Cancer can begin in any organ or tissue of the body. The original tumor is called the primary cancer or primary tumor and is usually named for the part of the body in which it begins. Metastasis means the spread of cancer. Cancer cells can break away from a primary tumor and travel through the bloodstream or lymphatic system to other parts of the body. This is called nodal involvement, positive nodes, or regional disease.
Cancer cells can also spread to other parts of the body, distant from the primary tumor.
Doctors use the term metastatic disease or distant disease to describe cancer that spreads to other organs or to lymph nodes other than those near the primary tumor. When cancer cells spread and form a new tumor, the new tumor is called a secondary, or metastatic, tumor. The cancer cells that form the secondary tumor are like those in the original tumor. A metastasis is a tumor that started from a cancer cell or cells in another part of the body. Sometimes, however, a primary cancer is discovered only after a metastasis causes symptoms.