Radiation therapy for thymus cancer

Radiation therapy uses high-energy rays or particles to destroy cancer cells. It is usually used to treat thymus cancer. 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 is sometimes given at the same time as chemotherapy to treat thymus cancer. This is called chemoradiation.

Radiation therapy is given for different reasons. You may have radiation therapy alone or at the same time as chemotherapy to:

  • destroy cancer cells left behind after surgery or chemotherapy to reduce the risk that the cancer will come back (called adjuvant therapy)
  • shrink a tumour before other treatments such as surgery or chemotherapy (called induction therapy)
  • control the growth of cancer cells in the body when surgery can’t be done (is inoperable)
  • control pain and other symptoms of advanced thymus cancer (called palliative therapy)

The following types of radiation therapy are most commonly used to treat thymus cancer.

External radiation therapy

During external radiation therapy (also called external beam radiation therapy), a machine directs radiation through the skin to the tumour or the area where the tumour was removed and some of the tissue around it. It can be given alone or at the same time as chemotherapy.

External radiation therapy is mainly used for stage 3 and stage 4 thymus cancers. Depending on the size of the tumour, it can be given before or after surgery. But it may be used for some cases of stage 1 or stage 2 thymus cancer, such as if:

  • the cancer was not completely removed by surgery
  • there is cancer in the surgical margin or close to it
  • the cancer is classified as World Health Organization (WHO) type B1, B2 or B3
  • the cancer is thymic carcinoma
  • the tumour is attached to the pericardium

External radiation therapy may also be used as a main treatment if surgery can’t be done.

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, when the radiation is given, the dose of radiation and your overall health.


Brachytherapy is a type of internal radiation therapy. It uses a radioactive material called a radioactive isotope. It is placed right into the tumour or very close to it. Radioactive materials can also be placed in the area where the tumour was removed. The radiation kills the cancer cells over time.

Brachytherapy is not usually used. But it may be given as palliative therapy for thymoma that has spread to the bronchi (endobronchial), especially when external radiation therapy has already been used. It is given as one high dose of radiation in a short period of time (called high-dose-rate brachytherapy).

Side effects

Side effects can happen with any type of treatment for thymus cancer, but everyone’s experience is different. Some people have many side effects. Other people have few or none at all.

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.

Radiation therapy is very carefully planned to make sure that the organs near the thymus (the heart and lungs) are protected from radiation as much as possible, while ensuring that the area with the cancer is treated.

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 whether it is given at the same time as chemotherapy. Some common side effects of radiation therapy used for thymus cancer are:

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.

Questions to ask about radiation therapy

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.

Expert review and references