This page contains hyperlinks to most of the files associated with the NCI Metathesaurus (NCIm) distribution, the exception being the actual NCIm data files which requires validation of your UMLS credentials. The NCIm is built on top of a subset of the National Library of Medicine's (NLM) UMLS Metathesaurus, use of which is restricted under the UMLS license agreement and requires us to validate your UMLS license. This validation is done from a separate page (see "NCI Metathesaurus Data File Downloads" below).
If you don't have a UMLS account, please request one from the NLM. Follow the "Metathesaurus License" link in the NLM's UMLS Metathesaurus page to request a license.
NCI Metathesaurus Data File Downloads
Please follow the link above to download the NCI Metathesaurus RRF data file distribution. This distribution contains the NCI Metathesaurus version 202008 and is based on the UMLS build 2020AA. To view changes over time click here.
The NCI Metathesaurus in RRF format contains the distribution (over 20 files) of the NCI Metathesaurus in the NLM's Rich Release Format (RRF). Documentation for the RRF is in the UMLS Reference Manual. The NCI Metathesaurus is modeled after the same RRF structure used for the UMLS Metathesaurus. While the table structures are the same, there are differences in the data that is contained in the NCI Metathesaurus versus the UMLS Metathesaurus.
The NCI-specific NLM MetamorphoSys installation is included for a version of NLM's MetamorphoSys that has been configured to work with the NCI Metathesaurus. This version takes into account the NCI's different list of sources and precedence order.
The addendum to NLM's RRF documentation describes NCI-specific changes to the UMLS Metathesaurus RRF structure as follows: any term types, source precedence order, sources, and the relationship attributes in the NCI Metathesaurus that may be different from the UMLS Metathesaurus.