Breast cancer survival in sub-Saharan Africa by age, stage at diagnosis and human development index: A population-based registry 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 obtained data on a random sample of 2,588 breast cancer incident cases, diagnosed in 2008-2015 from 14 population-based cancer registries in 12 countries (Benin, Cote d'Ivoire, Ethiopia, Kenya, Mali, Mauritius, Mozambique, Namibia, Seychelles, South Africa, Uganda and Zimbabwe) through the African Cancer Registry Network. Of these, 2,311 were included for survival analyses. The 1-, 3- and 5-year observed and relative survival (RS) were estimated by registry, stage and country-level HDI. We equally estimated the excess hazards adjusting for potential confounders. Among patients with known stage, 64.9% were diagnosed in late stages, with 18.4% being metastatic at diagnosis. The RS varied by registry, ranging from 21.6%(8.2-39.8) at Year 3 in Bulawayo to 84.5% (70.6-93.5) in Namibia. Patients diagnosed at early stages had a 3-year RS of 78% (71.6-83.3) in contrast to 40.3% (34.9-45.7) at advanced stages (III and IV). The overall RS at Year 1 was 86.1% (84.4-87.6), 65.8% (63.5-68.1) at Year 3 and 59.0% (56.3-61.6) at Year 5. Age at diagnosis was not independently associated with increased mortality risk after adjusting for the effect of stage and country-level HDI. In conclusion, downstaging breast cancer at diagnosis and improving access to quality care could be pivotal in improving breast cancer survival outcomes in Africa.

Keywords: Africa; breast cancer; human development index; stage; survival.