Diagnosis & staging
Diagnosis
These are tests that may be used to diagnose this type of cancer.
- Physical examination.
- An x-ray to help locate the tumour.
- A chest x-ray is used to determine if the cancer has spread to the lungs.
- A computerized tomography scan (CT Scan) produces a three dimensional image of the tumour and also screens for spread to the lungs if the chest X-ray was normal.
- A magnetic resonance imaging scan (MRI) produces detailed images of the tumour.
- A biopsy requires the removal of a small amount of tissue for examination under a microscope to determine if the tumour is cancerous. This step in the diagnosis should be approached with caution, and should be done in consultation with an orthopedic oncologist.
- A routine bone scan is done for patients with osteosarcoma or Ewing's sarcoma at diagnosis, at completion of their therapy and at recurrence.
For more information on tests used to diagnose cancer, see our Recommended Websites, Diagnostic Tests section.
Types and Stages
Types of Bone Sarcomas
- These tumours are named for the tissue type which they most resemble. For example, tumours that resemble bone-producing cells are called osteosarcoma; those looking like fat cells are called liposarcoma.
Osteosarcoma
- Osteosarcoma is the most common bone sarcoma.
- It occurs most often in the growing ends of the long bones of the arms and legs (such as at the knees and shoulders).
- Osteosarcoma is most commonly found in adolescents. It is slightly more common in males than in females and may be related to the adolescent growth spurt.
- Osteosarcoma also affects older adults.
- Osteosarcoma can spread to the lungs and to other parts of the body through the bloodstream.
- Lymph node involvement is unusual.
- Surgery to remove the tumour completely is the primary method of treatment. If possible, the part of the bone that has been removed will be reconstructed to avoid amputation.
- Chemotherapy is used to stop the cancer from spreading to the lung and other organs in the body.
- Radiation therapy is rarely used.
Chondrosarcoma
- Chondrosarcoma is a type of bone tumour that grows in the cells that produce cartilage.
- It occurs most often in older adults.
- Bone swelling and pain are the most common symptoms.
Ewing's Sarcoma
- Ewing's sarcoma is a family of tumours that occur in the bone or soft tissue.
- Ewing tumour of the bone is a specific type of Ewing's sarcoma.
- Ewing's sarcoma is a very aggressive type of bone sarcoma.
- Chemotherapy is used to stop the cancer from spreading to other organs in the body.
The following bone sarcomas are less common:
Chordoma
- This is a rare tumour arising at the end of the spinal cord or near the base of the skull.
- Pain near the end of the spinal cord is most typical for tumours in that area.
- Tumours growing at the base of the skull produce symptoms that affect the cranial nerves, most commonly the nerves of the eyes.
- Symptoms may last for many months before the diagnosis is clear.
- Tumours grow very slowly and spread by local invasion.
- Chordomas are generally treated by surgery and radiation.
Malignant Fibrous Histiocytoma (MFH) of the Bone
- Malignant Fibrous Histiocytoma (MFH) is a rare malignant tumour of the bone.
- In some situations, MFH arises out of osteosarcoma.
- Osteosarcoma and Malignant Fibrous Histiocytoma are generally treated in the same way.
Peripheral Neuroectodermal Tumour (PNET)
- Peripheral Neuroectodermal Tumours (PNET) are more common in childhood.
- The tumours have the same genetic change as Ewing's sarcoma of the bone.
Myeloma, Lymphoma
- Myelomas and lymphomas are cancers of the bone marrow, which are discussed in their own sections. See the Types of Cancer pages on Myelomas and Lymphomas.
Stages
Staging describes the extent of a cancer. The TNM classification system is used as the standard around the world. In general a lower number in each category means a better prognosis. The stage of the cancer is used to plan the treatment.
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G describes how the tumour cells look under the microscope
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T describes the site and size of the main tumour (primary)
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N describes involvement of lymph nodes
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M relates to whether the cancer has spread (presence or absence of distant metastases)
Stage I The tumour is low grade (the tumour looks more like normal bone). The tumour is any size. It has not spread to lymph nodes or distant sites. The cancer does not look different from normal tissue. Stage II The tumour is high grade (the tumour looks very different from normal tissue.). The tumour is any size. The cancer has not spread to lymph nodes or distant sites. Stage III The tumour is high grade and has spread to one or more sites within the bone. Stage IV The cancer has spread to lymph nodes or to distant sites.
- G1 Low grade
- G2 Intermediate grade – treated as high grade
- G3 High grade
- T1 Tumour is 8cm or less in greatest dimension
- T2 Tumour more than 8cm in greatest dimension
- T3 Discontinuous tumours in the primary bone site
- NX Regional lymph nodes cannot be assessed
- N0 No regional lymph node metastasis
- N1 Regional lymph node metastasis
- M0 No distant metastasis
- M1 Distant metastasis
- M1a Lung
- M1b Other distant sites
