Ewing's sarcoma is a cancerous (malignant) tumor. It usually begins growing initially in a bone. Occasionally, it also begins in the soft tissues (extraosseous Ewing's sarcoma). Unlike most cancers that are known to arise from a certain kind of tissue or organ. For example, osteosarcoma arises from bone cells and breast carcinoma arises from breast cells. Doctors don't know the exact cell of origin for Ewing's sarcoma.

Recently, doctors have defined the disease to include a family of tumors. This includes the Ewing's sarcoma of bone or soft tissue, and primitive neuroectodermal tumor (PNET). Sometimes these tumors are called small blue cell (round cell) tumors. They are named for the way they look under a microscope.

Compared with other cancers, all malignant bone tumors are rare. Among malignant bone tumors in children and young adults, Ewing's sarcoma is the second most common. It occurs in 1.7 per million to 2.7 per million children who are younger than 15 years old. There is no known cause.

There are no known risk factors for developing Ewing's sarcoma. There is no known genetic link. There is no means of prevention either. The tumor does not develop as a result of any dietary, social, or behavioral habits. Parents of affected children should know that there is nothing they could have done to prevent the tumor.

X-ray of a thighbone (femur) with Ewing's sarcoma.

Ewing's sarcoma usually affects the long bones, such as the thighbone (femur), shinbone (tibia), and upper arm bone (humerus). The bones of the pelvis may also be affected.

First, a doctor uses imaging studies to diagnose a bone tumor. These include X-rays, MRI (magnetic resonance imaging), CT (computed tomography), and bone scans.

The doctor confirms the diagnosis by taking a piece of tissue to look at under a microscope (biopsy). This may be done in an operating room or X-ray department.

Special tests can help the doctor diagnose Ewing's sarcoma. The hallmark is an abnormality in the cell's chromosomes. Genetic material is mismatched. Chromosomes #11 and #22 are affected.

More tests (blood tests, lung CT scan, bone scan, and bone marrow biopsy) are needed to show the extent of disease. This process is known as "staging."

Tests can show if cancer has spread to other sites. such as the lungs or bone marrow. The part of the body where the first tumor develops is called the "primary" site. Any parts of the body where it spreads are called "metastatic" sites.

Doctors in many specialties help treat Ewing's sarcoma. These include orthopaedic surgical oncologists, pediatric or adult medical oncologists, radiation oncologists, pathologists, and radiologists. Most patients are treated at major hospital institutions or cancer centers.

Ewing's sarcoma is usually diagnosed as a primary bone tumor without evidence of spread elsewhere. Even if tests to do not show spread, the treatment strategy assumes that a very small amount of spread (micrometastatic disease) has already happened.

The main treatments are chemotherapy, surgery, and radiation. Both surgery and radiation are effective treatments for the primary tumor. Many surgeons remove the tumor when doing so will not cause a major loss of function of the body part involved. Many doctors use radiation treatment only when a tumor cannot be removed completely or without the patient losing function.

Recently, more doctors are using surgery to remove the tumors when possible. Most physicians work in teams to tailor their recommendations of surgery and/or radiation to a patient's specific situation.

Chemotherapy

MRI scan of femur with Ewing's sarcoma before (left) and after (right) chemotherapy treatment. The size of the tumor is much smaller after chemotherapy.

Chemotherapy is used to kill the primary tumor and any unknown microscopic spread.

Chemotherapy uses multiple medications. The most common agents are vincristine (Oncovin®), dactinomycin (Actinomycin D®), cyclophosphamide (Cytoxan®), and doxorubicin (Adriamycin®). Recent evidence shows the addition of ifosfamide (Ifex®) and etoposide (VePesid®, VP-16) helps.

Chemotherapy is given through an indwelling central venous catheter. This is placed just before treatment is started.

Chemotherapy is done in cycles. It uses combinations of the various drugs. The time between cycles lets the blood cell count recover. This includes white blood cells and platelets. The drugs depress them. The patient will lose their hair. Various medications can lessen other side effects, such as nausea, mouth sores and fevers.

It generally takes close to one year to finish all the cycles of chemotherapy, with surgery and/or radiation. A doctor will look at the effect of chemotherapy. He or she will evaluate the number of cells killed in the tumor after it has been removed. This happens following several cycles of chemotherapy that may shrink the tumor. Many advances in chemotherapy have been made through knowledge gained by placing patients in clinical trials. Your doctor can tell you more. A physician may request permission to enroll a patient in a specific clinical trial.

Surgery

Surgery is used to remove the primary tumor and occasionally metastatic lesions. If necessary, surgery can also rebuild the limb or body part.

X-ray of same femur taken 14 years after surgical excision of Ewing's sarcoma and reconstruction using a cadaver bone graft with artificial joint replacement.

The surgeon can reconstruct the bone, joint, or soft tissue site. He or she may use bone grafts, artificial joints, or a combination (see Figure right). The goal is to restore the body part so the patient can do their normal everyday activities. Strenuous or athletic activities are likely to cause too much stress or wear on the reconstruction, but occasionally some patients will still attempt to perform these activities. Most patients, however, will not be able to do such activities due to the amount of muscle and joint tissue removed. The ability to restore function depends mainly upon how much muscle and joint tissue can be preserved while still removing the entire tumor safely in a manner to avoid the likelihood of it re-growing (local recurrence). The main goal of a tumor surgery is to remove the tumor entirely and keep it from returning; the reconstructive issues, while important, are nonetheless secondary goal.

Some patients may need more operations to keep the limb functioning for the rest of their lives. Reconstruction of a bone in a growing child is a special challenge. As the child grows, multiple procedures are needed to lengthen the reconstructed bone. Surgery and/or radiation can be done either before or during chemotherapy. Most of the time, the chemotherapy sessions will be stopped sometime during the first half of the treatments to complete the surgery/radiation. Chemotherapy is restarted once the wound site has healed enough, usually about 2 weeks to 3 weeks after surgery.

Depending on the site involved, the patient may need to limit weight bearing on the limb. Ongoing rehabilitation with physical therapy is needed to optimize function.

In many cases, doctors can avoid amputation by surgically removing the primary tumor. Rebuilding the bone and joints is then needed. It is important to consider the risks and complications associated with the surgery. Infections and problems with prosthesis and wound healing are the most frequent concerns.

The outcome for patients with Ewing's sarcoma has improved considerably. This is thanks to improvements in chemotherapy, diagnostic imaging, and reconstructive techniques.

In general, two thirds of patients without any demonstrable spread will survive at least five years after diagnosis with standard treatment. When tumors come back, it usually happens within the first few years after treatment.

The absence of known spread is the most important factor in favor of being more likely to survive. Other factors include having excellent response to chemotherapy, primary tumors in the extremities instead of pelvis, and complete removal of the tumor.

Treatment for Ewing's sarcoma will change in the years to come as new knowledge becomes available. Current research on the Ewing's family of tumors has focused upon many areas.

The meaning of the chromosomal abnormality is not known, nor is it known how this affects normal cellular function. Basic knowledge in this area could someday lead to newer therapies that may take advantage of the abnormalities in cellular function. It may target the cancerous cells.

Other investigations involve chemotherapy and address issues about proper drug dosage and the best combinations of drugs. Doctors are looking at various types of bone marrow transplants.

Biomechanical engineers and surgeons are always making improvements to artificial joints. Expandable prostheses, which can be lengthened as a child grows, are now available.

Doctors are researching tissue growth factors. They might help heal broken bones.