Medical Health Encyclopedia

Radiation Therapy in Metastasis to the Brain. Radiation is the primary treatment when cancer has spread to the brain unless the cancer is small enough to be treated surgically. In such cases, a technique called stereotactic radiosurgery may be employed that delivers powerful, highly targeted radiation to specific areas in the brain. Some trials are investigating using radiation to the head in order to prevent metastasis to the brain.

Standard Radiation Procedures

The goal of radiation treatment is to administer doses as high as possible to kill as many cancer cells as possible, without destroying surrounding healthy tissues or causing excessive toxicity. Different procedures may be tried. The exact radiation procedure depends on the site of the cancer or its extent:

• External-Beam Radiation. External-beam radiation therapy focuses a beam of radiation directly on the tumor. It is generally used for metastasized cancer.
• Brachytherapy. Brachytherapy involved the implantation of radioactive seeds through thin tubes directly into the cancer sites. Brachytherapy may be used for lung cancers that have spread to the throat and cause obstruction. High-dose-rate brachytherapy may also have some value for patients who have inoperable tumors in the central region of the lung.

Hyperfractionated Radiotherapy

Hyperfractionated radiotherapy administers smaller than standard doses a number of times a day (usually two or three). This allows a higher cumulative dose over the whole course of treatment. It is not as useful as sole therapy, but needs to be combined with chemotherapy to have any survival benefits.

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Hyperfractionated Accelerated Radiotherapy. Continuous hyperfractionated accelerated radiotherapy (CHART) administers multiple doses per day but uses standard doses. This allows the total dose of radiation to be administered over a shorter time period than the standard six weeks. CHART is proving to extend survival rates of patients with localized cancer over that of standard radiotherapy or non-accelerated hyperfractionated radiation. It can cause severe swallowing problems. A modification in which treatment is suspended for two days out of seven may help reduce this effect.

Three-Dimensional Conformal Radiotherapy