This supplementary appendix is part of the original submission and has been peer-reviewed. It provides additional information for the study "International incidence of childhood cancer, 2001–10: a population-based registry study" published in The Lancet Oncology. The appendix includes tables and figures that support the main study. Table S1 describes the contribution of individual cancer registries to the study datasets. It lists the cancer registries included in the analyses, noting that some registries cover patients younger than 15 years (paediatric dataset) and others cover patients younger than 20 years (general dataset). The data from paediatric registries are prioritized when they co-exist with general registries in the same country. The study includes data from 129 cancer registries in 63 countries in the paediatric dataset and 141 registries in 53 countries in the general dataset. Most registries have between 80% and 98% of cases microscopically verified, with some having lower or higher verification rates. The study also notes that some registries could not ascertain cases from death certificates due to lack of access or systematic collection. Table S2 provides the weights of the World standard population used to calculate age-standardised rates. Table S3 presents the numbers of cases and incidence rates per million by world region. Table S4 provides an overview of the data included in the comparison of cancer incidence in children aged 0-14 years in the 1980s and the present study. Figures S1-S3 show variations in sex ratios, age-specific rates, and tumour type distributions by world region. The data for these figures are based on the paediatric and general datasets. The appendix also includes a list of contributors to the International Incidence of Childhood Cancer (IICC-3) study, detailing the countries and registries involved. The contributors include registries from Africa, Latin America and the Caribbean, North America, Asia, Europe, and Oceania. The appendix concludes with references to the studies and data sources used in the research.This supplementary appendix is part of the original submission and has been peer-reviewed. It provides additional information for the study "International incidence of childhood cancer, 2001–10: a population-based registry study" published in The Lancet Oncology. The appendix includes tables and figures that support the main study. Table S1 describes the contribution of individual cancer registries to the study datasets. It lists the cancer registries included in the analyses, noting that some registries cover patients younger than 15 years (paediatric dataset) and others cover patients younger than 20 years (general dataset). The data from paediatric registries are prioritized when they co-exist with general registries in the same country. The study includes data from 129 cancer registries in 63 countries in the paediatric dataset and 141 registries in 53 countries in the general dataset. Most registries have between 80% and 98% of cases microscopically verified, with some having lower or higher verification rates. The study also notes that some registries could not ascertain cases from death certificates due to lack of access or systematic collection. Table S2 provides the weights of the World standard population used to calculate age-standardised rates. Table S3 presents the numbers of cases and incidence rates per million by world region. Table S4 provides an overview of the data included in the comparison of cancer incidence in children aged 0-14 years in the 1980s and the present study. Figures S1-S3 show variations in sex ratios, age-specific rates, and tumour type distributions by world region. The data for these figures are based on the paediatric and general datasets. The appendix also includes a list of contributors to the International Incidence of Childhood Cancer (IICC-3) study, detailing the countries and registries involved. The contributors include registries from Africa, Latin America and the Caribbean, North America, Asia, Europe, and Oceania. The appendix concludes with references to the studies and data sources used in the research.