# NCI Thesaurus (NCIt)

Source: https://onco.cc/terms/ncit/  
OnCo record `ncit` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The NCI Thesaurus is the US National Cancer Institute's reference vocabulary of diseases, drugs, anatomy and findings, each with a stable code such as C4872 for breast carcinoma.

## Summary

The NCI Thesaurus, published by the National Cancer Institute (Wikipedia describes the NCI as the coordinator of the US National Cancer Program), is a reference terminology covering cancers, drugs, anatomy, genes and clinical findings, with definitions, synonyms and codes updated monthly. ClinicalTrials.gov conditions, FDA drug terminology and OncoTree map to it, so it is the natural spine for joining trials, drugs and diagnoses across sources.

## Fields

- Kind: Term
- Last checked: 2026-09-24
- Also known as: NCI Thesaurus; NCIt; NCIt code; NCIt concept; NCI terminology
- Tags: cansim-terms

## Notes

- Listed in the CanSim terms map 1.0.0 (docs/onco/terms.json, generated 2026-09-24), CC BY 4.0, attribution: CanSim project, an open, public-data-first cancer foundation-model programme; CanSim page path /terms/ncit.

## Sources

- NCI Thesaurus browser: https://ncithesaurus.nci.nih.gov/ncitbrowser/
- Wikipedia: National Cancer Institute: https://en.wikipedia.org/wiki/National_Cancer_Institute

## Connected records

- terms: [Cancer AI vocabulary (CanSim terms map)](https://onco.cc/terms/cancer-ai-vocabulary/), [Human Phenotype Ontology (HPO)](https://onco.cc/terms/hpo/), [ICD-O-3 (International Classification of Diseases for Oncology)](https://onco.cc/terms/icd-o-3/), [Mondo disease ontology](https://onco.cc/terms/mondo/), [OncoTree cancer classification](https://onco.cc/terms/oncotree-term/), [RxNorm drug nomenclature](https://onco.cc/terms/rxnorm/)

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JSON: https://onco.cc/api/v1/entities/ncit.json