Ewing's sarcoma is a very rare cancer that appears as a solid tumor, most often in adolescents and children. Sixty-four percent of cases occur between ages 10 and 20, and 27% occur before age 10. Only 9% of people with Ewing's sarcoma are adults, usually between the ages of 20 and 30. About 150 new cases are reported per year in the United States. About 96% of people with this cancer are white.

Because Ewing's sarcoma typically develops within bones, it used to be considered a bone cancer. It actually arises from a type of primitive nerve cell. For this reason, Ewing's sarcoma can occur outside of the bones, in the body's soft tissues.

A similar tumor, called primitive neuroectodermal tumor (PNET) or peripheral neuroepithelioma, was once described as a separate cancer from Ewing's sarcoma. Now they are thought to represent different types of the same cancer. Their treatment and response to therapy are similar. (Askin's tumor is the name given to PNET tumors of the chest wall.) PNET may also occur in the testes and can be confused with a testicular germ cell cancer. Specialized laboratory studies are done to determine the nature of the abnormal cell, since the treatment for PNET differs from that of a typical testicular cancer.

Ewing's sarcoma usually develops in the arms or legs, but sometimes occurs in the pelvis, ribs, spine and, in rare cases, other bones or soft tissues. At the time of diagnosis, about 23% to 26% of Ewing's sarcomas have spread (metastasized) to another site, usually the lungs, a second bone or the bone marrow.

Like other cancers, Ewing's sarcoma is made of abnormal cells that multiply out of control. The cells of Ewing's sarcoma show a changed pattern in the chemical material you inherited from your parents (DNA). This change, called a translocation, usually involves a rearrangement of DNA between chromosome 22 and chromosome 11. The problem, however, is not inherited. It develops after birth. There is no evidence that this cancer is related to exposure to radiation, chemicals or any other environmental factors. The cause remains a mystery.

Symptoms of Ewing's sarcoma include:

• Persistent pain and swelling in an arm or leg, which may occur at rest and may even awaken the person from sleep
• A firm lump on an arm or leg, sometimes with tenderness
• A limp, if the tumor affects the leg
• Difficulty breathing, if the tumor affects the ribs
• Fever (in 28% of people)
• Weight loss

In physically active or competitive children, the pain and swelling of Ewing's sarcoma can be mistaken for symptoms of a sports injury. In those who have a fever, symptoms of Ewing's sarcoma often are confused with those of a bone infection called osteomyelitis.

After reviewing your symptoms, your doctor will examine you, paying special attention to the painful, swollen area. Your doctor will check the area for warmth, redness, swelling, tenderness, limited motion and any signs that a joint is involved. An X-ray of the area, as well as tests of your blood and urine, usually follows the physical exam. In most cases, the results of laboratory tests are fairly normal because no specific blood or urine tests can confirm the diagnosis of Ewing's sarcoma. However, the X-ray usually will show either the typical pattern of a Ewing's sarcoma affecting a bone or some other abnormality, usually an area of bone destruction, which indicates the presence of a bone tumor.

Once your doctor finds X-ray evidence of a bone tumor, he or she will refer you to a hospital that has the facilities, personnel and experience to treat bone cancer. There you will have further tests, such as magnetic resonance imaging (MRI) scans of the area to determine how far the tumor has invaded local structures. Once the location of the tumor is firmly established, you will have a biopsy of the tumor to confirm the diagnosis of Ewing's sarcoma. In a biopsy, a small amount of tissue is removed and examined in a laboratory. You probably will have a chest X-ray and a radionuclide bone scan. A bone-marrow biopsy can check to see if the cancer has spread (metastasized) to your lungs, other bones or your bone marrow.

Once it develops, Ewing's sarcoma will continue to grow until it is treated. If not treated, this cancer can spread to the lungs and to other bones.

There is no way to prevent Ewing's sarcoma.

In most cases, Ewing's sarcoma is treated using chemotherapy, radiation therapy and/or surgery.

To stop the tumor from growing or spreading, doctors can remove it surgically or treat it with radiation. Usually, surgery can remove the cancerous tumor without amputating the limb. After removing the cancer, the surgeon fills in the area with a bone graft or artifical material (prosthesis) to allow the limb to remain as functional as possible. If the cancer has spread to the lungs, surgeons use open chest surgery (thoracotomy). Radiation therapy is also highly effective in treating Ewing's sarcoma. Which treatment is used depends on the size of the tumor and on how much of the surrounding tissues it had invaded.

Almost always, chemotherapy is used in addition to radiation and/or surgery to treat Ewing's sarcoma. Sometimes chemotherapy is given before surgery to make it easier to remove the tumor. Chemotherapy drugs also decrease the chance that the tumor will spread or grow in other areas of the body, such as the lungs or bone marrow.

If treatment is successful, you will be monitored closely through many years of follow-up visits. This is because Ewing's sarcoma can return as late as 10 years after the initial diagnosis. Also, a second cancer may develop in the area where you received radiation treatment. You also may suffer late side effects from the chemotherapy drugs.

Call your doctor if you or anyone in your family develops an area of persistent or unexplained pain and swelling in a bone, whether you have a fever or not.

After proper treatment, 50% to 60% or more of people whose cancer has not spread survive at least 5 years. This percentage increases to 80% if the tumor is located below the elbow or below the mid calf. People whose cancer has spread usually have a poorer prognosis, with a 5-year survival rate of approximately 25%.

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