NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,791 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.

proton beam radiation therapy
(PROH-ton beem RAY-dee-AY-shun THAYR-uh-pee)
A type of radiation therapy that uses streams of protons (tiny particles with a positive charge) to kill tumor cells. This type of treatment can reduce the amount of radiation damage to healthy tissue near a tumor. It is used to treat cancers of the head and neck and organs such as the brain, eye, lung, spine, and prostate. Proton beam radiation is different from x-ray radiation.