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Overview of EVS

NCI Enterprise Vocabulary Services (EVS) provides controlled vocabulary that is the semantic base for caCORE, CORE infrastructure, and caBIG tools and collaborations.

EVS, a collaborative effort of the NCI Center for Biomedical Informatics and Information Technology (CBIIT) and the NCI Office of Communications, develops and provides operations support for the NCI Thesaurus (NCIt), a cancer-focused terminology and the NCI Metathesaurus (Meta), a mapping between many terminologies, two broadly used vocabulary sources for cancer research.

EVS also conducts the Biomedical Grid Terminology (BiomedGT) project to enlist participation in developing an open, federated ontology covering translational research. EVS has developed tools to support collaborative community-based ontology development, and is actively seeking subject matter experts from across biomedicine as contributors to BiomedGT.

In addition, EVS licenses and serves third party terminology as needed to meet NCI and caBIG requirements; hosts and contributes to other standards; and works with vendors to create and improve tools for vocabulary development, curation and deployment. EVS from its beginning has sought to address the broad spectrum of terminology needs at NCI.

Architecturally the EVS terminology service is a component of caCORE. The LexEVS 4.2 service is the current release, and LexEVS 5.0 is under development. With that release, the caCORE 3.x APIs and EVS 3.x Grid services will be retired. Refer to the retirement announcement for details.

The EVS/caCORE 4.x service supports the new distributed LexBIG API as well as the older caCORE 3.2 EVS API. Both are supported by the LexBIG server. Because adoption of the LexBIG terminology server is a major change for EVS users, we are continuing to operate the original caCORE 3.2 server as well as the newer EVS/caCORE 4.x server. For both, the caCORE client side APIs provide an open, publicly available, unified interface to EVS services. Effective with caCORE 4.1 EVS surfaced a terminology service node based on the caCORE 3.2 EVS API on caGrid 1.1.

The underlying software code, object model, use cases, and user documentation are available for use under an open-source license. Developers are encouraged visit the EVS download page for the relevant files and licensing information.

The following Enterprise Architect example files are available.

titleContents of this Page
Table of Contents
titleEVS 3.x Retirement

Announcement posted

titleOn the EVS Wiki
titleProject and Product Information
titleAvailability of earlier releases

Files from caCORE EVS version 4.1.x, 4.0, 3.2.1, 3.1,,, 3.0.1, 3.0 are made available for download from the EVS Archives. Note that the 4.x license terms still apply.

The EVS Grid Service 1.0 (pointing to the caCORE 3.1 EVS Services) is still available. It will be decommissioned with next major release of the LexEVS (v5.0). Therefore, the EVS Team encourages migration to the current release of the LexEVS Grid Service (v4.2). As of the 4.1 Release of the EVS Grid Service, the service is no longer part of the caGrid infrastructure and has been deployed as a separate unit. For access to the EVS 4.1 Grid Service, visit the EVS Archives. Note that the 4.x license terms still apply.

Semantics of NCI Terminology (NCIt)

NCIt provides four features which together provide proven sufficient basis for the semantic integration of the caCORE. These four features are:

  • Permanent, non-semantic concept codes
  • NCI preferred terms for each concept
  • English language definitions
  • Synonyms

More complete description of the semantics of NCIt has been posted. A document briefly describing the editorial policies governing change to NCIt content is included with the semantics information.

Using the EVS Wiki

This is the wiki home page for the EVS products. EVS developers may edit this page and any user may add a comment

About EVS

Since 1997, NCI Enterprise Vocabulary Services (EVS) has provided terminology content, tools, and services to accurately code, analyze and share cancer and biomedical research, clinical care, and public health information. EVS works with many partners to develop, license and publish terminology, jointly develop software tools, and support harmonization and shared standards. EVS provides the foundational layer for NCI's informatics infrastructure, and plays an important role in federal and international standards efforts (see EVS Use and Collaborations).

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EVS Terminology

EVS creates, compiles, and cross-maps biomedical terminology needed by NCI and its community. EVS publishes NCI Thesaurus (NCIt) as its core reference terminology and biomedical ontology, as well as NCI Metathesaurus (NCIm), which provides cross-mappings to more than 110 terminologies.  EVS also makes available standalone versions of other terminologies and ontologies, as well as many specialized mappings and value sets.

  • NCI Thesaurus (NCIt) is NCI's reference terminology and core biomedical ontology, covering more than 170,000 key biomedical concepts with a rich set of terms, codes, 150,000 textual definitions, and over 900,000 inter-concept relationships. NCIt combined and extended core NCI terminologies within a scientifically and technically rigorous framework. NCIt is now a broadly shared coding and semantic infrastructure resource – over half of NCIt concepts include content explicitly tagged by one or more EVS partners (for additional information including detailed statistics see the shared terminology development wiki page ).
  • NCI Metathesaurus (NCIm) provides a broad, concept-based mapping of terms from over 110 biomedical terminologies, whose 8,700,000 terms are mapped to 3,600,000 concepts representing their shared meanings. NCIm contains most terminologies used by NCI for clinical care, translational and basic research, and provides a rich source of definitions, synonyms, codes, and other information. NCIm starts from a subset of NLM's UMLS Metathesaurus, and modifies and extends it with many additional sources.
  • Other Terminologies : EVS licenses, processes and makes available individually through EVS systems, many other terminologies of special interest to NCI and the research community. EVS has helped create, harmonize with, and publish several of these terminologies.  NCI Term Browser publishes all terminologies hosted by NCI EVS in an integrated environment, providing search, cross-links, and a user friendly interface to ICD-10-CM, CTCAE, MedDRA, SNOMED CT, MED-RT, GO, and many other terminologies and ontologies used by NCI and its partners.
  • Terminology Mappings : Pairwise mappings between several supported terminologies have also been created and published to support data translation and cross-reference. As with standalone terminologies above, such mappings generally reflect special EVS community interests and collaborations.
  • Terminology Value Sets and Data Standards: EVS works with many partners to create and support standardized terminology for biomedical coding.  Hundreds of NCIt subsets and other code lists are maintained by EVS, and most are now available as CTS 2 value sets following the draft Common Terminology Services Release 2 (CTS 2) specification . In caDSR, they provide a pre-curated standard set of meanings for use by metadata curators.  More than 1300 value sets are currently defined in EVS, most as subsets of NCIt covering a range of standards from many EVS partners.  Key EVS supported terminology standards include:
    • FDA Terminology : EVS is working with the U.S. Food and Drug Administration (FDA) to develop and support controlled terminology in several areas. More than 25,000 FDA terms and codes are stored in NCIt.

    • CDISC Terminology : The Clinical Data Interchange Standards Consortium (CDISC) -- an international, non-profit organization that develops and supports global data standards for medical research -- has chosen EVS as its terminology partner.

    • NCPDP Terminology : The National Council for Prescription Drug Programs (NCPDP) creates and promotes the transfer of data related to medications, supplies, and services through the development of standards and industry guidance, and now uses NCIt in two of its standards.

    • Pediatric Terminology : The National Institute of Child Health and Human Development (NICHD) and EVS are working with numerous contributors from national and international academic, clinical and research institutions to provide standardized terminology for coding pediatric clinical trials and other research activities.

Making these terminology resources more easily available, mapping between them, harmonizing coding standards, and promoting agreement on best practices, are all core EVS priorities.