Cancer Incidence following Expansion of HIV Treatment in Botswana

Background: The expansion of combination antiretroviral treatment (ART) in southern Africa has dramatically reduced mortality due to AIDS-related infections, but the impact of ART on cancer incidence in the region is unknown. We sought to describe trends in cancer incidence in Botswana during implementation of the first public ART program in Africa. Methods: We included 8479 incident cases from the Botswana National Cancer Registry during a period of significant ART expansion in Botswana, 2003–2008, when ART coverage increased from 7.3% to 82.3%. We fit Poisson models of age-adjusted cancer incidence and counts in the total population, and in an inverse probability weighted population with known HIV status, over time and estimated ART coverage. Findings: During this period 61.6% of cancers were diagnosed in HIV-infected individuals and 45.4% of all cancers in men and 36.4% of all cancers in women were attributable to HIV. Age-adjusted cancer incidence decreased in the HIV infected population by 8.3% per year (95% CI -14.1 to -2.1%). However, with a progressively larger and older HIV population the annual number of cancers diagnosed remained constant (0.0% annually, 95% CI -4.3 to +4.6%). In the overall population, incidence of Kaposi’s sarcoma decreased (4.6% annually, 95% CI -6.9 to -2.2), but incidence of non-Hodgkin lymphoma (+11.5% annually, 95% CI +6.3 to +17.0%) and HPV-associated cancers increased (+3.9% annually, 95% CI +1.4 to +6.5%). Age-adjusted cancer incidence among individuals without HIV increased 7.5% per year (95% CI +1.4 to +15.2%). Interpretation Expansion of ART in Botswana was associated with decreased age-specific cancer risk. However, an expanding and aging population contributed to continued high numbers of incident cancers in the HIV population. Increased capacity for early detection and treatment of HIV-associated cancer needs to be a new priority for programs in Africa

HIV prevalence and change in incidence for leading cancers.

<p>Note: IP, inverse probability; 95%CI, 95% confidence interval</p><p>^a Quadratic term was significant for non-Hodgkin’s lymphoma among HIV-infected individuals—4.5% (95%CI -10.1 to 23.9%) per year and -9.45% (95%CI -19.5 to -1.2%) per year².</p><p>HIV prevalence and change in incidence for leading cancers.</p

Annual number of cancer diagnoses among HIV-infected and HIV-uninfected in Botswana.

<p>Analyses used the IPW population.</p

Overall cancer age-adjusted incidence among HIV-infected (solid) and HIV-uninfected (dotted) individuals.

<p>Analyses utilized the IPW population.</p

Trend in standardized incidence ratio (SIR) of cancer comparing HIV infected and HIV uninfected populations during ART expansion.

<p>Analyses utilized the IPW population. Note: ART, combination antiretroviral therapy.</p

Trends in incidence for leading cancers among HIV-infected population.

<p>Estimates from IPW population accounting for changes in overall and age-specific HIV prevalence. Shaded 95% confidence bands from 1000 bootstrap samples. Note: NHL, non-Hodgkin’s lymphoma</p

HIV prevalence and change in incidence for leading cancers.

<p>Note: IP, inverse probability; 95%CI, 95% confidence interval</p><p>^a Quadratic term was significant for non-Hodgkin’s lymphoma among HIV-infected individuals—4.5% (95%CI -10.1 to 23.9%) per year and -9.45% (95%CI -19.5 to -1.2%) per year².</p><p>HIV prevalence and change in incidence for leading cancers.</p

ART treatment coverage and median CD4 at ART initiation during the study period.

<p>Note: ART, combination antiretroviral therapy.</p