Radiation Therapy for Thymus Cancer
Radiation therapy is the use of high-energy radiation in the form of x-rays or radioactive particles to kill cancer cells.
Radiation therapy can be used in several situations. After surgery, radiation therapy is sometimes given to try to kill any small deposits of cancer that may have been left behind because they were too small to see. This, called adjuvant therapy, is done for nearly all stage III and IV thymomas and for most thymic carcinomas, even when no visible tumor was left behind.
Radiation may also be used after surgery if the doctor thinks that some cancer was left behind.
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. Some patients who can’t have surgery are treated with radiation therapy alone, although this is not as effective as surgery. Sometimes chemotherapy is given with radiation to help it work better.
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.
The type of radiation therapy used most often to treat thymic cancer is 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. The treatment is much like getting an x-ray, but the radiation is more intense. The procedure itself is painless, but it does cause side effects (discussed later on). 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. They may also do special CT scans to help plan your treatments. 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.
A type of EBRT called three-dimensional conformal radiation therapy (3D-CRT) is often used to treat thymic cancers. This technique allows doctors to more accurately target the tumor while reducing the radiation exposure to nearby healthy tissues such as the lungs and the heart. This might offer a better chance of increasing the success rate and reducing side effects.
Sometimes, an advanced form of 3D-CRT, called intensity-modulated radiation therapy (IMRT) is used. 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. Most major hospitals and cancer centers are now able to provide IMRT.
Possible side effects of radiation therapy for thymus cancer
Common side effects of radiation therapy include:
- Skin changes where the radiation passes through, such as redness and blistering
- Nausea, and vomiting
- Irritation of the esophagus (the tube between the mouth and stomach), which could cause problems such as painful swallowing
- Poor appetite and weight loss
- Diarrhea (if the abdomen/belly or pelvis is treated).
Radiation can damage bone marrow leading to low blood counts. This can lead to anemia (low red blood cell counts) which can cause people to feel weak and tired. It can also lead to low white blood cell counts, which increases the risk of serious infections.
Chest radiation therapy can also damage lungs. This can lead to trouble breathing and shortness of breath. Although this usually gets better after radiation treatments stop, sometimes the damage is long-term (or even permanent).
Most side effects are temporary and improve after radiation treatment is done.
If radiation therapy is used together with chemotherapy, the side effects are often worse.
If you are having any side effects from radiation therapy, tell your doctor or nurse. In most cases there are ways to help control these symptoms.
For more general information about radiation therapy, see Understanding Radiation Therapy: A Guide for Patients and Families.
Last Medical Review: February 7, 2014 Last Revised: March 17, 2015