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These FAQs are provided by the Vocabulary Knowledge Center.

What is the difference between the NCI Thesaurus and the NCI Metathesaurus?

The vocabularies are different in a number of areas including origins, format, license, and coverage. To see all the differences look at this comparison.

How do I obtain a copy of the NCI Thesaurus from the UMLS Metathesaurus?

A copy of the NCI Thesaurus can be generated from the UMLS Metathesaurus using the MetamorphoSys tool that comes with the UMLS. The version of the NCI Thesaurus in the UMLS Metathesaurus will lag the current production release of the Thesaurus, so if timeliness is in issue for you, please visit the download center to download the NCI Thesaurus as a standalone vocabulary.  The NCI Thesaurus can also be extracted from the NCI Metathesaurus using MetamorphoSys, which will have a more recent version than that in the UMLS Metathesaurus.

On the download landing page scroll down and click on the NCI Thesaurus link. There are several formats available for download: OWL asserted, OWL inferred, and flat file. Decide which version you want and follow the link to the download page. If you are downloading the NCI Metathesaurus, you will need a UMLS license and there will be directions on how to obtain one from the NLM.

I am trying to find out what "Semantic Type" means in the NCIt and what they each mean. Can you help me?

The information you are looking for is about the UMLS Semantic Types which are part of the UMLS Semantic Network.

Follow this links for information on the Semantic Types.

This page provides a chart of the Semantic Types and their hierarchies: Semantic Types and Hierarchy.

How do I contribute concepts or make a terminology suggestion for inclusion in the NCI Thesaurus?

  • For a substantial volume of terms, or a subtree, the easiest way would be to send a spreadsheet to the editors, with contact information. That can be sent to They will assign it and interact with the submitter.
  • Alternatively, and the best route for a small numbers of terms, use the Term Suggestion feature on the Quick Links pull down on the NCI Thesaurus browser.

Other questions

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