Radiation therapy for Hodgkin lymphoma

Radiation therapy uses high-energy rays or particles to destroy cancer cells. It may be used to treat Hodgkin lymphoma (HL). Your healthcare team will consider your personal needs to plan the type and amount of radiation, and when and how it is given. You may also receive other treatments.

Radiation therapy may be given after chemotherapy to treat classical HL or nodular lymphocyte-predominant HL (NLPHL) if there is lymphoma remaining.

It may be used alone to treat stage 1 and 2 (early) classical HL or NLPHL if you can’t have chemotherapy because you have other health problems or if the lymphoma cells are only in the area of the body where the cancer started (called localized disease).

Radiation therapy is given for different reasons. You may have radiation therapy or chemoradiation to:

• destroy cancer cells in the body
• destroy cancer cells left behind after chemotherapy to reduce the risk that cancer will come back (recur) (called adjuvant therapy)
• relieve pain or control the symptoms of advanced HL (called palliative 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. Doctors give radiation to the smallest area possible to help lower the risk of side effects.

Involved site radiation therapy (ISRT) means that radiation is given only to the lymph nodes where the HL started and a very small amount of nearby tissue.

Involved field radiation therapy (IFRT) means that radiation is given to lymph nodes that have HL and some of the tissue surrounding those lymph nodes. IFRT has a larger treatment area than ISRT.

Total body irradiation (TBI) means that radiation is given to the entire body. It may be used to prepare for a stem cell transplant.

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. 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 yet. People 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 HL, but everyone’s experience is different. Some people have many side effects. Other people 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 healthy cells can happen and may cause side effects. If you develop side effects, they 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, whether chemotherapy is also given and the treatment schedule. Some common side effects of radiation therapy used for HL are:

• fatigue
• skin problems
• sore throat
• taste changes
• nausea and vomiting
• diarrhea
• low blood cell counts (called bone marrow suppression)
• fertility problems (if the radiation includes exposure to the ovaries or testicles)
• heart problems
• lung problems
• thyroid problems
• second cancers

Tell your healthcare team if you have 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 you 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.