NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,811 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.

antagonist
(an-TA-guh-nist)
In medicine, a substance that stops the action or effect of another substance. For example, a drug that blocks the stimulating effect of estrogen on a tumor cell is called an estrogen receptor antagonist.