Controlled terminologies and ontologies provide the underlying foundation for data integration, sharing and re-use, and knowledge management. This common vocabulary is an essential part of making data consistent and interoperable. These efforts promote harmonization and shared standards across NCI’s informatics infrastructure. 

NCI manages and distributes cancer vocabulary through NCI Enterprise Vocabulary Services (EVS). The EVS team creates and maintains the vocabulary, made up of several different terminologies and ontologies which are organized and connected in different ways. This process involves working with many partners to develop, license, and publish terminology and jointly develop software tools.

New terms are added and analysis tools are created in response to the needs of the research community.

Submit a New Term

We’re collecting feedback on content or structure of existing items and contributions for new terms to be used by NCI, EVS, and partner terminology products.

Terminologies and Ontologies

Consistent vocabulary in the form of individual pieces of terminology or mapped concept ontologies are the core of EVS.

NCI Thesaurus

NCI’s core reference terminology and biomedical ontology is collected in the NCI Thesaurus (NCIt). It covers more than 140,000 key biomedical concepts with terms and codes, 120,000 written definitions, and more than 500,000 inter-concept relationships.

The Thesaurus can be accessed through the NCI Thesaurus Browser or the NCI Term Browser. Content can also be retrieved via API or downloaded.

NCI Metathesaurus

NCIm is based on the National Library of Medicine’s Unified Medical Language System Metathesaurus (UMLS) but has been modified and extended with many additional sources.

The NCI Methathesaurus can be accessed through the NCI Metathesaurus Browser or the NCI Term Browser. Content can also be retrieved via API or downloaded

Reference Terminologies and Ontologies

EVS currently maintains more than 22 standalone terminologies and ontologies of special interest to NCI and the research community. EVS has helped create and harmonize several of these terminologies, which originate from other agencies and standards development organizations such as the Food and Drug Administration (FDA) and Clinical Data Interchange Standards Consortium (CDISC).

These terminologies can be searched and browsed through the NCI Term Browser.

Terminology Value Sets

Value sets are a pre-curated, standard set of meanings that can be used for biomedical coding. EVS and its partners have developed and now maintain more than 1,000 user-specific and generalized value sets.

Value Sets can be searched, browsed, and downloaded through the Value Sets tab in the NCI Term Browser.

Several of the key value sets are:

Food and Drug Administration Terminology

EVS works with the U.S. Food and Drug Administration (FDA) to develop and support controlled terminology in several areas. More than 15,000 FDA terms and codes are stored in NCIt and tagged and published as value sets.

Clinical Data Interchange Standards Consortium Terminology

The Clinical Data Interchange Standards Consortium (CDISC) is an international non-profit organization that develops and supports global data standards for medical research.

NCIt Neoplasm Core Terminology

The NCIt Neoplasm Core value set provides a core reference set of NCIt neoplasm classification concepts that is designed to facilitate consistent coding, analysis, and data sharing across a broad range of NCI and related resources. These files provide a comprehensive collection of key terms, definitions, simplified hierarchies, mappings to dozens of other terminologies, and molecular characteristics, all linked back to online EVS resources.

Terminology used in NCI Clinical Trials Search Reporting Program

EVS provides semantic support to NCI’s Clinical Trials Reporting Program (CTRP) to enable consistent and accurate clinical trial abstraction, coding, reporting, and portfolio management for internal NCI usage and effective clinical trial search – for patients and providers. EVS develops, maintains, and publishes more than 20,000 concepts covering diseases, drugs, interventions, biomarkers, and demographics.

The National Council for Prescription Drug Programs 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. It uses NCIt in two of its standards.

National Institute of Child Health and Human Development Terminology

The National Institute of Child Health and Human Development (NICHD) and EVS have worked 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.  This terminology is included in NCIt and tagged as value sets for viewing or download.

Terminology Mappings

Terminology Mappings are curated, paired mappings between several supported terminologies to support data translation and cross-referencing. Mappings continue to be created based on the interests and needs of the research communities.

Terminology Mappings can be searched, browsed, and downloaded through the Mappings tab in the NCI Term Browser.

Accessing NCI Terminology Content


The NCI Term Browser publishes all terminologies hosted by EVS in an integrated environment, providing search support, cross-links, and a user-friendly interface. Within the term browser, you can access terminology Mappings and Value Sets.

The NCI Thesaurus and NCI Metathesaurus also have their own browsers.

Back-end Services and Open Source Software


LexEVS is the EVS terminology server. It comprises a collection of software and services for loading, publishing, and providing access to vocabulary and ontology resources. The Mayo Clinic developed LexEVS as an open-source tool with NCI support. Many NCI and external applications, including the cancer Data Standards Registry and Repository (caDSR), use the server's application programming interfaces (APIs).

We’re currently working on a new EVS API to provide easier, faster access.

NCI Protégé

NCI Protégé is the primary EVS editing software application. It is based on Stanford University's open-source Protégé tool. NCI developed Protégé plug-ins to meet EVS requirements and business rules, then contributed the code back to the community to foster further Protégé adoption.

For a full list of tools and downloads, visit the EVS website.

The EVS wiki provides a greater level of technical detail about terminology tools and resources.

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