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Ewing's sarcoma is a cancerous (malignant) tumor that usually begins growing in a bone. It occurs primarily in children and young adults, often appearing during the teen years.
Although Ewing's sarcoma can develop in any bone, it usually affects the long bones, such as the thighbone (femur), shinbone (tibia), and upper arm bone (humerus). The bones of the pelvis are also often affected. Occasionally, the tumor begins in the muscles and soft tissues (this is called extraosseous Ewing's sarcoma).
Ewing's sarcoma can spread (metastasize) to other parts of the body, such as the lungs, bone marrow, and other soft tissues.
When compared with other cancers, malignant bone tumors like Ewing's sarcoma are rare. Of these rare tumors, Ewing's sarcoma is the second most common in children and young adults. According to data on children younger than 15 years old, approximately 1.7 children out of a million develop the disease.
Recently, doctors have defined the disease to include four types of cancer, referred to as the Ewing's Family of Tumor (EFT). This includes the Ewing's sarcoma of bone, the Ewing's sarcoma of soft tissue, primitive neuroectodermal tumor (PNET) which may occur in both bone and soft tissue, and Askin's tumor, a PNET that occurs in the bones of the chest.
This article focuses on Ewing's sarcoma of bone.
There is no known cause of Ewing's sarcoma.
Most cancers are known to arise from a certain kind of tissue or organ. For example, breast cancer arises from breast cells. In the case of Ewing's sarcoma, however, doctors do not know the exact type of cell where the cancer starts.
What is known is that the cancer forms when changes occur in a cell's chromosomes. In Ewing's sarcoma cells, the genetic material in chromosomes #11 and #22 is mismatched. This genetic abnormality is not inherited from a child's parents - the chromosomal changes occur after a child is born.
It is not understood why this abnormality occurs. Doctors have not identified any risk factors that make one child more susceptible than another. The tumor does not develop as a result of any dietary, social, or behavioral habits. There are no known ways to prevent the disease, and parents should know that there is nothing they could have done differently to prevent their child's tumor.
There is usually pain and possibly swelling at the site of the tumor. But, the tumor may be present for many months before it becomes large enough to cause pain and swelling.
Although injuries are not a known cause, an injury may draw attention to a tumor. For example, a bone weakened by a tumor may break after a minor injury.
After discussing symptoms and conducting a physical examination, your doctor will use several types of tests to diagnose Ewing's sarcoma.
First, a doctor uses imaging studies to create detailed pictures of the affected area. These include x-rays, magnetic resonance imaging (MRI) scans, computed tomography (CT) scans, and bone scans.
To confirm that the tumor seen in imaging studies is Ewing's sarcoma, your doctor will do a biopsy. This involves taking a piece of tissue from the tumor and looking at it under a microscope. A biopsy is a simple procedure that may be done in an operating room or x-ray department.
Ewing's sarcoma tumors are sometimes called small blue cell (round cell) tumors because of the way they look under a microscope.
Once the tumor is identified as Ewing's sarcoma, your doctor will conduct more tests to determine whether the cancer has spread. This process is known as "staging." These additional tests may include:
- Blood tests
- CT scan of the lungs
- Bone scan
- Bone marrow biopsy
The part of the body where the first tumor develops is called the "primary" site. Any parts of the body where it has spread are called "metastatic" sites.
By identifying the stage of the tumor, your doctor can determine the most effective treatment strategy.
At the time of diagnosis, many cases of Ewing's sarcoma have not spread to other parts of the body. Even if tests do not show spread, however, doctors will plan a treatment strategy that assumes a very small amount of spread (micrometastatic disease) has already happened.
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.
The main treatments are chemotherapy, surgery, and radiation. These treatments are often used in some combination with each other.
Both surgery and radiation are effective treatments for removing the primary tumor. In most cases, doctors use surgery to remove the tumors when possible. Radiation treatment is used only when surgery cannot completely remove the tumor or would cause the patient to lose function in the affected area.
Most physicians work in teams to tailor their recommendations of surgery and/or radiation to a patient's specific situation.
Chemotherapy is a drug treatment used to kill the primary tumor and any spread of the cancer. It is often used initially to shrink the primary tumor and make it easier to remove with surgery.
Because chemotherapy treatment for Ewing's sarcoma lasts for a length of time, the drugs are given through an indwelling central venous catheter. This is a very thin tube that is inserted into a vein in the chest that will stay in place until the end of treatment. It is placed just before chemotherapy treatment is started.
Chemotherapy is done in cycles. It uses combinations of various drugs to destroy cancer cells. Because these drugs affect the entire system, healthy cells can also be damaged, including white blood cells and platelets. The rest period between cycles lets the blood cell count recover, but there are still side effects from the cell damage. The most common side effects include hair loss, nausea, mouth sores, and fevers. Certain medicines can help relieve some side effects.
Surgery and/or radiation to remove the primary tumor can be done either before or during chemotherapy. Most of the time, this occurs after several cycles of chemotherapy. After recovery from surgery and/or radiation therapy, chemotherapy will be resumed. It generally takes close to one year to finish all the cycles of chemotherapy.
Various medications are used in chemotherapy treatment for Ewing's sarcoma. The most common drugs are vincristine, dactinomycin, cyclophosphamide, and doxorubicin. Recent evidence shows the addition of ifosfamide and etoposide helps.
Many advances in chemotherapy have been made through knowledge gained by placing patients in clinical trials. Physicians request permission to enroll patients in specific clinical trials. Your doctor can tell you more about any clinical trials currently being held.
Surgery is used to remove the primary tumor and occasionally any smaller tumors, if the disease has spread. The tumor must be removed entirely to keep it from returning, and a margin of healthy muscle and joint tissue surrounding the tumor is also removed.
Surgeons can reconstruct the bone, joint, or soft tissue site. They may use bone grafts, artificial joints, or a combination of these. The goal is to restore the body part so that the patient can do their normal everyday activities.
The amount of function that can be restored from reconstructive surgery depends upon how much muscle and joint tissue can be preserved while still removing the entire tumor.
Depending on the site of surgery, the patient may need to limit putting weight on the reconstructed limb. Ongoing rehabilitation with physical therapy is necessary to return to daily activities. A physical therapist may provide exercises to help maintain range of motion and restore strength.
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.
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.
It is important to consider the risks and complications associated with the surgery. Infections, problems with the artificial joint, and wound healing are the most frequent concerns.
The main goal of tumor surgery is to remove the tumor entirely and keep it from returning; the reconstructive issues, while important, are nonetheless a secondary goal.
Some Ewing's sarcoma tumors cannot safely be removed with surgery. In these cases, doctors typically use radiation therapy to destroy the tumor. Occasionally, a tumor requires amputation of the limb to ensure that the tumor and surrounding tissues have been completely removed.
Radiation therapy can destroy cancer cells and shrink tumors. It is most often used to lower the chance of the primary tumor coming back (recurring). Radiation may also be used instead of surgery at sites where surgery is too risky or complicated. Occasionally, radiation therapy is used in conjunction with surgery.
When radiation treatment is used, daily treatments are given over the course of many weeks. While the discomfort of surgery may be avoided, there are risks associated with the radiation, including:
- Skin damage
- Muscle scarring and loss of joint flexibility
- Damage to nearby organs
- Loss of bone growth in growing children
- Secondary cancers caused by radiation
- Chronic swelling of an extremity
- Slow wound healing
Over the years, the outcome for patients with Ewing's sarcoma has improved considerably. This is thanks to improvements in chemotherapy, diagnostic imaging, and reconstructive techniques.
Prognosis varies from patient to patient, but in general, two thirds of patients without any spread of the disease will survive at least five years after diagnosis with standard treatment.
Several factors can affect the likelihood of survival. These include:
- No known spread of the cancer
- An excellent response to chemotherapy
- Primary tumors in the arms and legs instead of the pelvis
- Complete removal of the tumor
Survivors of Ewing's sarcoma require continued follow-up care to monitor any late side effects from treatment, and any reoccurrence of the tumor. When tumors come back, it usually happens within the first few years after treatment.
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 also 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.
The American Academy of Orthopaedic Surgeons
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