This supplementary appendix provides detailed information about the data sources and quality metrics used in the study of international childhood cancer incidence from 2001 to 2010. Fourteen pediatric cancer registries and 129 cancer registries in 63 countries contributed data for the 0-14 age group, while 141 registries in 53 countries provided data for the 15-19 age group. The datasets were primarily based on microscopically verified cases, with varying percentages of cases ascertained from death certificates. The appendix includes tables detailing the contribution of individual registries, weights used for age-standardized rates, incidence rates by world region, and the distribution of tumor types. It also provides a comprehensive list of contributors from various countries, including Africa, Latin America, North America, Asia, and Europe.This supplementary appendix provides detailed information about the data sources and quality metrics used in the study of international childhood cancer incidence from 2001 to 2010. Fourteen pediatric cancer registries and 129 cancer registries in 63 countries contributed data for the 0-14 age group, while 141 registries in 53 countries provided data for the 15-19 age group. The datasets were primarily based on microscopically verified cases, with varying percentages of cases ascertained from death certificates. The appendix includes tables detailing the contribution of individual registries, weights used for age-standardized rates, incidence rates by world region, and the distribution of tumor types. It also provides a comprehensive list of contributors from various countries, including Africa, Latin America, North America, Asia, and Europe.