What does "metastasis" mean in oncology?

Metastasis is the spread of cancer cells from the primary tumor site to distant organs or tissues through the bloodstream or lymphatic system. The term comes from meta meaning beyond and stasis meaning standing or placement. The new tumor at the distant site is called a metastatic tumor or secondary tumor and contains the same type of cancer cells as the primary tumor. For example, breast cancer that spreads to the bone is metastatic breast cancer, not bone cancer. Common sites of metastasis include the liver, lungs, brain, and bones.