Radiation therapy for childhood Hodgkin lymphoma

Radiation therapy uses high-energy rays or particles to destroy cancer cells. It may be used to treat childhood Hodgkin lymphoma (HL). The healthcare team will consider your child’s needs to plan the type and amount of radiation, and when and how it is given.

Children with HL may be given radiation therapy after chemotherapy. Childhood HL is treated with external radiation therapy.

During external radiation therapy (also called external beam radiation therapy), a machine directs radiation through the skin to the tumour and some of the tissue around it. For childhood HL, radiation is given to only to the lymph nodes known to have cancer. This is called involved-nodal radiation therapy (INRT). It gives radiation to the smallest area possible, which can help lower the risk of late effects. Doctors will sometimes give an extra dose of radiation to bulky tumours.

Radiation therapy is usually given Monday to Friday. For a few minutes each day, radiation is directed at lymph nodes that have cancer. Radiation therapy usually lasts 2 to 4 weeks.

External beam radiation therapy may also be given to the entire body in preparation for a stem cell transplant. This is called total body irradiation, or TBI.

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) involves 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. It is useful for treating tumours in hard-to-reach areas.

Conformal proton beam radiation therapy is a new way of giving radiation. It isn’t available in many treatment centres. Children requiring this treatment may 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 release energy only after travelling a certain distance. As a result, protons cause less damage to tissues that 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 tumours in hard-to-reach areas.

Side effects can happen with any type of treatment for childhood HL, but every child’s experience is different. Some children have many side effects. Other children have only a few side effects.

During radiation therapy, the healthcare team protects healthy cells in the treatment area as much as possible. But damage to these 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. Sometimes late side effects develop months or years 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, the treatment schedule and the child’s age. Some common early side effects of radiation therapy used for childhood HL are:

• skin problems
• fatigue
• sore mouth and throat
• taste changes
• difficulty swallowing
• heartburn
• hoarseness
• nausea and vomiting
• diarrhea
• bone marrow suppression

These side effects will usually go away over time and are managed differently depending on the symptom.

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

Tell your child’s healthcare team if your child has these side effects or others 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.

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