NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,812 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.

principal investigator
(PRIN-sih-pul in-VES-tih-GAY-ter)
The person(s) in charge of a clinical trial or a scientific research grant. The principal investigator prepares and carries out the clinical trial protocol (plan for the study) or research paid for by the grant. The principal investigator also analyzes the data and reports the results of the trial or grant research. Also called PI.