Definition and incidence
Though rare, it is the most common type of primary bone cancer (marrow cancers are more common), and occurs mainly in adolescents and young adults. The most common site is around the knee, but any bone may be affected. Some cases occur in older persons, associated with Paget’s disease, or irradiation.
Causes and risk factors
There is no known definite cause, though there is a tendency for this cancer to run in families, and a genetic link has been suggested. There are no known predisposing risk factors.
The patient usually sees a doctor because of
- Tenderness to touch
- Swelling of the bone
- Limitation of movement
- An unexpected fracture in an otherwise healthy young person
The external appearance of the affected area is not diagnostic, so special investigations must be done.
An X-ray of the affected area is mandatory, as valuable time may be lost with a wrong diagnosis and inappropriate treatment. X-ray appearance suggesting osteosarcoma is followed by scans, either CT, PET or MRI; and may proceed to a biopsy done by an experienced orthopaedic surgeon to determine cell type. This decision is made by a panel (see Management).
The site, size and spread of the tumour will affect the choice of treatment, and the likely outcome.
Osteosarcoma is jointly managed by experienced clinical and orthopaedic oncologists.
Chemotherapy may be used to shrink the tumour, and deal with any spread to distant sites (metastases), such as to the lungs. This then may permit limb-sparing surgery, and avoid amputation. Reconstructive surgery may be considered in the hands of an experienced orthopaedic surgeon, and may involve repeated surgery for prostheses and tendon re-implantation.
In some cases after chemotherapy, limb-sparing surgery may not be possible. In others, whilst some form of surgery might be possible, it may be too debilitating. In these cases (where limb-sparing surgery is not possible) an amputation is indicated. It is important to note that all patients with Osteosarcoma should get four cycles of chemotherapy which can either be given pre-surgery or post-surgery. Primary radiation for Osteosarcoma should be reserved for anatomical areas where surgery is not possible, e.g. spinal lesions. It is also important to note that biopsies should preferably be done by the Orthopaedic surgeon, since the whole biopsy tract should be removed at definitive surgery, and a badly placed biopsy tract could compromise good surgery.
Complications of the disease, and side effects of treatment, such as wound infection, pain and nausea, will also need managing.
This will depend largely on the stage of the disease when it is first diagnosed, the skills and experience of the medical team involved, and the adequacy of the treatment regime chosen.
- On average, early limited disease, well treated, can have a more than 90 percent five-year survival rate.
- For large aggressive tumours with early multiple metastases, this may drop to 50 percent.
No definite prognosis can be given, as each patient responds differently to treatment.
Reviewed by Dr Michiel C Botha, MBChB Pretoria, MMed (Rad.Onc.) University of Free State, Senior Specialist in the Dept of Oncotherapy, Universitas Hospital Bloemfontein, 8 April 2010