Radiation therapy for thymus cancer

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

Most people with thymus cancer have radiation therapy. 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 surgery or chemotherapy to reduce the risk that the cancer will come back (may be called adjuvant radiation therapy or post-operative radiation therapy or PORT)
• shrink a tumour before other treatments such as surgery or chemotherapy (called induction radiation therapy)
• control the growth of cancer cells in the body when the cancer can't be removed with surgery (is inoperable)
• control pain and other symptoms of advanced thymus cancer (called palliative radiation therapy)

Radiation therapy and chemotherapy may be given during the same time period to treat thymus cancer, especially advanced or metastatic thymic carcinoma. This is called chemoradiation. Some chemotherapy drugs can help make radiation work better by making cancer cells more sensitive to radiation. Combining chemotherapy and radiation therapy can be more effective than either treatment on its own.

External radiation therapy is the type of radiation therapy most commonly used to treat thymus cancer.

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. It is usually given after surgery for thymus cancer (called post-operative radiation therapy or PORT).

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.

External radiation therapy is usually given once a day (5 days a week) for 5 to 7 weeks. How long treatment is used depends on factors such as the size and location of the cancer, the dose of radiation and your overall health.

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 the common side effects of radiation therapy for thymus cancer:

• fatigue
• skin problems
• problems swallowing
• upset stomach (indigestion)
• lung problems
• chest pain
• heart problems
• nausea and vomiting
• radiation pneumonitis

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