Radiation therapy for Hodgkin lymphoma

Radiation therapy uses high-energy rays or particles to destroy cancer cells. The type of radiation therapy used for HL is external radiation therapy (also called external beam radiation therapy). During external radiation therapy, a machine directs radiation through the skin to the tumour and some of the tissue around it.

Most people with Hodgkin lymphoma (HL) have radiation therapy after they finish chemotherapy. Radiation therapy may also be used by itself when someone can’t have or doesn’t want to have chemotherapy.

Your healthcare team will use what they know about the cancer and about your health to plan the type and amount of radiation, and when and how it is given. You may have radiation therapy to:

• destroy cancer cells left behind after chemotherapy
• reduce the risk that cancer will come back (relapse or recur)
• relieve pain or control the symptoms of advanced HL (called palliative therapy)

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.

A radiation field is the area that is treated with radiation therapy. It usually includes the tumour and tissues near the tumour, including lymph nodes.

Giving radiation to the smallest area possible effectively treats HL and reduces the risk for long-term side effects of radiation therapy.

Involved-site radiation therapy (ISRT) means that radiation is given only to the lymph nodes where the HL started and a very small area of nearby tissue. It is used to reduce the risk that early-stage HL will come back (relapse or recur) after treatment.

Involved-field radiation therapy (IFRT) means that radiation is given to the lymph nodes that have HL and some of the tissue around them. IFRT has a larger treatment area than ISRT. It is used to reduce the risk that advanced HL will come back after treatment.

Total body irradiation (TBI) means that radiation is given to the entire body. It may also be called whole body radiation therapy. You may have TBI to prepare for a stem cell transplant.

During radiation therapy, your 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 and the treatment schedule. Tell your healthcare team if you have 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 you deal with them.

These are common side effects of radiation therapy for HL:

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

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.