Summary: 

The International Classification of Diseases for Oncology (ICD-O) is internationally recognized as the definitive classification of neoplasms. The third edition of ICD-O (ICD-O-3) and its 2011 update (ICD-O-3 First Revision, or ICD-O-3.1) have now been made available by the International Agency for Research on Cancer as online, fully searchable electronic resources. An efficient search tool enables the user to quickly identify specific entities. In addition, the listings are enhanced with useful definitions of entities from the WHO/IARC Classification of Tumours series and other sources.