Variations in Breast Cancer Survival Rates: A Systematic Review and Meta-Analysis of Data from the Entire Continent of Africa

Abstract

Background: The survival from breast cancer in Africa is poor and yet the incidence rate is on the rise. Causes of variations in survival from breast cancer are not well understood. We aimed to do a systematic review and meta-analysis on 5-year survival rates of breast cancer on the entire continent of Africa and to examine trends over time, and investigate sources of variations across the region. Methods: We searched MEDLINE, Embase, Cochrane Library to identify studies on breast cancer survival in African men and women published before October 17, 2018, and in any language. Random-effects meta-analyses were done to investigate between-study heterogeneity in 5-year survival rates of breast cancer and meta-regression analyses to identify potential sources of variation. 5-year survival rates of breast cancer in Africa were compared with similar estimates for black and white population in the USA from the Surveillance, Epidemiology, and End Results database. Findings: 54 studies were included, which consisted of 18,970 women and men from 13 African countries, 8 of which were from sub-Saharan region. There was wide between-study heterogeneity in the survival rates (mean 52.9%, range 7-91%, I2=99.1%; p<0.0001). Age and gender adjusted 5-year survival rates were lower in sub-Saharan Africa (absolute difference [AD] from North Africa [reference group] -25.4% (95% CI: -34.97 to -15.82%), lower in predominantly black population compared to predominantly white population -25.9% lower (95% CI: -35.40 to -16.43%). Within sub-Saharan region, survival rates are lower in western and eastern region compared to southern region. Although triple negative cancer negatively correlated with survival, the correlation did not reach a statistical significance (r=-0.27, p=0.35). Survival rates are increasing over time more in white Africans compared to black Africans but the survival rates for Africans are still significantly lower when compared to the black and white populations in the USA, a high-income country. Interpretation: Region and race-specific public health interventions coupled with genetic prospective studies are urgently needed to improve breast cancer survival Africa. Funding Statement: Support was provided from the unrestricted funds from the Academic Enrichment Fund of the Department of Surgery and the David L. Nahrwold Endowment in the Penn State College of Medicine (DIS). Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: For this systematic review and meta-analysis, the authors developed a study protocol based on the PRISMA guidelines.