Radiation therapy uses high-energy rays (such as x-rays) or particles to kill cancer cells. There are 2 main types of radiation therapy -- external beam radiation therapy and brachytherapy (internal radiation therapy).

External beam radiation therapy

External beam radiation therapy (EBRT) focuses radiation delivered from outside the body on the cancer. This is the type of radiation therapy most often used to treat a primary lung cancer or its metastases to other organs.

Before your treatments start, the radiation team will take careful measurements to determine the correct angles for aiming the radiation beams and the proper dose of radiation. Radiation therapy is much like getting an x-ray, but the radiation is stronger. The procedure itself is painless. Each treatment lasts only a few minutes, although the setup time -- getting you into place for treatment -- usually takes longer. Most often, radiation treatments are given 5 days a week for 5 to 8 weeks.

Standard (conventional) EBRT is used much less often than in the past. Newer techniques allow doctors to be more accurate in treating lung cancers while reducing the radiation exposure to nearby healthy tissues. These techniques may offer better chances of increasing the success rate and reducing side effects.

Three-dimensional conformal radiation therapy (3D-CRT): 3D-CRT uses special computers to precisely map the location of the tumor(s). Radiation beams are shaped and aimed at the tumor(s) from several directions, which makes it less likely to damage normal tissues. Most doctors now recommend using 3D-CRT when it is available.

Intensity modulated radiation therapy (IMRT): IMRT is an advanced form of 3D therapy. It uses a computer-driven machine that moves around the patient as it delivers radiation. Along with shaping the beams and aiming them at the tumor from several angles, the intensity (strength) of the beams can be adjusted to minimize the dose reaching the most sensitive normal tissues. This technique is used most often if tumors are near important structures such as the spinal cord. Many major hospitals and cancer centers are now able to provide IMRT.

Stereotactic radiation therapy: A newer form of treatment, known as stereotactic body radiation therapy (SBRT), is sometimes used to treat very early stage lung cancers. It is described in more detail in the section, "What's new in non-small cell lung cancer research and treatment?"

Another type of stereotactic radiation therapy can sometimes be used instead of surgery for single tumors that have spread to the brain. Using a machine called a Gamma Knife^®, many beams of high-dose radiation are focused on the tumor from different angles over a few minutes to hours. The head is kept in the same position by placing it in a rigid frame.

Brachytherapy (internal radiation therapy)

Brachytherapy is used most often to shrink tumors to relieve symptoms caused by the cancer, although in some cases it may be part of a larger treatment regimen trying to cure the cancer. For this type of treatment, the doctor places a small source of radioactive material (often in the form of pellets) directly into the cancer or into the airway next to the cancer. This is usually done through a bronchoscope, although it may also be done during surgery. The radiation travels only a short distance from the source, limiting the effects on surrounding healthy tissues. The radiation source is usually removed after a short time. Less often, small radioactive "seeds" are left in place permanently, and the radiation gets weaker over several weeks.

When is radiation therapy used?

External beam radiation therapy is sometimes used as the main treatment of lung cancer (sometimes together with chemotherapy), especially if the lung tumor cannot be removed by surgery because of its size or location, or because the person's health is too poor for surgery. Brachytherapy is most often used to help relieve blockage of large airways by cancer.

After surgery, radiation therapy can be used (alone or along with chemotherapy) to try to kill very small deposits of cancer that surgery may have missed.

Radiation therapy can also be used to relieve (palliate) symptoms of advanced lung cancer such as pain, bleeding, trouble swallowing, cough, and problems caused by brain metastases.

Possible side effects

Side effects of external radiation therapy might include sunburn-like skin problems where the radiation enters the body, nausea, vomiting, and fatigue. Often these go away after treatment. Radiation might also make the side effects of chemotherapy worse.

Chest radiation therapy may damage your lungs and cause problems breathing and shortness of breath. Your esophagus, which is in the middle of your chest, may be exposed to radiation, which could cause trouble swallowing during treatment. This usually improves after treatment is over.

Radiation therapy to large areas of the brain can sometimes cause changes in brain function. Some people notice memory loss, headache, trouble thinking, or reduced sexual desire. Usually these symptoms are minor compared with those caused by a brain tumor, but they can reduce your quality of life. Side effects of radiation therapy to the brain usually become most serious 1or 2 years after treatment.

For more information about radiation therapy, please see the document, Understanding Radiation Therapy: A Guide for Patients and Families.

Last Medical Review: 10/20/2009
Last Revised: 10/20/2009