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Radiation therapy for childhood bone cancer
Radiation therapy uses high-energy rays or particles to destroy cancer cells. Radiation therapy is commonly used to treat childhood Ewing sarcoma. It is often used along with other treatments. It is rarely used to treat childhood osteosarcoma. The healthcare team will consider your child’s personal needs to plan the type and amount of radiation and when and how it is given. Your child may also receive other treatments.
Radiation therapy is given for different reasons. Your child may have radiation therapy:
- to shrink a tumour before surgery and make it easier to remove (called neoadjuvant therapy)
- to destroy cancer cells left behind after surgery or chemotherapy and reduce the risk that cancer will come back, or recur (called adjuvant therapy)
- as the main treatment, with chemotherapy, to destroy cancer cells
- to treat a recurrence
- to relieve pain or control the symptoms of advanced osteosarcoma (called palliative therapy)
Radiation may be offered as the main treatment instead of surgery if doctors can’t remove the tumour with surgery because the tumour is large or it is near or touching vital structures such as the spinal cord.
Types of radiation therapy
The following types of radiation therapy are most commonly used to treat childhood bone cancer.
External beam radiation therapy
During external beam radiation therapy, a machine directs radiation through the skin to the tumour and some of the tissue around it. The radiation therapy team will base the size of the treatment area on the size of the tumour or tumours as well as a margin of healthy tissue surrounding the tumour. Radiation therapy is usually given in small daily doses (called fractions) over a 4 to 5 week period.
Doctors may use the following types of external beam radiation therapy to accurately target the area to be treated and spare as much surrounding normal tissue as possible.
Intensity-modulated radiation therapy (IMRT) delivers radiation from many different angles to treat the entire tumour. In addition to shaping and aiming the radiation beams, IMRT allows the radiation oncologist to adjust the strength, or intensity, of the individual beams. This allows a higher dose to be delivered to the tumour and reduces the dose of radiation reaching nearby normal tissues. IMRT can be useful for treating bone tumours in hard-to-reach areas such as the spine or pelvis.
Conformal proton beam radiation therapy is a new way of giving radiation. It isn’t available in many treatment centres. Currently, there are no machines in Canada. Children requiring this treatment have to go to certain centres in the US. Conformal proton beam radiation therapy uses proton beams instead of x-ray beams. X-ray beams release energy before and after they hit their target. Protons only release energy after reaching a certain distance. As a result, protons cause less damage to tissues they pass through before reaching their target. Conformal proton beam radiation therapy causes the least amount of damage to nearby normal tissues. It is useful for treating bone tumours in hard-to-reach areas such as near the spinal cord or brain.
Stereotactic radiosurgery involves giving very high doses of radiation in a small number of sessions (fractions) to a precisely defined area of tumour involvement. Stereotactic radiosurgery may be used in some centres.
Side effects can happen with any type of treatment for childhood bone cancer, but every child’s experience is different. Some children have many side effects. Other children have few or none at all.
During radiation therapy, the healthcare team protects healthy cells in the treatment area as much as possible. But damage to healthy cells can happen and may cause side effects. Side effects can happen any time during, immediately after or a few days or weeks after radiation therapy. Most side effects go away on their own or can be treated, but some side effects may last a long time or become permanent.
Side effects of radiation therapy will depend mainly on the size of the area being treated, the specific area or organs being treated, the total dose of radiation, treatment schedule and the child’s age. Some common side effects of radiation therapy used for childhood bone cancer are:
- skin reactions
- hair loss
- bone marrow suppression
- nausea and vomiting
- loss of appetite
- radiation enteritis
Some side effects can develop months or years after radiation therapy for childhood bone cancer. Find out more about late effects of treatment for childhood bone cancer.
Tell the healthcare team if your child has any side effects you think might be from radiation therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help your child deal with them.