Radiation therapy is the use of high-energy radiation in the form of x-rays or radioactive particles to kill cancer cells.

There are several situations in which radiation therapy might be used. After surgery, radiation therapy can be used as adjuvant (additional) therapy to try to kill any small deposits of cancer that may not have been removed during surgery. This is done for nearly all stage III and IV thymomas and for all thymic carcinomas.

Some doctors may use radiation therapy to try to shrink larger tumors before surgery, especially if the tumor isn't completely resectable. But not all doctors agree this is useful. Radiation therapy is not as effective when used alone to treat thymic cancer, although it may be an option for patients too ill to tolerate an operation.

In people with advanced disease, radiation therapy can be used to help ease (palliate) symptoms from the cancer such as shortness of breath, pain, bleeding, or trouble swallowing.

External beam radiation therapy (EBRT): This type of radiation therapy uses x-rays from a machine outside the patient's body to kill cancer cells. It is the most common form of radiation therapy for thymic cancer. The treatment is much like getting an x-ray, but the radiation is more intense. The procedure itself is painless. Before your treatments start, the medical team will take careful measurements to determine the correct angles for aiming the radiation beams and the proper dose of radiation. 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 several weeks.

With newer techniques, doctors can more accurately treat thymic cancers while reducing the radiation exposure to nearby healthy tissues such as the lungs. This may offer a better chance of increasing the success rate and reducing side effects.

For example, intensity-modulated radiation therapy (IMRT) is an advanced form of three-dimensional radiation therapy. It uses a computer-driven machine that moves around the patient as it delivers radiation. Along with shaping the radiation 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. Many major hospitals and cancer centers are now able to provide IMRT.

Possible side effects of radiation therapy

Side effects of radiation therapy may include fatigue and mild skin changes that resemble sunburn. These usually go away once treatment is finished. Chest radiation therapy may cause lung damage and lead to trouble breathing and shortness of breath. It can also affect the esophagus (the tube between the mouth and stomach), which could cause problems with swallowing. Abdominal radiation therapy may cause nausea, vomiting, and diarrhea.

If radiation therapy is used together with chemotherapy, it may make the side effects of chemotherapy worse.

If you are having any side effects from radiation therapy, talk with your doctor or nurse. In most cases there are ways to help control these symptoms.

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

Last Medical Review: 05/18/2009
Last Revised: 05/18/2009