BACKGROUND: Ewing’s sarcoma is a rare cancer that affects the bone or soft tissue. It is more common in males and usually affects children and young adults. About 250 children and adolescents are diagnosed with the disease every year in the United States, accounting for about 2 to 3 percent of childhood cancers. Ewing’s sarcoma most commonly occurs in the pelvis, femur, humerus and ribs. The cancerous cells can also metastasize to other parts of the body, including the bone marrow, lungs, heart, adrenal gland and other soft tissues. Symptoms of the disease vary from person to person and depend on the location and size of the cancer. Most often patients experience pain, swelling and tenderness. If the tumor is located near nerves, pain can be intensified. Swelling occurs especially when cancer is in the long bones of the arms or legs. Other symptoms include tiredness, fever, weight loss and anemia.
More than 90 percent of Ewing’s sarcoma cases are due to changes in genetic makeup, particularly a chromosome rearrangement between chromosomes #11 and #22. Some doctors classify the disease as a primitive neuroectodermal tumor (PNET), meaning it may have started in fetal tissue that developed into nerve tissue.
DIAGNOSIS AND TREATMENT: Diagnosis of Ewing’s sarcoma involves a complete exam, including blood tests, X-rays and other scans, biopsy of the tumor, and bone marrow aspiration/biopsy. The cancer is usually treated with chemotherapy to kill cancer cells that may be circulating around the body, surgery to remove the tumor, and/or radiotherapy to kill the cancer cells locally. With the advancement of limb-salvage surgery and the increased awareness of problems associated with radiotherapy, surgery has become the most often used local therapy. Radiotherapy is typically used now on tumors that are hard to reach surgically or that are in locations linked to surgical complications (spine, pelvis and skull). Radiotherapy is also sometimes given in combination with surgery.
The type of surgery a patient has depends on the size and location of their tumor and whether it has spread. It is sometimes necessary to remove all or part of a limb, but in most cases, limb-salvage surgery can be performed. In this surgery, all of the bone and cartilage affected by the tumor iss removed, leaving tendons, nerves and vessels intact. The bone is replaced with a bone graft or metal prosthesis. This surgery requires intensive rehabilitation and could take as long as a year before the patient regains full use of their limb. For pediatric patients, an expandable prosthesis is typically placed to help them reach their growth potential. The first expandable prosthetics used required multiple surgeries to lengthen them. Since that time, prosthetics have been developed that require a smaller procedure where an incision is made and a screwdriver turns a mechanical device to lengthen it.
MAGNETS GROWING BONE: George Douglas Letson, M.D., a surgical oncologist at Moffitt Cancer Center in Tampa, Fla., is working on an even more advanced procedure that involves lengthening prosthetics with no incision at all. The prosthetic used in this procedure has a telescoping, extending mechanism connected to a magnet. When the limb is placed inside a coil that has a rotating magnetic field, it turns the prosthetic, lengthening it at a rate of about 1 millimeter every four minutes.
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