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 carcinoma of unknown primary.

Source: NCI Dictionary of Cancer Terms

Caption: In carcinoma of unknown primary, cancer cells have spread in the body but the place where the primary cancer began is unknown.

2006-12-21 Date last modified: 2015-03-30