The revolutionary CyberKnife treatment technology is not new; the CyberKnife System has more than two decades of clinical proof and has helped thousands of patients with various brain tumors and metastases.1,2
The CyberKnife System was cleared by the U.S. Food and Drug Administration in 1999 to treat diseases in the head and base of the skull, including, but not limited to, benign and malignant primary tumors, brain metastases, meningiomas, trigeminal neuralgia, acoustic neuromas, arteriovenous malformations (AVMs) and functional disorders. CyberKnife radiosurgery is even used to treat complicated neurosurgical cases, while maximally sparing brain tissues involved in important functions such as motor control, touching, hearing and vision.
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The CyberKnife System offers many of the same benefits of precise surgical intervention. However, treatment with the CyberKnife System is not surgical at all. CyberKnife radiosurgery is an outpatient procedure that does not require incisions or general anesthesia. Most patients will not require hospitalization or a long recovery period. Compared with single-session radiosurgery with the frame-based Gamma Knife, treatment with the CyberKnife System can be spread out over 1-5 sessions, which may result in fewer side effects.
Radiation therapy is a treatment that uses high-energy X-rays (photons) to kill, shrink or control the growth of tumors. Radiation therapy works by damaging cells, disabling them from growing and dividing. The goal of any radiation treatment is to destroy cancer cells while minimizing the side effects on healthy tissue. As imaging technologies have improved over the last several decades, radiation therapy has integrated those improvements to enhance dose delivery and minimize side effects.
Radiation may be recommended as an alternative to surgery or in addition to other therapies. There are several kinds of radiation therapy. The CyberKnife System delivers a type of radiation therapy known as stereotactic radiosurgery (SRS).
Stereotactic radiosurgery (SRS) couples a high degree of targeting accuracy with very high doses of radiation, minimizing the dose on other nearby organs. The treatment is administered in 1 to 5 sessions to the brain or the spine, typically by a team involving a radiation oncologist and a neurosurgeon. This treatment does not involve surgery.
The extreme, targeted precision of stereotactic radiosurgery (SRS) with the CyberKnife System can offer several powerful benefits, including:
- Non-surgical and non-invasive
- Good cancer control
- Significantly reduced incidence of common cognitive side effects (memory and concentration impairments)
- Treatments can be completed in as little as 1 visit in 1 day but can be extended to 1–5 sessions within 1-2 weeks, depending on the case
- Most patients can continue normal activity throughout treatment
- Does not typically interrupt chemotherapy cycles
- Patients whose brain tumors were previously irradiated can receive CyberKnife SRS treatment
Instead of delivering radiation to all brain tissues, CyberKnife radiosurgery targets the tumor(s) with sub-millimeter precision, protecting healthy brain tissues and reducing the risk of common cognitive side effects of whole-brain radiation. In addition, CyberKnife radiosurgery can be completed in just 1 to 5 sessions in 1 to 2 weeks, compared with 10 to 15 sessions over two or three weeks with conventional whole-brain radiation.
Compared with single-session radiosurgery with the frame-based Gamma Knife, treatment with the CyberKnife System can be spread completed in one to five sessions, which may result in fewer side effects3. CyberKnife multi-session radiosurgery has been shown to enable safer treatment of tumors close to sensitive structures in the head and neck4,5,6,7,8,9. CyberKnife treatments are more comfortable as no head frame is required to immobilize the patient.
Stereotactic radiosurgery (SRS) with the CyberKnife System can offer a powerful alternative to surgical intervention and conventional whole-brain radiation therapy. CyberKnife SRS treatment is frequently used to treat the following types of cases:
- Brain Metastases
When cancer is limited to one (or a small number) of well-defined tumors in the brain, radiosurgery can provide a more focused treatment than conventional whole-brain radiation.
- Radiation-Resistant Tumors
Some types of brain tumors do not respond well to the low doses of frequent radiation used in conventional whole-brain radiation. However, these radiation-resistant tumors can be effectively treated with high-dose radiation treatment using CyberKnife radiosurgery.
- Avoiding Chemotherapy or Immunotherapy Interruption
Many patients respond well to multi-modality treatment that combines radiation therapy with systemic treatment such as chemotherapy or immunotherapy. Unlike conventional whole-brain radiation, which may require interrupting chemotherapy treatment for several weeks, CyberKnife radiosurgery can be completed in as little as 1-5 visits and typically does not require interruption to the chemotherapy cycle or immunotherapy treatments.
- Patients with Prior Brain Irradiation
In the event of a recurrence, it is generally not possible for patients to undergo a second course of whole-brain radiation. Because CyberKnife radiosurgery delivers precisely targeted radiation, it may provide a safe radiation treatment option for some previously irradiated tumors. In addition, clinical data indicates that patients previously treated with CyberKnife radiosurgery (SRS) can be safely and effectively treated with additional courses of SRS — thereby delaying or completely avoiding whole-brain irradiation10.
- Reducing the Risks of Cognitive Impairment
In some cases, both whole-brain radiation and targeted radiosurgery may be viable treatment options. Both treatments can provide good long-term cancer control, but patients may choose radiosurgery in an effort to reduce the risk of cognitive side effects to memory and concentration.
- Complicated Brain Tumors
For tumors and lesions located in the vicinity of sensitive structures that impact functions like motor control, touching, hearing and vision, the CyberKnife System can provide an extremely targeted treatment that minimizes dose to these sensitive surrounding tissues — helping to reduce the risk of short- and long-term impairments.
Treatment with the CyberKnife System is well-tolerated with a low risk of toxicity. Side effects associated with CyberKnife treatment are usually mild and temporary. As with any radiation treatment, side effects can also be severe in some patients and lead to permanent injury or even death. Discuss your specific case with your physician/s to fully understand the potential risks associated with your treatment. Possible side effects could include but not limited to:
- Increased intracranial pressure expressed by:
- Orthostatic hypotension
- Edema (causing headache)
CyberKnife treatment can be completed in as little as 1-5 sessions over 1-2 weeks, compared to conventional whole-brain radiation therapy which typically takes 10 to 15 sessions over 2 or 3 weeks.
Treatment with the CyberKnife System is a non-surgical and outpatient procedure that does not require incisions or general anesthesia. Most patients will not require hospitalization, or a long recovery time. The majority of patients can continue normal activity during and immediately following treatment.
No anesthesia is required for CyberKnife treatment and treatment sessions are completed on an outpatient basis.
The majority of patients can continue normal activity during and immediately following CyberKnife treatment – compared to the typical requirement to limit normal activity for several weeks or more with traditional brain cancer surgery.
The majority of patients can continue normal activity during and immediately following CyberKnife treatment — compared to the typical limitations that come with traditional surgical treatments. And because radiosurgery greatly reduces the risk of cognitive impairments that may be associated with traditional whole-brain radiation therapy or surgery, the CyberKnife can help you get back to a healthy, full life, sooner.
The robotic design, combined with real-time imaging and automatic synchronization of the radiation beam with skull movement, enables the CyberKnife System to deliver a maximum dose of radiation directly to the tumor from virtually any angle with sub-millimeter precision throughout treatment delivery. Greater precision helps minimize dose to surrounding healthy tissues, reducing the risk of many common side effects11, 12.
When sub-millimeters matter, even slight skull motion, patient movements or shifts in the position of the tumor can be significant. Failing to synchronize the delivery of radiation dose with skull movement can result in decreased dose delivered to the target — and increased dose delivered to surrounding healthy tissues. This can impact the overall effectiveness of the treatment and can potentially increase the incidence and severity of side effects.
Unlike any other radiation treatment, the CyberKnife System continually tracks, automatically adapts and synchronizes treatment delivery with movement of the patient, skull motion and tumor in real-time throughout the entire treatment session. This helps ensure the radiation dose is delivered with sub-millimeter accuracy to the target — maximizing treatment effectiveness while minimizing does to surrounding tissues to reduce the incidence of side effects.
The tissues and structures of the brain are among the most delicate and important for maintaining everything from basic function to the essentials qualities that make you, you. So, when it comes to delivering radiation to a target in or near the brain, sub-millimeters matter. Precisely delivering the prescribed radiation dose to the target is essential for optimizing long-term cancer control — and minimizing the risk of potential side effects that can impact short- and long-term quality of life.
CyberKnife SRS treatment is a form of hypofractionated radiation therapy. Compared to traditional radiation therapy treatments — commonly called conventional fractionation, which uses a relatively lower dose of radiation, delivered in a dozen or more sessions across several weeks — hypofractionation entails delivering a higher dose per session (called a fraction) across fewer total sessions. Hypofractionated SRS treatment for brain cancer can be completed in as little as 1-5 sessions in 1-2 weeks. Hypofractionated radiation therapy, such as brain SRS, has been proven to deliver clinical outcomes as good as conventional fractionation — while dramatically reducing both the number of treatments and the total cost of care for both patients and payers.
Despite the high dose rate associated with SRS, multiple studies have validated that the risk of common cognitive side effects is actually lower with CyberKnife SRS than with traditional radiation13. The ability to deliver precise doses of radiation enables clinicians to decrease exposure to surrounding healthy brain tissue, which can help minimize negative side effects such as fatigue and memory and concentration impairments. The majority of patients can continue normal activity during and immediately following treatment. Nonetheless, side effects from radiosurgery or SRS may occur during or after treatment and can be severe.
Extensive clinical research demonstrates that brain SRS with the CyberKnife System delivers excellent short- and long-term outcomes:
- CyberKnife SRS has been proven safe and effective for a broad range of neurological indications including brain3, 10, 14and spinal tumors4, 5, 15, meningioma6, acoustic neuroma7, 8, 9, pituitary adenomas16, vascular malformations6, and functional disorders17.
- In a clinical study of 133 patients treated for tumor metastases to the brain presenting with clinical symptoms such as headaches and seizures, 90 percent of patients either stabilized or improved performance status following treatment with the CyberKnife System14.
- In a clinical study of 333 patients using the CyberKnife System to treat tumor metastases to the brain, more than 85 percent of evaluable patients achieved local tumor control at two years post treatment14. That is, the tumor either decreased in size or stopped growing.
- A clinical study of 199 patients whose lesions were unsuitable for treatment with surgery and/or a portion of the lesion remained after surgery found that more than 92 percent of patients either experienced stabilization or a significant improvement of their symptoms following treatment with the CyberKnife System6.
Because it can precisely target tumors, the CyberKnife System may provide a safe and effective radiation treatment option even for some previously irradiated patients.
Patients treated with the CyberKnife System are excellent candidates for re-treatment, in the event of recurrence.
In the event of a recurrence, it is generally not recommended that patients undergo a second course of whole-brain radiation. Because the precise targeting of the CyberKnife System significantly reduces irradiation of surrounding healthy tissues, CyberKnife may provide a safe radiation treatment option for some previously irradiated patients.
- Patients who have previously received whole-brain radiation may be able to receive additional CyberKnife SRS treatments.
- Patients previously treated with CyberKnife radiosurgery (SRS) can be safely and effectively treated with additional courses of SRS — thereby delaying or completely avoiding whole-brain radiation10.
As of January 2020, SRS treatment for brain tumors is covered by Medicare in all 50 states and the District of Columbia in the United States. In addition, many private insurance payers cover SRS treatment for brain tumors. It is always best to check your insurance policy and if applicable, be sure to review your employee contract to determine if your insurance coverage benefits are limited. The CyberKnife Center that you have chosen to provide your treatment should be able answer insurance related coverage questions.
Not every patient’s brain cancer is effectively treated with SBRT. Talk to your physician about your best options and come to a joint decision. If whole-brain irradiation is recommended or if a glioma or a pituitary adenoma treatment as example is required, Accuray’s Radixact® or TomoTherapy® System may be a good option: Radixact and the TomoTherapy Systems leverage CT-image guidance to ensure highly conformal dose delivery to the tumor with each treatment.