Metastatic Bone Cancer

Metastatic bone cancer -- cancer that starts somewhere else in the body and then spreads to the bone -- is much more common than primary bone cancer. Although any type of cancer can spread to the bone, the most common types are those of the breast, lung, kidney, thyroid, and prostate. Bone metastases most often arise in the hip, femur (thighbone), shoulder, and spine. Like other types of cancer, those that start in the bone can also spread to other parts of the body. The remainder of this overview focuses on the primary bone cancers osteosarcoma and Ewing's sarcoma.


SYMPTOMS
The most common symptom of bone cancer is pain, which is caused either by the spread of the tumor or by the breaking of bone that is weakened by a tumor. Stiffness or tenderness in the bone may also occur. Sometimes there are other symptoms, such as fatigue, fever, swelling, and stumbling.
But these symptoms can also be caused by other conditions. Only a doctor can tell for sure whether or not a patient has bone cancer.


DIAGNOSIS
As with most illnesses, the first part of the diagnosis of suspected bone cancer is a discussion with the doctor about the patient's personal and family medical history. Then the doctor performs a complete medical examination and conducts various tests.


Laboratory Tests
One key test is an examination of a patient's blood for alkaline phosphatase, an enzyme that can be found at particularly high levels in the blood when bone-forming cells are very active. This kind of high activity occurs normally when a young child's bones are growing, or when a broken bone is mending. Otherwise, it might be an indication that a tumor is creating abnormal bone tissue. Since alkaline phosphatase may rise in response to other causes, high levels don't necessarily indicate whether a patient has bone cancer, but they do signal the need for further evaluation.


Imaging Tests
A physician will usually order imaging tests such as an x-ray, which will allow the doctor to see any unusual bone growths. This may be followed by a bone scan, to see if there are other abnormal areas in the skeleton. Before a bone scan, a small amount of "tracer" material is injected into a vein. After a few hours, this tracer material, which is slightly radioactive, collects in places where there is new bone growth. A CT (computed tomography) or MRI (magnetic resonance imaging) scan is often ordered to show the exact size and shape of the suspected bone tumor, and to determine if it has invaded surrounding tissue or the bone marrow space.

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