NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,790 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.

primary cancer
(PRY-mayr-ee KAN-ser)
A term used to describe the original, or first, tumor in the body. Cancer cells from a primary cancer may spread to other parts of the body and form new, or secondary, tumors. This is called metastasis. These secondary tumors are the same type of cancer as the primary cancer. Also called primary tumor.