CyberKnife Radiosurgery for Astrocytomas

Approximately 18,000 people are diagnosed with brain cancer each year, and almost 13,000 Americans die of brain cancer yearly.  Brain cancer is slightly more common in men.  Prognosis is more favorable in younger (age under 40) patients.  Brain tumors can be classified as either benign or malignant.  Most astrocytomas are classified as malignant.  They invade surrounding normal brain tissue, and compromise normal brain function.  Astrocytomas are the most common malignant brain tumor.  The most aggressive of the astrocytomas is the glioblastoma multiforme.  Other malignant brain tumors include oligodendrogliomas and ependymomas.  There is usually no known cause in most patients who develop a brain tumor.

Malignant brain tumors

Malignant brain tumors are graded on a scale from 1 to 4, with 4 being the most aggressive.  As the grade of the tumor increases, the rapidity of growth and aggressiveness of the tumor tends to increase.The most common malignant primary brain tumors are the Grade 3 and 4 astrocytomas.  These tumors tend to be relatively large when they present, often measuring greater than 4 cm in size.  Common symptoms include headache, pressure symptoms such as nausea, gait instability, or seizure activity.  If possible, these tumors are completely resected, but it is often times impossible to completely resect them because of their proximity to or involvement of surrounding critical normal structures in the brain.

Treatment Options

Following surgery, whether biopsy or complete resection, radiation therapy and chemotherapy are usually recommended.  Several chemotherapeutic agents have recently been found to be useful in treating brain tumors, particularly temozolomide (Temodar ®).  These agents are generally well-tolerated and are leading to improved outcomes, although cure is still elusive.

CyberKnife® Radiosurgery Solutions

Treatment

Stereotactic radiosurgery can improve the quality of life and extend survival for patients with malignant brain tumors.  In the past, radiosurgery has been limited to tumors which are less than 4 cm in size, because of the limitations of having to place the patient in a head frame, and treating in only one session.  Cyberknife radiosurgery, by using the patient’s own anatomy for tumor tracking, makes the frame unnecessary; lesions which are larger or close to critical structures can now be treated safely.  Malignant brain tumors are often shaped very irregularly, and the robotic, non-isocentric delivery technique utilized by the Cyberknife makes it possible to optimally conform the dose of radiation.

Following Cyberknife radiosurgery for treatment of a malignant brain tumor, the patient usually returns home the same day.  Mild fatigue is common, but nausea or worsening of the patient’s condition is unusual.  Patients who are on seizure medications will remain on these until advised to do otherwise by their neurosurgeon or radiation oncologist.  Hair loss is unlikely, and if it does occur, it is usually limited to a small portion of the scalp.

Effectiveness

Because the Cyberknife is so precise, radiosurgery can often times be repeated again at a later date if necessary, in order to provide continued benefit for the patient.

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