Metastasis, or
metastatic disease, is the spread of a
cancer or other disease from one
organ or part to another not directly connected with it. The new occurrences of disease thus generated are referred to as
metastases (sometimes abbreviated "mets"). It was previously thought that only
malignant tumor cells and
infections have the capacity to
metastasize (also spelled metastasise); new research has caused this to be reconsidered. The existence of metastatic cancers in the absence of primary tumors also suggests that metastasis is not always caused by malignant cells that leave primary tumors.
Metastasis is a
Greek word meaning "displacement", from μετά,
meta, "next", and στάσις,
stasis, "placement".