carcinoma of unknown primary

Definition of carcinoma of unknown primary
National Cancer Institute

carcinoma of unknown primary

(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.

Source: NCI Dictionary of Cancer Terms