Overview of the NCI Metathesaurus (NCIm)
NCI Metathesaurus (NCIm) (download) is a wide-ranging biomedical terminology database that covers most terminologies used by NCI for clinical care, translational and basic research, and public information and administrative activities.
The database contains approximately 3,000,000 concepts mapped to 7,400,000 terms with 24,000,000 relationships with more than 100 sources. NCIm contains most public domain vocabularies from the National Library of Medicine's UMLS Metathesaurus, as well as many other biomedical vocabularies. Some propriety vocabularies are included, and have restrictions on their use.
NCIm is intended to provide rich synonymy and is useful in mapping among the codes and terms used in various biomedical vocabularies. In contrast the NCI Thesaurus (NCIt) is the NCI reference vocabulary that provides the concepts used in caCORE and caBIG® to establish data semantics.
NCIm is registered in the HL7 OID Registry 
as 2.16.840.1.113883.3.26.1.2 .
NCIm is published twice a year. Each build is created using the most recent release of the UMLS Metathesaurus, dropping some old and restricted sources, adding many NCI-specific sources, and following NCI editorial policies. The availability of new builds, and the differences between builds, are announced on the NCI EVS list server.
In addition to the NCIm and the NCIt, the EVS servers provide access to a variety of other vocabulary products such as MedDRA, CTCAE, GO, ICD-9-CM, RadLex, SNOMED CT, LOINC and MED-RT.
Additional Information
How to Provide Comments and Suggestions
Comments and suggestions may be emailed to the NCIm team at NCIMetathesaurus@mail.nih.gov.
