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NCI Dictionary of Cancer Terms


carcinoma of unknown primary  listen  (KAR-sih-NOH-muh ... UN-none PRY-mayr-ee)

  A case in which cancer cells are found in the body, but the place where the cells first started growing (the origin or primary site) cannot be determined. Also called cancer of unknown primary origin and CUP.

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Carcinoma of unknown primary; drawing shows a primary tumor that has spread from an unknown site to other parts of the body (the lung and the brain). An inset shows cancer cells spreading from the primary cancer, through the blood and lymph systems, to another part of the body where a metastatic tumor has formed.