Radiation Therapy


Radiation therapy may be used alone or in combination with surgery and/or chemotherapy in the treatment of primary or metastatic brain cancers, which are also called brain tumors. The three primary ways that radiation therapy is administered in the treatment of brain tumors are with:

  • External Beam Radiation Therapy (EBRT): a machine that directs radioactive beams from outside the body;
  • Stereotactic Radiation Therapy (Gamma Knife): a computer and image guided technique that directs radiation only at the tumor; and
  • Brachytherapy: a radioactive implant that is placed in or near the tumor.

EBRT is the conventional technique for administering radiation therapy to the brain, but stereotactic radiosurgery has also become a standard treatment. The most recent advance in the radiation treatment of brain tumors is the brachytherapy technique called GliaSite radiotherapy system, which involves placing a balloon in or near the tumor during surgery and then passing a radioactive material into the balloon for treatment.

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The following is a general overview of radiation therapy for brain tumors. Radiation therapy may be delivered as EBRT, brachytherapy, stereotactic radiation therapy, or through another, innovative technique. Combining two or more of these treatment techniques has become an important approach for increasing a patient’s chance of cure and prolonging survival.

In some cases, participation in a clinical trial utilizing new, innovative therapies may provide the most promising treatment. Treatments that may be available through clinical trials are discussed in the section titled Strategies to Improve Treatment .

Circumstances unique to each patient’s situation may influence how these general treatment principles are applied. The potential benefits of combination treatment, participation in a clinical trial, or standard treatment must be carefully balanced with the potential risks. The information on this Web site is intended to help educate patients about their treatment options and to facilitate a mutual or shared decision-making process with their treating cancer physician.

Procedures for Delivering Radiation Therapy to Brain Tumors

Treatment schedules: Radiation therapy often begins a week or two after surgery, or as soon as the surgical wound heals. Conventional EBRT is usually given in 30–40 doses over a six-week period, five days a week. Brachytherapy may be administered for only a few days, followed by removal of the radioactive “seed”, and stereotactic radiation therapy is typically conducted in one single session

Follow-up examinations: Results of therapy might not be obvious for several months or longer. Tumor cells that have been damaged by radiation cannot reproduce normally and gradually die. The brain clears away the dead tumor cells, but this is a lengthy process. Scans taken immediately following therapy can be confusing because swelling and dead cells often appear larger than the original tumor, and can cause symptoms similar to the tumor. It takes a few months before scans show the full benefit of the radiation.

Re-treatment with radiation: Radiation kills normal cells as well as tumor cells. Since brain tissue cannot replace itself, the effects of radiation are cumulative, causing severe side effects beyond a certain degree of exposure to radiation. For this reason, re-treatment with conventional fractionated radiation is not often recommended. However, additional radiation is possible in selected circumstances, including:

  • Location of the tumor and its relation to critical brain tissue,
  • When the previous radiation was given,
  • The amount of radiation originally given, and
  • The type of tumor and the age of the patient.

Brachytherapy and stereotactic radiation therapy are frequently used for selected patients who may benefit from retreatment with radiation therapy. These patients typically have recurrent malignant gliomas or metastatic brain tumors and have previously undergone conventional EBRT.

For more information about radiation therapy procedures, go to What to Expect During Radiation Therapy.

Techniques for Delivering Radiation Therapy to Brain Tumors
Side Effects and Complications of Radiation Therapy for Brain Tumors
Strategies to Improve Radiation Therapy for Brain Tumors