Radiation therapy for non-small cell lung cancer

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 to the lungs are given 5 days a week for 4 to 7 weeks.

Standard (conventional) EBRT is used much less often than in the past. Newer techniques help doctors treat lung cancers more accurately while lowering the radiation exposure to nearby healthy tissues. These techniques may offer better chances of increasing the success rate and reducing side effects. Most doctors now recommend using these newer techniques when they are available.

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.

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) or stereotactic ablative radiotherapy (SABR), is sometimes used to treat very early stage lung cancers when surgery isn't an option due to issues with the patient’s health. Instead of giving small doses of radiation each day for several weeks, SBRT uses very focused beams of high-dose radiation given on one or a few days. Several beams are aimed at the tumor from different angles. To target the radiation precisely, the person is put in a specially designed body frame for each treatment. This reduces the movement of the lung tumor during breathing. Like other forms of external radiation, the treatment itself is painless.

Early results with SBRT have been very promising, and it seems to have a low risk of complications. But because it is still a fairly new technique, there isn't much long-term data on its use.

Another type of stereotactic radiation therapy can sometimes be used instead of surgery for single tumors that have spread to the brain. This is sometimes called stereotactic radiosurgery or SRS. In one version of stereotactic radiation therapy, a machine called a Gamma Knife® focuses about 200 beams of radiation 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. In another version, a linear accelerator (a machine that creates radiation) that is controlled by a computer moves around the head to deliver radiation to the tumor from many different angles.

Brachytherapy (internal radiation therapy)

Brachytherapy is used most often to shrink tumors to relieve symptoms caused by lung cancer in an airway, 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, but 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 along with chemotherapy), especially if the lung tumor cannot be removed by surgery because of its size or location, or if a person's health is too poor for surgery.

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. In some cases, radiation therapy may be used before surgery (usually along with chemotherapy) to try to shrink a lung tumor to make it easier to operate on.

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. For example, brachytherapy is most often used to help relieve blockage of large airways by cancer.

In some cases, doctors may recommend giving lower doses of radiation to the whole brain, even if there are no visible signs the cancer has spread there. The goal of this treatment, known as prophylactic cranial irradiation, is to try to prevent tumors from forming in the brain. Many doctors don't agree that the potential benefits of this treatment outweigh the possible side effects, however. If it is used, it is usually given 5 days a week over 2 weeks.

Possible side effects of radiation therapy

Common side effects of external radiation therapy include

• Sunburn-like skin problems
• Hair loss where the radiation enters the body
• Fatigue
• Nausea and vomiting
• Loss of appetite and weight loss

Often these go away after treatment. When radiation is given with chemotherapy, the side effects are often worse.

Chest radiation therapy may damage your lungs and cause a cough, problems breathing, and shortness of breath. These usually improve after treatment is over, although in some cases the symptoms may not go away completely.

Your esophagus, which is in the middle of your chest, may be exposed to radiation, which could cause a sore throat and trouble swallowing during treatment. This may make it hard to eat anything other than soft foods or liquids for a while.

Radiation therapy to large areas of the brain can sometimes cause 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 1 or 2 years after treatment.

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