American Cancer Society; Centers for Disease Control and Prevention; Swiss Re; Swiss Cancer Research foundation; Swiss Cancer League; Institut National du Cancer; La Ligue Contre le Cancer; Rossy Family Foundation; US National Cancer Institute; and the Susan G Komen Foundation.

BACKGROUNDThe third edition of the International Classification of Diseases for Oncology (ICD‐O‐3), which was published in 2000, introduced major changes in coding and classification of neoplasms, notably for leukemias and lymphomas, which are important groups of cancer types that occur in childhood. This necessitated a third revision of the 1996 International Classification of Childhood Cancer (ICCC‐3).METHODSThe tumor categories for the ICCC‐3 were designed to respect several principles: agreement with current international standards, integration of the entities defined by newly developed diagnostic techniques, continuity with previous childhood classifications, and exhaustiveness.RESULTSThe ICCC‐3 classifies tumors coded according to the ICD‐O‐3 into 12 main groups, which are split further into 47 subgroups. These 2 levels of the ICCC‐3 allow standardized comparisons of the broad categories of childhood neoplasms in continuity with the previous classifications. The 16 most heterogeneous subgroups are broken down further into 2–11 divisions to allow study of important entities or homogeneous collections of tumors characterized at the cytogenetic or molecular level. Some divisions may be combined across the higher‐level categories, such as the B‐cell neoplasms within leukemias and lymphomas.CONCLUSIONSThe ICCC‐3 respects currently existing international standards and was designed for use in international, population‐based, epidemiological studies and cancer registries. The use of an international classification system is especially important in the field of pediatric oncology, in which the low frequency of cases requires rigorous procedures to ensure data comparability. Cancer 2005. © 2005 American Cancer Society.

No abstract