NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,863 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.

phase III clinical trial
(fayz … KLIH-nih-kul TRY-ul)
A study that tests the safety and how well a new treatment works compared with a standard treatment. For example, phase III clinical trials may compare which group of patients has better survival rates or fewer side effects. In most cases, treatments move into phase III trials only after they meet the goals of phase I and II trials. Phase III clinical trials may include hundreds of people.