CyberKnife Therapy for Brain Tumors
Frequently Asked Questions
» What is CyberKnife, and how can it be used to treat brain tumors?
» When was CyberKnife approved to treat brain tumors?
» What are CyberKnife's advantages for brain tumor treatment?
» How effective is CyberKnife in the treatment of brain tumors?
» What is the process involved in receiving CyberKnife therapy for brain tumors?
» What side effects may be associated with CyberKnife brain tumor treatment?
» How do brain tumors respond to CyberKnife treatment?
Q. What is CyberKnife and how can it be used to treat brain tumors?
CyberKnife is a robotically controlled radiation delivery machine. Although it can treat tumors anywhere in the body, it was originally developed primarily as a device to deliver Stereotactic Radiosurgery (SRS) for tumors of the brain. In fact, SRS has been used for more than four decades to treat brain lesions.
SRS is a radiation treatment technique in which high doses of radiation are delivered using very precise beams during a single treatment session. With this technique, hundreds of separate, narrow beams of radiation are focused on the tumor, allowing a very high amount of radiation to be delivered to a very small target in the brain. The aim is to use such a high dose that the tumor is destroyed. The CyberKnife allows the delivery to be performed with great precision.
Other SRS techniques may require patients to be immobilized with their heads locked in place using tight holding devices or frames that are sometimes screwed into the skull. This is to ensure that the radiation is delivered accurately, and that the patient and tumor do not move during treatment. In this way, the tumor is specifically targeted, and surrounding normal brain tissue received lower radiation doses. The radiation delivered by the CyberKnife machine is the same type used in standard radiation machines. However, with CyberKnife treatment, the invasive head-holding frame is no longer needed.
Throughout Cyberknife treatment, digital X-ray images are taken to ensure that the patient and tumor are tracked and targeted. These digital images are then monitored electronically in real time to track tumor and patient movement and guide the robotic radiation delivery system. The result is an SRS delivery system that is accurate to less than 1 millimeter, and can accomplish treatments quickly with greater patient comfort. This technology also allows doctors to precisely treat tumors in delicate areas of the brain by easily dividing the treatment into multiple sessions, therefore lowering the risk of side effects and damage to critical areas of the normal brain.
Q. When was CyberKnife approved to treat brain tumors?
CyberKnife was cleared by the U.S. Food & Drug Administration (FDA) in 1999 to treat tumors in the head and base of the skull.
Q. What are CyberKnife’s advantages for brain tumor treatment?
Standard treatments for brain tumors include standard external beam radiation, surgery and chemotherapy. Because CyberKnife involves no cutting, it offers some patients a non-invasive alternative to brain cancer surgery. It can be used for brain tumors that are considered inoperable because of their location in the head, for patients who cannot undergo brain surgery because of their poor medical condition, or for those who refuse surgery. The CyberKnife System can also treat benign tumors, like meningiomas and schwannomas, and other noncancerous conditions, such as trigeminal neuralgia and arterial venous malformations (AVMs).
The CyberKnife image-guided robotic delivery system allows brain tumor treatment without a head-immobilizing frame, resulting in greater patient comfort, shorter treatment time, and the ability to easily treat some brain tumors in more than one treatment session, thereby improving treatment safety and lowering side effects.
Q. How effective is CyberKnife in the treatment of brain tumors?
CyberKnife has a strong record of clinical effectiveness for many brain tumors. A 2001 Stanford University study found benefits for a broad range of brain and spine tumors, many of which were otherwise untreatable. It concluded that the CyberKnife is becoming an increasingly accepted method for performing radiosurgery. A 2003 Stanford study of patients with intracranial and extracranial tumors showed CyberKnife’s precision to be comparable to older, frame-based systems in which the head is immobilized with uncomfortable devices.
A 2008 Stanford study showed treatment of benign brain tumors with CyberKnife was effective in 91 percent of patients at controlling or shrinking the tumors. Another 2008 study, done in Germany, found CyberKnife could be used as a primary therapy for brain tumor patients. A 2009 Chinese study found CyberKnife achieved “perfect” clinical outcomes using its higher dosage and concluded it is an “appropriate and valid” treatment for cancer that has metastasized to the brain.
Published studies from Beth Israel Deaconess Medical Center, using our CyberKnife system, have shown safe and effective treatment for benign and malignant tumors, such as brain metastases, meningiomas, schwannomas, AVMs and glioblastoma.
Q. What is the process involved in receiving CyberKnife therapy for brain tumors?
CyberKnife brain cancer treatments are typically performed on an outpatient basis over a period of one to five days and do not require overnight stays. Most patients experience minimal to no side effects with a quick recovery time.
Patients are treated by a team which includes a neurosurgeon, a radiation oncologist, a radiation therapist, and other support personnel. The process involves setup and imaging, treatment planning, and CyberKnife treatment.
Before treatment begins, the brain is imaged by CT, MRI or PET scan to precisely determine the location of the tumor. The patient wears a plastic mesh mask during the imaging process to help him or her keep still. The mask is also worn during treatments.
The data gained through imaging is used to design a custom treatment plan. Treatment may occur in one or several sessions over the course of several days. During treatment, patients dress in their own clothes and may listen to music. In the course of treatment, the system’s computer-controlled robot moves around the body to the various locations from which it will deliver the radiation.
Q. What side effects may be associated with CyberKnife brain tumor treatment?
Most side effects disappear quickly. They can include fatigue, and headaches. Neurological symptoms such as seizures are rare. Scarring and tissue injury also occur in rare cases.
Q. How do brain tumors respond to CyberKnife treatment?
Patients are advised that their tumors will not immediately disappear and that it may take months to determine the effectiveness of the treatment, including stability of the treated area.