Childhood cancer survival in low- and middle-income countries and the Global South: emerging evidence and critical gaps from a scoping review of observational studies.

Background: Survival rates for childhood cancer reveal stark global disparities. While over 80 % of children survive in high-income countries (HICs), outcomes remain significantly lower in low- and middle-income countries (LMICs), where the burden is also higher. This study synthesizes observational data on survival outcomes for the six WHO Global Initiative for Childhood Cancer (GICC) index cancers in LMICs, aiming to establish survival estimates, identify key determinants, and assess data limitations. Methods: Following JBI and PRISMA-ScR guidelines, we conducted a scoping review searching MEDLINE, WHO Global Index Medicus, and EMBASE for observational studies published since 2013. Studies included children aged 0-19 diagnosed with acute lymphoblastic leukemia, Burkitt lymphoma, Hodgkin lymphoma, low-grade glioma, retinoblastoma, or Wilms tumor in LMICs. Results: From 6358 records, 196 studies were included. Most (72.9 %) were retrospective cohorts; 71.9 % were single-institution studies. The most frequently reported cancers were acute lymphoblastic leukemia (35.2 %) and Wilms tumor (29.1 %). Mean reported overall survival varied widely, from 62.5 % for Burkitt lymphoma (range 20.0-92.0 %) to 78.6 % for Hodgkin lymphoma (range 40.0-96.6 %). Median follow-up was often poorly reported. Socioeconomic barriers, limited healthcare access, and diagnostic delays were common determinants of poor outcomes. Only 10 % of studies referenced hospital-based registries, and fewer than 5 % used population-based data, highlighting critical data gaps. Conclusions: This review underscores emerging evidence and persistent limitations in childhood cancer survival data from LMICs. The predominance of single-center, retrospective studies indicates a need for more standardized, collaborative research.