Radiation therapy for lung cancer

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Radiation therapy uses high-energy rays or particles to destroy cancer cells. Most people with lung cancer have radiation therapy. 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 often combined with chemotherapy to treat lung cancer. This is called chemoradiation. The 2 treatments are given during the same time period. You will not be offered chemoradiation if you aren't healthy enough to have this type of treatment.

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

  • as the main treatment for lung cancer that can't be removed with surgery, or if you don't want to have surgery

  • after surgery to lower the risk of the cancer coming back (recurring) (called adjuvant therapy)

  • to relieve pain or control the symptoms of advanced lung cancer (called palliative therapy)

  • to treat lung cancer that has spread to the brain (brain metastases)

  • to prevent small cell lung cancer from spreading in the brain

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

External radiation therapy

During external radiation therapy, a machine directs radiation through the skin to the tumour and some of the tissue around it.

Before radiation therapy is started, your treatment is planned carefully. The radiation healthcare team measures how your lungs move when you breathe and maps the shape of your internal organs. This helps the radiation team to plan the best way of giving you external radiation therapy. The goal is to aim the radiation at the tumour while lowering the amount of radiation to surrounding tissue.

External radiation therapy is usually given 5 days a week, for 5 to 7 weeks. If it is being used as a palliative therapy, it may not be given for as long.

There are several different ways to give external radiation therapy for lung cancer.

3-D conformal radiation therapy (3-D CRT)

The most common form of external radiation therapy is 3D-CRT. Radiation beams that are all the same strength are aimed from several different directions at the tumour. A CT scan is used to guide the radiation beams to the tumour.

Intensity-modulated radiation therapy (IMRT)

IMRT is a much more targeted way of giving radiation therapy than 3D-CRT. The radiation beams are given in small beams that are shaped by a machine called a multi-leaf collimator. The strength of the beams is different across the treatment area so that the tumour gets the most radiation and nearby tissue gets less. IMRT is often used if the treatment area includes important areas of the body such as the spinal cord.

Stereotactic body radiotherapy (SBRT)

SBRT is a way of giving radiation therapy from several different positions around the body. Using a CT scan for guidance, radiation beams are directed to all meet at a point in the tumour. This is a very accurate way of giving radiation because the tumour gets a high dose of radiation while the surrounding tissue gets lower doses. SBRT is sometimes called stereotactic ablative radiotherapy (SABR).

SBRT for lung cancer is given over 7 to 10 days, which is much shorter than other ways of giving radiation therapy.

You may be offered SBRT if you have lung cancer that hasn't spread outside of the lung or if you can't have or don't want to have surgery.

Hypofractionated radiation therapy

With hypofractionated radiation therapy, fewer radiation treatments are given. This is done by giving either a short course of daily treatments or by giving fewer large doses (sometimes just a single treatment).

You may be offered hypofractionated radiation therapy if you are not able to have the high doses of radiation given during SBRT.

Prophylactic cranial irradiation (PCI)

Prophylactic cranial irradiation (PCI) is external beam radiation given to the whole brain. It is used to prevent small cell lung cancer from spreading to the brain or to treat cancer cells that may have already spread there but cannot be seen by imaging tests. It may help prevent brain metastases and improve survival.

PCI is offered to people with limited and extensive stage small cell lung cancer that has responded well to chemotherapy and radiation therapy. It is not offered to people with small cell lung cancer that has not responded to chemotherapy.

PCI is not used to treat non-small cell lung cancer because research has shown it does not improve survival or quality of life.


Brachytherapy is a type of internal radiation therapy that places radioactive material in the body. This is done during a bronchoscopy using a small tube called a catheter that goes through the bronchoscope. At the end of the treatment, which usually takes less than 30 minutes, the radioactive material is removed from the lung through the catheter. No radioactive material is left inside the body. As the radiation effect kills the cancer cells over 2 to 4 weeks, the tumour shrinks.

Brachytherapy may be used to treat a tumour that is blocking an airway of the lung. It may also be used as a primary treatment if you cannot have external radiation therapy because of poor lung function. This can also be called endobronchial brachytherapy or endobronchial radiation therapy.

Side effects

Side effects can happen with any type of treatment for lung cancer, 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, the treatment schedule and if radiation therapy is being given with chemotherapy. Some common side effects of radiation therapy used for lung cancer are:

Some side effects of prophylactic brain irradiation 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

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