Treatment Options

• Surgery to remove the tumor
• Radiation therapy

The goal of surgery is to remove as much of the tumor as possible without damaging the brain. However, tumors are not easily removed. The tumor can spread into healthy parts of the brain and make it difficult to remove all of the cancer. The surgeon will remove as much of the tumor as possible to relieve the patient's symptoms. Then, radiation (and sometimes chemotherapy) is used to treat the remaining cancer. If the tumor cannot be surgically removed, radiation and/or chemotherapy may still be used to treat the cancer.

Radiation Therapy

Radiation therapy (also called radiotherapy) is the use of high-energy X-rays to damage cancer cells and stop or slow them from growing. The ability of radiation to stop a tumor from growing depends on the type and size of tumor being treated and its sensitivity to radiation. It is often used to destroy tumor tissue that cannot be removed with surgery or to kill cancer cells that may remain after surgery. Radiation therapy is also used when surgery is not possible. Studies have shown that patients treated with radiation live longer.

There are several types of radiation therapy:

• External radiation
• Stereotactic radiosurgery
• Internal radiation

External radiation therapy is the most common type of radiation therapy. A carefully controlled beam of radiation travels through the brain to reach and destroy the cancer. Generally, external radiation treatments are given 5 days a week for 5 to 6 weeks. The treatment schedule depends on the type and size of the tumor and the age of the patient. External radiation may be directed just to the tumor and the tissue close to it or to the entire brain. Sometimes a form of local radiation may be used in addition to, or following, external beam radiation. That is called a radiation “boost.”

Stereotactic radiosurgery is another way to deliver external radiation to treat certain types of brain tumors. It is most frequently used for those that are inoperable (cannot be reached through traditional surgery) or do not require surgical resection. Doctors use sophisticated equipment—a special headframe and CT scans or MRI—to pinpoint the tumor’s location. Treatment is given in one session. High-energy X-rays are aimed at the tumor from many angles to provide a high dose of radiation at the tumor site.

While stereotactic radiosurgery has been shown to be effective for treating small, multiple or inoperable tumors, it does have limitations when irradiating large volumes of tissue or the tumor margins following surgical removal of a tumor. The delivery of high-dose-rate radiation by radiosurgery also has severe limits with respect to the volumes to which an effective dose can be delivered with an acceptable rate of complications. ¹

Internal radiation therapy offers additional benefits as an alternative to external beam radiation. Also known as brachytherapy, localized radiation, or interstitial radiation, internal radiation therapy involves placing a source of radiation directly into the tumor or the tissue surrounding the tumor.

The major benefit of internal radiation is that a high dose of radiation may be given directly to the tumor site. The radiation is targeted in the area most likely to contain cancer. At the same time, healthy tissue around the tumor is less likely to be damaged by radiation. Good clinical results have been documented using this type of radiation therapy. ^1-4

This approach is frequently used to deliver radiation to a recurrent brain tumor. Brain tumors often recur within a short period of time, usually at or near the original surgical removal site. At present, treatment options after recurrence of a tumor are limited. External radiation therapy, while effective at treating brain cancer, does cause some damage to healthy brain tissue. For most patients, a second round of external beam therapy (to treat a recurrent tumor) would be too risky to their health. The risk of healthy tissue damage would outweigh the benefits of another treatment with external beam radiation.

Unlike external beam radiation, internal radiation therapy does not require the radiation to pass through healthy tissue to reach the cancerous area. Because of this, internal radiation is an option even for patients who have already had external beam radiation.

Internal radiation therapy is also used to treat metastatic tumors and to provide a boost dose with external beam radiation for initial tumor treatment.

Historically, brachytherapy involved the placement of a large number of radiation “seeds” (approximately the size of a grain of rice) directly into the cancerous tissue using numerous tube-like catheters. Until now the complexity and complications associated with internal radiation delivery have limited use of the therapy. The GliaSite Radiation Therapy System (RTS) has made this effective treatment easier to use.

References:

¹ Tatter, et al. An inflatable balloon catheter and liquid ¹²⁵I radiation source (GliaSite Radiation Therapy System) for treatment of recurrent malignant glioma: multicenter safety and feasibility trial. J. Neurosurgery. 2003; 99: 297-303.
² Halligan, et al. Operation and permanent low activity ¹²⁵I brachytherapy for recurrent high grade astocytomas. Int J Rad Onc Biol Phys. 1996;35:541-547.
³ Wen, et al. Long-term results of stereotactic brachytherapy used in the initial treatment of patients with glioblastomas. Cancer. 1994;73:3029-3036.
⁴ Loeffler, et al. Results of stereotactic brachytherapy used in the initial management of patients with glioblastoma. J Natl Cancer Inst. 1990;82:1918-1921.