An osteosarcoma is a malignant tumor of bone that rapidly spreads to the lungs and, less commonly to other areas. Osteosarcoma occurs mainly in adolescents, when the body is developing rapidly, and in the elderly. In young people, osteosarcoma develops for no known reason, although at least one gene has been linked to increased risk; in elderly people, it is a late, rare complication of Paget's disease.
The most common site of the tumor in young people is in a long bone of the arm or leg, or around the knee, hip, or shoulder. The first visible symptom is usually a painful visible swelling of the affected bone (if it is near the surface) or a deep-seated pain (if the affected bone cannot be felt through the skin).
As a complication of Paget's disease, an osteosarcoma may develop in several bones; its pain may be indistinguishable from that caused by the original disease.
Diagnosis and treatment
Diagnosis is usually based on X-rays of the bone. Other bone imaging techniques, such as MRI, may also be used.
Osteosarcoma is sometimes treated by radiotherapy, but it is usually necessary to remove the affected bone surgically. In most cases, this means amputation of a limb; in some cases, a prosthesis can be fitted immediately after the amputation. Instead of amputation, it is sometimes possible to remove affected bone and replace it by a bone graft or by an artificial bone.
Treatment with anticancer drugs is usually given for several months after surgery to destroy any cancer cells that may have spread to other parts of the body. With this additional treatment, the outlook is good; about half of all patients whose disease is discovered early are cured.