Radiation Therapy for Lung Cancer

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Radiation therapy is a medical procedure that uses the delivery of high-energy radiation to kill cancer cells and shrink tumors.

High-energy rays damage DNA in cells, causing them to die or stop dividing. Since cancer cells divide more frequently than normal cells, they are more susceptible to damage. Healthy cells can be affected as well but are better able to repair the damage.

When Is It Used?

Both small-cell and non-small cell lung cancers are frequently treated with radiation therapy, which is often combined with chemotherapy, surgery or both. More than half of those diagnosed with non-small cell lung cancer will receive radiation therapy at some time during their treatment. Depending upon the type and stage of your lung cancer, radiation therapy may be used:

  • After surgery – To treat any cancer cells that might remain in the area after surgery.
  • Before surgery – To decrease the size of a tumor and make surgery more effective.
  • To cure cancer – With small tumors, and in patients that are unable to have surgery due to age, location of a tumor or other medical conditions, radiation therapy can sometimes offer the chance for a cure.
  • To treat lung cancer – Both locally, such as nearby lymph nodes, and to other parts of the body, such as the brain.
  • To treat symptoms (palliative radiation therapy) – When a tumor is causing symptoms such as shortness of breath and pain, sometimes radiation therapy is used to reduce tumor size to decrease symptoms.
  • To treat lung cancer metastases - SBRT (see below) may at times be used to treat single or only a few brain metastases or liver metastases from lung cancer.
  • For prevention – In small-cell lung cancer, radiation therapy to the brain is sometimes given to kill any cells that have spread to the brain but are not detected by scans. This is called Prophylactic Cranial Irradiation (PCI).

How Is It Given?

Radiation therapy for lung cancer is often given daily, Monday through Friday, for a period of six weeks. Before treatment is started, you will be given one or more “tattoos,” permanent ink marks about the size of a freckle overlying the tumor in your lung. A simulation is then performed. During this procedure, you will need to lie very still on a table while the radiation oncologist figures out where to aim the radiation. The radiation oncologist will then calculate a dose of radiation (measured in Gy, pronounced grays) that will be delivered over the duration of your therapy.


Radiation therapy can be given externally or internally to treat lung cancer. Common procedures used include:

External beam radiation therapy - This is used most commonly and involves the use of an external machine that delivers high-dose radiation. The most common forms of external therapy are:

  • Conventional (two-dimensional) radiation therapy.
  • 3D conformational radiation therapy - This therapy expands on conventional therapy by using computed tomography (CT)-guided therapy to look at the tumor in three dimensions. The goal is to direct the radiation more specifically to the tumor and spare surrounding tissues.
  • Intensity Modulated Radiation Therapy (IMRT) - This therapy provides a higher dose of radiation from different angles. Studies have been finding that earlier and higher doses of radiation therapy delivered over a shorter period of time may improve survival rates but are also associated with increased toxicity, especially inflammation of the esophagus (radiation esophagitis.)

Internal radiation - Sometimes radiation is given internally for lung cancer. Internal radiation is also known as brachytherapy. During this procedure, a thin plastic tube is inserted during a bronchoscopy. A small amount of radioactive material is then passed through the tube, allowing the treatment to be delivered to a precise area. The tube is removed after treatment.

Stereotactic body radiotherapy (SBRT) - Stereotactic body radiotherapy or SBRT for lung cancer is a technique in which a high dose of radiation is delivered to a relatively small area of tissue in an attempt to rid the body of cancer. In contrast to other types of radiation therapy, SBRT is sometimes used with a curative intent with lung cancer. For some people with early stage lung cancer that is considered inoperable, SBRT may provide results similar to surgery. SBRT may also be used, at times, for lung cancer which has spread. When only a few metastases from lung cancer are present in the brain or liver, SBRT has on occasion resulted in long-term control of the disease.

Side Effects

Skin irritation, including redness and peeling, usually starts within the first week or two of treatment. Your oncologist may prescribe a cream for you and special attention to skincare is important. Fatigue is very common and may persist for several weeks beyond treatment. Pain or difficulty with swallowing (esophagitis) can occur and are reasons to contact your oncologist. Late symptoms such as radiation-induced lung damage can occur, but in most cases, the benefits of therapy far outweigh the risks of these complications.

It's important to become familiar with the possible side effects of radiation therapy before receiving these treatments. Side effects such as radiation pneumonitis - an inflammation of the lungs due to radiation therapy - are treatable, but may result in pulmonary fibrosis - permanent scarring - if not diagnosed and treated promptly.

As survival rates for lung cancer improve, it's also important to be aware of some of the long-term side effects of radiation therapy which may begin and persist month or year after radiation treatments are given. 

Follow-Up After Radiation Treatment

Radiation therapy can take a while to begin working but continues to work for some time after treatment has been completed. Your radiation oncologist will let you know when follow-up tests should be done to check on your progress.

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