relative contribution of infection and malignancy to HIV-associated mortality is unknown. We sought to estimate cancer mortality since availability of antiretroviral treatment (ART) in Botswana, and compare with mortality due to tuberculosis (TB), the leading infectious cause of death in sub-Saharan Africa.

Incidence by cancer type was estimated from 8479 incident cases from the Botswana National Cancer Registry during the period of ART expansion, 2003-2008.  We utilized Poisson regression in an inverse probability weighted population with known HIV status and projected cancer incidence through 2013.  Cancer mortality was estimated using parametric Weibull models from observed survival in a separate prospective cancer cohort in Botswana (2010-2015).  Survival probabilities for each cancer type were assumed to be constant during the study period and all deaths were attributed to cancer.  We utilized estimates from the WHO|Global TB Program (derived from Botswana government data) to estimate TB-HIV deaths.

A total of 808 patients with HIV and cancer followed for median of 12.2 months (IQR 6.1 to 24.3 months) contributed to survival estimates (1.2% loss-to-followup).  Estimated 5-year survival was low: cervix 3.9%, head and neck 4.4%, breast 19.3%, non-Hodgkin lymphoma 39.7%, Kaposi sarcoma 52.1%, and combined other sites 15.1%.  Mortality due Kaposi sarcoma declined over the study period (-4.2% annually, 95% CI -5.0 to -3.3%), but cervical cancer mortality increased (13.3% annually, 95% CI 11.7 to 14.9). Overall cancer mortality increased (1.2% annually, 95% CI 0.7 to 3.1%) while TB mortality declined substantially between 2003 and 2013.  In 2013, projected cancer mortality (293 per 100,000, 95%CI 264-331) approximated projected TB mortality (324 per 100,000, estimate range 241-419).

With ART coverage exceeding 90%, mortality due to cancer in HIV-infected individuals has increased in Botswana and now likely exceeds mortality due to TB.  Cervical cancer mortality is rising sharply.  Interventions to reduce cancer risk, establish screening programs, and improve access to treatment are urgently needed for HIV-infected individuals.