What is Osteosarcoma?

Osteosarcoma is a malignant tumor that grows inside bones. It is often thought of as a childhood cancer because 65% of all cases occur in adolescents between the ages of 14 and 16. Osteosarcoma is a serious form of cancer, and though treatment has improved, the survival rate is still alarmingly low.

In roughly 80% of the cases, osteosarcomas grow in and around the knee. The tumors are made up of the same tissue as bone, but are much weaker. Early detection is rare, though some evidence of a connection between certain forms of eye cancer in children, called retinoblastoma, and osteosarcoma has been established. If the patient has had retinoblastoma, any symptoms that might indicate osteosarcoma, for example pain in the leg that worsens at night, should be screened early to detect the presence of bone tumors.

In many cases, however, there is no known cause for an osteosarcoma. Symptoms, generally mild at first, like leg pains, are quite common in all children. Should leg pain develop into limping, or if the area around the leg seems swollen, not as the result of a direct injury, medical advice should be sought. Early detection through x-ray, magnetic resonance imaging (MRI), and computed tomography (CT) scans; along with biopsy of any tumors found, significantly improves survival rate. Unfortunately, no test exists to screen patients at onset because generally symptoms at onset are mild.

The earlier the detection of this cancer, the less chance the cancer has to metastasize and form tumors in the lungs or in other bones. Osteosarcoma, once diagnosed, is classified in stages. A localized osteosarcoma has not spread and is affecting only the bones and muscles it touches. Metastatic osteosarcoma has spread to other parts of the body. In over 75% of of metastatic osteosarcoma cases, tumors develop in the lungs.

Numbers can also be assigned to stages. For example, stage one osteosarcoma is a small, non-metastasized tumor. Stage two is a larger tumor that has not yet metastasized. Stage three means the tumor has spread to other types of the bone, and stage four means the cancer has spread to the lungs. Survival at stage four depends upon whether tumors in the lungs can be surgically removed.

Treatment of osteosarcoma depends on stages. If a single stage one or stage two sarcoma is detected, a doctor of oncology will prescribe chemotherapy as the first step in an effort to shrink the existing tumor and hopefully prevent metastasis. If the tumor shrinks, an orthopedic surgeon then removes it. In some cases, the only successful means of removal is through amputation of the limb.

There are .3 cases of osteosarcoma per 100,000 people. Of those affected, one third will die in the first year. Those least at risk will present with stage one or stage two sarcomas. Therefore, anyone who notices symptoms such as those listed above should seek his or her physician's advice. Parents should be particularly vigilant of such symptoms in their adolescent children.