Radiation therapy uses high-energy radiation to kill cancer cells. In people with Ewing tumors, radiation therapy may be used with surgery, or it may be used instead of surgery, especially if it would be hard to remove the entire tumor surgically. In either case, chemotherapy is usually given before, during, and afterward.

External beam radiation therapy focuses high-energy beams on the cancer from a machine outside the body. This is the type of radiation therapy most often used to treat Ewing tumors.

Before treatments start, the radiation team takes careful measurements to determine the correct angles for aiming the radiation beams and the proper dose of radiation. External radiation therapy is much like getting an x-ray, but the radiation is more intense. The procedure itself is painless. Each treatment lasts only a few minutes, although the setup time -- getting your child into place for treatment -- usually takes longer. Most often, radiation treatments are given 5 days a week for several weeks.

Some newer external radiation techniques allow doctors to focus the radiation more precisely.

Three-dimensional conformal radiation therapy (3D-CRT): Three-dimensional-CRT uses the results of imaging tests such as MRI and special computers to precisely map the location of the tumor. Several radiation beams are then shaped and aimed at the tumor from different directions. Each beam alone is fairly weak, which makes it less likely to damage normal tissues, but the beams converge at the tumor to give a higher dose of radiation there. Your child may be fitted with a plastic mold resembling a body cast to keep him or her in the same position so that the radiation can be aimed more accurately.

Intensity modulated radiation therapy (IMRT): IMRT is an advanced form of 3D therapy that may be especially useful for tumors near the spine. In addition to shaping the beams and aiming them at the tumor from several angles, the intensity (strength) of the beams can be adjusted to limit the dose reaching the most sensitive normal tissues. This may let doctor deliver a higher dose to the tumor. Many major hospitals and cancer centers are now able to provide IMRT.

Possible side effects of radiation therapy

Because of the possible side effects of radiation therapy (especially in growing children), surgery is often preferred if it is possible. But improvements in the way radiation is given now allow children with Ewing tumors to be treated with less radiation than was used in the past, helping to reduce some of these side effects.

The side effects of radiation therapy depend on the dose of radiation and where it is aimed.

Effects on skin areas that receive radiation can range from mild sunburn-like changes to more severe skin reactions. Radiation to the abdomen or pelvis can cause nausea, diarrhea, and urinary problems. In some cases there may be significant long-term damage to the bladder or bowel.

A serious problem of radiation therapy in children is that it can interfere with bone growth. In younger children, some bones will not grow well after radiation. For example, one leg may be much shorter than the other. Radiotherapy of facial bones may cause uneven growth, and some disfigurement may result. If a child is fully or almost fully grown, however, the side effects of radiation therapy will not be as severe.

Another major concern with radiation therapy is that it may cause a new cancer to form in the part of the body that was treated with the radiation. This is most often a different type of bone cancer called osteosarcoma. The higher the dose of radiation, the more likely this is to occur. This small risk should not keep children who need radiation from getting treatment. Still, it's important to continue follow-up visits with your child's doctor so that if problems come up they can be found and treated as early as possible.

Side effects of radiation therapy to the spinal cord or brain may include nerve damage, headaches, and trouble thinking, which usually become most serious 1 or 2 years after treatment. Fortunately, Ewing tumors rarely spread to the brain, but they can extend into the brain from nearby bones of the skull.

For more detailed information on radiation therapy, see the separate American Cancer Society document, Understanding Radiation Therapy: A Guide for Patients and Families.

Last Medical Review: 08/20/2009
Last Revised: 08/20/2009