NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,780 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.

actinic keratosis
(ak-TIH-nik KAYR-uh-TOH-sis)
A thick, scaly patch of skin that may become cancer. It usually forms on areas exposed to the sun, such as the face, scalp, back of the hands, or chest. It is most common in people with fair skin. Also called senile keratosis and solar keratosis.