ICD-O-3
Online version of ICD-O from International Agency of Research on Cancer (IARC)
Online downloadable CSV version of ICD-O-3 from WHO (does not contain 2011 ICD-O-3.1 updates)
Guidance documents from NAACCR on now to implement ICD-O-3.1
Mapping of oncology diagnosis using NCI Metathesaurus
Memorial Sloan Kettering (MSK) Oncotree mapping
MSK & collaborator's tumor terminology (publicly available): http://oncotree.mskcc.org/oncotree/
Public API that maps ICDO site and histology combinations to Oncotree concepts, which at the same time are mapped to NCI Thesaurus and UMLS: http://oncotree.mskcc.org/oncotree-mappings/
An example of an API call: http://oncotree.mskcc.org/oncotree-mappings/crosswalk?vocabularyId=ICDO&conceptId=&histologyCode=8490/3&siteCode=C16.1