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Leukemia: Cancer that starts in blood-forming tissue such as the bone
marrow and causes large numbers of blood cells to form and enter the
bloodstream.
Malignant: Cancer. Malignant tumors can invade nearby tissue and
spread to other parts of the body.
Metastasis: The spread of cancer from one part of the body to another.
A tumor formed by cells that have spread is called a metastatic tumor or
a metastasis. The metastatic tumor contains cells that are like those in
the original (primary) tumor.
Radiation therapy: The use of high-energy radiation from x-rays,
gamma rays, neutrons, protons, and other sources to destroy cancer
cells and shrink tumors. Radiation may come from a machine outside the
body (external-beam radiation therapy), or it may come from radioactive
material placed in the body near cancer cells (internal radiation therapy).
Recurrence: Cancer that has recurred (come back), usually after a
period of time during which the cancer could not be detected. The cancer
may come back to the same place as the original (primary) tumor or to
another place in the body. Also called recurrent cancer.
Relapse: The return of cancer after a period of improvement.
Remission: A decrease in or disappearance of signs and symptoms of
cancer. In partial remission, some, but not all, signs and symptoms of
cancer have disappeared. In complete remission, all signs and symptoms
of cancer have disappeared, although cancer still may be in the body.
Risk factor: Something that increases the chance of developing a
disease. Some examples of risk factors for cancer are age, a family
history of certain cancers, use of tobacco products, being exposed to
radiation or certain chemicals, infection with certain viruses or bacteria,
and certain genetic changes.
Side effect: A problem that occurs when treatment affects healthy
tissues or organs. Some common side effects of cancer treatment are
fatigue, pain, nausea, vomiting, decreased blood cell counts, hair loss,
and mouth sores.