NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,800 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.

colonoscopy
(KOH-luh-NOS-koh-pee)
Examination of the inside of the colon using a colonoscope, inserted into the rectum. A colonoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue to be checked under a microscope for signs of disease.

EnlargeColonoscopy; shows colonoscope inserted through the anus and rectum and into the colon.  Inset shows patient on table having a colonoscopy.

Colonoscopy. A thin, lighted tube is inserted through the anus and rectum and into the colon to look for abnormal areas.