NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,916 terms related to cancer and medicine.

Browse the dictionary by selecting a letter of the alphabet or by entering a cancer-related word or phrase in the search box.

tumor initiation
(TOO-mer ih-NIH-shee-AY-shun)
A process in which normal cells are changed so that they are able to form tumors. Substances that cause cancer can be tumor initiators.