The ontologymappings service provides equivalency mapping between ICD-O and other classification systems, notably NCIt and UBERON. It makes use of the sample-level mappings for NCIT and ICD-O 3 codes developed for the individual samples in the Progenetix collection.
NCIT and ICD-O 3
While NCIT treats diseases as histologic and topographic described entities (e.g. NCIT:C7700: Ovarian adenocarcinoma), these two components are represented separately in ICD-O, through the Morphology and Topography coding arms (e.g. here 8140/3 + C56.9).
More documentation with focus on the API functionality can be found on the documentation pages.
The data of all mappings can be retrieved trough this API call: {JSON↗}