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Radiation therapy uses high-energy rays (or particles) to kill cancer cells.

When is radiation therapy used?

Depending on the stage of small cell lung cancer (SCLC) and other factors, radiation therapy might be used:

• To treat the tumor and lymph nodes in the chest. In limited-stage SCLC, it might be used at the same time as chemotherapy (chemo). Giving chemo and radiation together is called concurrent chemoradiation.
• After chemo is finished. This is sometimes done for patients with extensive stage disease, or it can be used for people with limited stage disease who cannot tolerate getting chemotherapy and radiation at the same time.
• To help lower the chances of cancer spreading to the brain. This is called prophylactic cranial irradiation (PCI). This is usually given  to people with limited stage SCLC, but it can also help some people with extensive stage SCLC.
• To shrink tumors to relieve (palliate) symptoms of lung cancer such as pain, bleeding, trouble swallowing, cough, shortness of breath, and problems caused by spread to other organs such as the brain or bone.

Types of radiation therapy

The type of radiation therapy most often used to treat SCLC is called external beam radiation therapy (EBRT). A machine outside the body focuses radiation at the cancer.

Treatment is much like getting an x-ray, but the radiation dose is stronger. The procedure itself is painless, and each treatment lasts only a few minutes. Most often, radiation treatments as part of the initial treatment for SCLC is given once or twice daily, 5 days a week, for 3 to 7 weeks. Radiation to relieve symptoms and prophylactic cranial radiation (PCI) is given for shorter periods of time, typically less than 3 weeks.

Newer EBRT techniques have been shown to help doctors treat lung cancers more accurately while lessening the radiation exposure to nearby healthy tissues. These include:

• Three-dimensional conformal radiation therapy (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) is an advanced form of 3D therapy. The beams can be shaped and aimed at the tumor from several angles, and the strength of the beams can be adjusted to limit the dose reaching nearby normal tissues. This technique is used most often if tumors are near important structures such as the spinal cord. A variation of IMRT is called volumetric modulated arc therapy (VMAT). A machine delivers radiation quickly as it rotates once around the body. This allows each treatment to be given over just a few minutes.
• Four-dimensional conformal radiation therapy (4DCT) shows where the tumor is in relation to other structures during each part of the breathing cycle, as opposed to just giving a “snapshot” of a point in time, like a standard CT does. This technique might also be used to help show if a tumor is attached to or invading important structures in the chest, which could help doctors determine if a person might be eligible for surgery.
• Stereotactic body radiation therapy (SBRT), also known as stereotactic ablative radiotherapy (SABR), is most often used to treat early-stage SCLC when surgery isn’t an option due to a person’s health or in people who don’t want surgery. It might also be considered for tumors that have limited spread to other parts of the body, such as the brain or adrenal glands.

Instead of giving a small dose of radiation each day for several weeks, SBRT uses very focused beams of high-dose radiation given in fewer (usually 1 to 5) treatments. Several beams are aimed at the tumor from different angles. To target the radiation precisely, you are put in a specially designed body frame for each treatment. This reduces the movement of the lung tumor during breathing.

• Stereotactic radiosurgery (SRS) isn’t really surgery, but a type of stereotactic radiation therapy that is given in only 1 session. It can sometimes be used instead of or along with surgery for single spots tumor.

Possible side effects of radiation therapy for SCLC

If you are going to get radiation therapy, it’s important to ask your doctor beforehand about the possible side effects so that you know what to expect. Common side effects depend on where the radiation therapy is aimed and can include:

• Skin changes in the area being treated, which can range from mild redness to blistering and peeling
• Hair loss (in the area where the radiation enters the body)
• Fatigue (tiredness)
• Nausea and vomiting
• Loss of appetite and weight loss

Most of these side effects go away after treatment, but some can last a long time. When chemotherapy is given with radiation, the side effects may be worse.

Radiation therapy to the chest may damage your lungs, which might cause a cough, problems breathing, and shortness of breath. These usually improve after treatment is over, although sometimes they 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 or shortly after treatment. This might make it hard to eat anything other than soft foods or liquids for a while. This also often improves after treatment is finished.

Radiation therapy to large areas of the brain can sometimes cause memory loss, fatigue, headaches, or trouble thinking. Usually these symptoms are minor compared with those caused by cancer that has spread to the brain, but they can affect your quality of life.