The NCIt is developed in OWL using NCI-developed plug-ins for the Protege editor, hence OWL is the primary distribution format and we provide asserted and inferred versions. We also provide the NCIt in a tab-delimited format that some users prefer over XML for simple purposes.
In the files below, the asserted version contain is-a and role relations as stated by the editors of the NCIt (except in the case of the tab-delimited file where role relations are excluded). The inferred version is the result of classification, and contains inferred is-a and role relations, as well as the asserted relations. In addition, annotations meant to support NCIt editors, e.g. editor notes, are excluded from all files.
Please see the ReadMe.txt file for more information on the download formats. Periodically it might contain additional information specific to a particular release version of the NCIt.
NCI Thesaurus Downloads
Current Version: Editing of NCI Thesaurus 21.03e was completed on March 29, 2021. Version 21.03e was March's fifth build in the development cycle.
Thesaurus_21.03e.OWL.zip in OWL format (asserted version). This file contains the entire terminology expressed in OWL. The rdf:about (rdf:ID) utilizes semantically meaningless identifiers, e.g. "C123456", which is also the value of the "code" property. The rdf:about of annotation and object properties are also replaced with their corresponding codes. This is the version of the NCIt that after classification (to generate an inferred version) is loaded into the LexEVS terminology server to support API and web browser access.
ThesaurusInf_21.03e.OWL.zip in OWL format (inferred version). This file is created for import into the UMLS and NCI Metathesaurus and excludes retired concepts. It uses semantically meaningless rdf:about identifiers as described above for the "asserted version".
Thesaurus_21.03e.FLAT.zip in tab-delimited format (asserted version). This file includes is-a relations, synonyms, and NCI definitions, but excludes roles and the rest of the annotation properties.
For previous releases of the NCI Thesaurus, browse the Archives.