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.

topoisomerase inhibitor
(TOH-poh-i-SAH-meh-rays in-HIH-bih-ter)
A substance that blocks topoisomerases (enzymes that break and rejoin DNA strands and are needed for cells to divide and grow). Blocking these enzymes may kill cancer cells. Certain topoisomerase inhibitors are being studied in the treatment of cancer.