A prospective ascertainment of cancer incidence in sub‐Saharan Africa: The case of Kaposi sarcoma

Aggrey Semeere,Winnie Muyindike,Jeffrey Martin,Barbara Castelnuovo,Mwebesa Bwana,Beverly Musick,David Glidden,Naftali Busakhala,Megan Wenger,Philip Leboit,Nathan Buziba,Andrew Kambugu,Constantin Yiannoutsos,Timothy Mccalmont,Erin Amerson,Miriam Laker‐Oketta,Kara Wools‐Kaloustian,Robert Lukande,Toby Maurer

doi:10.1002/cam4.618

Abstract

In resource‐limited areas, such as sub‐Saharan Africa, problems in accurate cancer case ascertainment and enumeration of the at‐risk population make it difficult to estimate cancer incidence. We took advantage of a large well‐enumerated healthcare system to estimate the incidence of Kaposi sarcoma (KS), a cancer which has become prominent in the HIV era and whose incidence may be changing with the rollout of antiretroviral therapy (ART). To achieve this, we evaluated HIV‐infected adults receiving care between 2007 and 2012 at any of three medical centers in Kenya and Uganda that participate in the East Africa International Epidemiologic Databases to Evaluate AIDS (IeDEA) Consortium. Through IeDEA, clinicians received training in KS recognition and biopsy equipment. We found that the overall prevalence of KS among 102,945 HIV‐infected adults upon clinic enrollment was 1.4%; it declined over time at the largest site. Among 140,552 patients followed for 319,632 person‐years, the age‐standardized incidence rate was 334/100,000 person‐years (95% CI: 314–354/100,000 person‐years). Incidence decreased over time and was lower in women, persons on ART, and those with higher CD4 counts. The incidence rate among patients on ART with a CD4 count >350 cells/mm3 was 32/100,000 person‐years (95% CI: 14–70/100,000 person‐years). Despite reductions over time coincident with the expansion of ART, KS incidence among HIV‐infected adults in East Africa equals or exceeds the most common cancers in resource‐replete settings. In resource‐limited settings, strategic efforts to improve cancer diagnosis in combination with already well‐enumerated at‐risk denominators can make healthcare systems attractive platforms for estimating cancer incidence.

Highlights

Kaposi sarcoma (KS) is an example of a malignancy in a resource-limited setting which would benefit from knowledge about incidence
Differences between settings regarding the strain of the etiologic viral agent (Kaposi sarcoma-associated herpesvirus, KSHV), ambient human immunodeficiency virus (HIV) strains, human host, and potentially other environmental cofactors dictate that KS incidence must be directly measured in Africa for it to be relevant
In the analysis of prevalent KS upon medical center enrollment, we evaluated 102,945 HIV-infected adults (See Figure 1), 10,519 (10%) from the Immune Suppression Syndrome (ISS)–Uganda, 7332 (7%) from the Infectious Diseases Institute (IDI)–Uganda, and 85,094 (83%) from the Academic Model Providing Access to Healthcare (AMPATH)–Kenya

Summary

Methods

We performed a cohort analysis among HIV-infected adults (≥18 years old) receiving care at one of three medical centers in Kenya and Uganda that participate in the East Africa IeDEA Consortium. The average number of patients cared for per year during the study period was 55,502 at AMPATH, 10,428 at IDI, and 8329 at the ISS Clinic. Each of these systems provides the standard-o f-care management of HIV disease, including counseling, free cotrimoxazole prophylaxis, and free ART. All analyses were performed with Stata (version 13.1, Stata Corp., College Station, TX, USA)

Results

Discussion

Method of KS diagnosis