Radiation therapy for Wilms tumour

Radiation therapy uses high-energy rays or particles to destroy cancer cells.

Radiation therapy is sometimes used to treat Wilms tumour. The healthcare team will use what they know about the cancer and about your childʼs health to plan the type and amount of radiation and when and how it is given.

Radiation therapy may be used to:

• destroy cancer cells left behind after surgery and chemotherapy to reduce the risk that the cancer will come back (recur) (called adjuvant therapy)
• relieve pain or control the symptoms of recurrent Wilms tumour that is not responding to chemotherapy (called palliative therapy)

Radiation therapy is given for different reasons. It is sometimes used to treat Wilms tumour that is more advanced or has an anaplastic (unfavourable) histology. It may be given to the area where the kidney was removed with surgery or to the entire abdomen. It may also be given to the chest to treat Wilms tumour that has spread to the lungs.

The following types of radiation therapy are most commonly used to treat Wilms tumour.

During external radiation therapy, a machine directs radiation through the skin to the tumour and some of the tissue around it. External radiation therapy is also called external beam radiation therapy. The size of the area treated with radiation therapy depends on the size of the tumour and how much the cancer has spread. Very young children may be sedated before radiation therapy to keep them still during treatment.

Radiation therapy is given as soon as possible after surgery to remove the tumour (usually within 10 to 14 days).

Doctors may use the following external radiation techniques to accurately target the area to be treated and spare as much surrounding normal tissue as possible.

3D conformal radiation therapy (3D-CRT) has many beams of radiation directed at the tumour. The radiation oncologist uses a CT scan or an MRI to map the exact location and shape of the tumour. The radiation beams are then shaped and aimed at the tumour from different directions to treat the tumour from all angles. Each individual beam is fairly weak and less likely to damage normal tissue. A higher dose of radiation is delivered where the beams meet at the tumour.

Intensity-modulated radiation therapy (IMRT) is similar to 3D-CRT in that it 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 (intensity) of the individual beams. This reduces the dose of radiation reaching nearby normal tissue while allowing a higher dose to be delivered to the tumour and reducing side effects. Itʼs useful for treating tumours in hard-to-reach areas.

During radiation therapy, the healthcare team protects healthy cells in the treatment area as much as possible. 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, the treatment schedule and the childʼs age.

Tell the healthcare team if your child has any side effects that you think are from radiation therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help your child deal with them.

These are common side effects of radiation therapy to the abdomen for Wilms tumour:

• low blood cell counts
• fatigue
• skin problems
• nausea and vomiting
• loss of appetite
• diarrhea
• radiation enteritis
• kidney problems
• ulcers (open sores in the lining of the stomach or small intestine)

These are common side effects of radiation therapy to the chest for Wilms tumour:

• fatigue
• skin problems
• swallowing problems

Other side effects can develop months or years after treatment for Wilms tumour. Find out more about late effects of treatments for Wilms tumour.

Find out more about radiation therapy and side effects of radiation therapy. To make the decisions that are right for your child, ask the healthcare team questions about radiation therapy.