Here is the response I received from SNOMED regarding mapping ICD-O-3 axes to SNOMED codes and ICD-O-3 site/histology parings to precoordinated SNOMED clinical findings disorder/diseases. The questions was basically a rehash of my prior forum post.
Thank you for your mail with the subject "Mapping ICD-O-3 Site/Histology Parings to pre-coordinated SNOMED codes", within the SNOMED International customer support system.
First, we would like to explain the approach for the mappings between SNOMED CT and ICD-O.
All morphological codes in ICD-O version 3.1 publication have been included as morphologic abnormalities in SNOMED CT.
The directional maps from SNOMED CT to ICD-O are provided in the Simple Map refset.
They are one-to-one or many-to-one maps due to the granularity differences between two systems.
For example, some are synonyms in ICD-O codes but they are subconcepts in SNOMED CT.
Furthermore, there are also morphologies in SNOMED CT that are not covered by ICD-O codes.
All topographical codes in ICD-O version 3.1 publication have been used as target of mapping for body structure concepts in SNOMED CT.
The topographical codes from ICD-O are not sufficient for SNOMED CT concept modeling for disorders.
Currently, 22,826 body structure concepts are mapped to 287 ICD-O codes.
These maps are incomplete because there are potentially additional 3,000 body structures to be mapped to ICD-O codes.
Please let us know if we have missed any ICD-O codes in version 3.1. We have also planned to include ICD-O version 3.2 when we receive the finalised release from WHO.
We haven't taken the approach to pre-coordinate disorders in SNOMED CT by combination of ICD-O morphologies and topographical codes.
The combination can be fully supported by post-coordination based on SNOMED CT concept model.
Currently, disorders are added when we receive customer requests.
These are the key reasons that disorders do not have full coverage for all ICD-O combinations.
Regarding what have been covered by disorders, 4,481 disorders have been modeled by morphologies mapped to ICD-O codes with SNOMED CT body structures that are subconcepts of ICD-O topographical codes.
If we ignore body structures, there are about 5,000 disorders that are modelled by ICD-O morphologies.
It is about 10% of your estimated possible combinations by ICD-O sites and morphologies.
We would like understand your requirement for pre-coordination for all combinations.
In particular, the explanations for reasons and applications from professional bodies and user groups would help us to prioritise the requirement for future content authoring.