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Question: 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 like including origins, format, license, and coverage, and more. To see all the differences look at our this comparison.Question:

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 NCI EVS Download site at
EVS Portalthe 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 to the section and click on the NCI Thesaurus link. There are several formats available for
download; : OWL asserted, XML (both the OWL inferred and asserted versions in a format suitable for use in Apelon DTS) and , and flat file. Decide which version you want and follow the link to the download page. You will be routed thru a registration and then a license page before you come to the actual download page. You can register as a user if you want, but you don't have to. You do need to acknowledge the license terms and conditions (basically under the license you can do anything you want with the NCI Thesaurus content except to change it while still calling it NCI Thesaurus.)Question: 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



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

This url will give you Follow this links for information on the Semantic Types.

This page will give you provides a chart of the Semantic Types and their hierarchies. : Semantic Types and Hierarchy.Question:

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 ncicbmb@mail They will assigned assign it and interact with the submitter.
  • You can also add a note to a concept in the NCIt loaded in NCBO Bioportal. NCI has an RSS feed that will notify them.
  • 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

If your question was not answered on this page, please start a new thread in the Vocabulary Knowledge Center forum for this terminologycontact us at