Breast cancer survival in sub-Saharan Africa by age, stageat diagnosis and human development index: a population-basedregistry study

Abstract

Breast cancer is the leading cancer diagnosis and second most common cause of cancer deaths in sub-Saharan Africa (SSA).Yet, there are few population-level survival data from Africa and none on the survival differences by stage at diagnosis. Here,we estimate breast cancer survival within SSA by area, stage and country-level human development index (HDI). We obtaineddata on a random sample of2,588breast cancer incident cases, diagnosed in2008–2015from14population-based cancerregistries in12countries (Benin, Cote d’Ivoire, Ethiopia, Kenya, Mali, Mauritius, Mozambique, Namibia, Seychelles,Key words:breast cancer, stage, human development index, survival, AfricaAbbreviations:AFCRN: African Cancer Registry Network; AJCC: American Joint Committee on Cancer; ASRS: age-standardized relative sur-vival; CI: confidence interval; DCO: death certificate only; GNI: Gross National Income; HDI: human development index; IARC: InternationalAgency for Research on Cancer; ICD-10: International Classification of Disease 10th revision; ICSS: International Cancer Survival Standard;KM: Kaplan–Meier; LFU: loss to follow-up; LMIC: low- and middle-income countries; MIR: mortality to incidence ratio; MV: microscopicallyverified; PBCR: population-based cancer registry; RS: relative survival; SSA: sub-Saharan Africa; TNM: tumor node metastasis; WHO: WorldHealth OrganizationAdditional Supporting Information may be found in the online version of this article.Grant sponsor:Centre International de Recherche sur le Cancer;Grant sponsor:Martin-Luther-Universität Halle-Wittenberg;Grant sponsor:UK Government;Grant sponsor:Cancer Research UK;Grant number:C8225/A21133DOI:10.1002/ijc.32406This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproductionin any medium, provided the original work is properly cited.History:Received 26 Oct 2018; Accepted 14 Feb 2019; Online 14 May 2019Correspondence to:Walburga Yvonne Joko-Fru, Nuffield Department of Population Health, University of Oxford, Richard Doll Building,Roosevelt Drive, Oxford OX3 7LF, United Kingdom, Tel.: +447393830970, E-mail: yvonne.jokowalburga@dph.ox.ac.ukInternational Journal of CancerIJCInt. J. Cancer:146,1208–1218 (2020)©2020 The Authors.International Journal of Cancerpublished by John Wiley & Sons Ltd on behalfof UICCCancer EpidemiologySouth Africa, Uganda and Zimbabwe) through the African Cancer Registry Network. Of these,2,311were included for survivalanalyses. The1-,3- and5-year observed and relative survival (RS) were estimated by registry, stage and country-level HDI. Weequally estimated the excess hazards adjusting for potential confounders. Among patients with known stage,64.9% werediagnosed in late stages, with18.4% being metastatic at diagnosis. The RS varied by registry, ranging from21.6%(8.2–39.8)at Year3in Bulawayo to84.5%(70.6–93.5) in Namibia. Patients diagnosed at early stages had a3-year RS of78%(71.6–83.3) in contrast to40.3%(34.9–45.7) at advanced stages (III and IV). The overall RS at Year1was86.1%(84.4–87.6),65.8%(63.5–68.1) at Year3and59.0%(56.3–61.6) at Year5. Age at diagnosis was not independently associated withincreased mortality risk after adjusting for the effect of stage and country-level HDI. In conclusion, downstaging breast cancerat diagnosis and improving access to quality care could be pivotal in improving breast cancer survival outcomes in Africa