Overview of Bone Tumors
Bone tumors may be cancerous (malignant) or noncancerous (benign).
Cancerous tumors may start in the bone (primary cancer) or start in other organs (such as the breast or prostate) and spread to the bone (metastatic cancer).
Tumors may cause unexplained, progressively worsening bone pain, swelling, or a tendency to fracture easily.
The diagnosis is sometimes based on the results of an imaging test (such as x-ray, computed tomography, or magnetic resonance imaging) but often requires removing a tissue sample of the tumor or bone for examination under a microscope (biopsy).
Bone tumors may be noncancerous or cancerous and primary or metastatic.
Primary bone tumors originally start in the bone. Primary bone tumors may be noncancerous or cancerous.
Metastatic bone tumors are cancers that spread to (metastasize) the bone from other areas in the body (for example, from the breast or prostate gland—see also Development and Spread of Cancer). Metastatic bone tumors are always cancerous.
In children, most bone tumors are primary and noncancerous. Some bone tumors (such as osteosarcoma and Ewing sarcoma) are primary and cancerous. Very few are metastatic (such as neuroblastoma and Wilms tumor).
In adults, most cancerous bone tumors are metastatic. Overall, noncancerous bone tumors are relatively common, but cancerous primary bone tumors are rare, occurring in only about 2,500 people yearly in the United States. This number does not include multiple myeloma, a cancer that develops in the marrow inside the bone rather than in the hard bone tissue that makes up the bone.
Although benign bone tumors do not metastasize, some types grow rapidly and destroy nearby tissues.
A personmay sometimes have a painless lump, which may eventually become painful, but often the first symptom of a bone tumor is bone pain. The pain can be severe. Pain may occur when at rest or at night and tends to progressively worsen. Sometimes a tumor, especially if it is cancerous, gradually weakens a bone. The weakness makes it much easier for the bone to break (fracture) while doing routine activities (this type of fracture is called a pathologic fracture).
When people have a joint or limb that is always painful, even when they are not using it, doctors typically do x-rays. X-rays can show doctors that the bone has an abnormal appearance or can show a growth or a hole in the bone. However, although doctors can see such abnormalities on x-rays, they usually cannot tell whether a tumor is noncancerous or cancerous. However, some tumors can be identified as noncancerous by an x-ray. For example, this identification is often possible with Paget disease of bone, enchondromas, bone cysts, nonossifying fibromas, and fibrous dysplasia.
If an x-ray does not give doctors enough information, computed tomography (CT) and magnetic resonance imaging (MRI) often help them determine the exact location and size of the tumor and give additional information about the nature of the tumor. However, these tests usually do not provide a specific diagnosis.
Doctors may do bone scans to identify the locations of many tumors at one time because bone scans show the entire skeleton.
Doctors may also do positron emission tomography (PET or PET scan) , usually as PET combined with CT scanning (PET-CT). PET and PET-CT are other types of imaging tests that can show where a cancer is, where it has spread, and how it is responding to treatment.
If cancer is a reasonable possibility, a biopsy is usually necessary for diagnosis. Three types of biopsies may be done depending on the tumor:
Many tumors can be biopsied.
In an aspiration biopsy, doctors insert a needle into the tumor and withdraw some cells. No incision is needed. However, because the needle used is very small, sometimes normal cells may be sampled and cancer cells are missed, even when cancer cells are lying right beside the normal cells.
A core biopsy is done with a larger needle and often done so that more cells can be withdrawn and examined. Because both aspiration and core biopsies are done by using needles, they are considered needle biopsies.
An open biopsy (also called an incisional biopsy) is a surgical procedure. Sometimes an open biopsy is done when more tissue is needed for the doctor to make an adequate diagnosis. In this procedure, a surgeon cuts through the skin and into the deeper tissues to obtain an adequate sample for diagnosis. This procedure can sometimes be done at the same time that surgery is done to treat the tumor. If the entire tumor is removed, the procedure is called an excisional biopsy.