The NCI Metathesaurus is product of the US National Cancer Institute's Enterprise Vocabulary Service, a collaborative effort of the NCI Center for Bioinformatics and the NCI Office of Communications. The NCI Metathesaurus is based on NLM's Unified Medical Language System Metathesaurus supplemented with additional cancer-centric vocabulary.
The public version of the NCI Metathesaurus currently contains all public domain vocabularies from the National Library of Medicine's UMLS Metathesaurus, as well as a growing number of NCI-specific vocabularies developed by the National Cancer Institute.
The public version of the NCI Metathesaurus also contains proprietary vocabularies. Certain vocabularies, such as ICD-10 and ICD-O-3, are made available, by permission, for non-commercial use only. Others, specifically MedDRA, are made available subject to license restrictions. See http://www.nlm.nih.gov/research/umls/license.html for details.