NCI Thesaurus is NCI's core reference terminology. Over the last 10 years, it has also been adopted by FDA, CDISC, NCPDP and other partners as a shared standards development and coding environment, allowing participants to compare and harmonize with each other's content while taking advantage of full-text definitions, codes, and other features.

About 40,000 out of the nearly 100,000 current NCIt concepts have terms from both EVS and from one or more of these other sources. The chart below gives the last available detailed breakdown, for June 2010. Note that some partners have used NCI terms rather than tagging their own, so these figures understate the true extent of cross-source sharing.

Figure 26. NCIt concepts with terms from tagged outside sources (10.06e: June 2010)