CyberKnife Spine Cancer Treatment

SPINE CANCER
The CyberKnife® Robotic Radiosurgery System was cleared by the U.S. Food and Drug Administration in 2001 to treat tumors anywhere in the body, including the spine. Despite its name, the CyberKnife System is not a surgical procedure. In fact, there is no cutting involved. Instead, the CyberKnife System delivers high doses of radiation directly to spine tumors. The CyberKnife System offers patients who cannot undergo spine cancer surgery due to their poor medical condition, or who refuse surgery, a minimally invasive alternative treatment for spine cancer. CyberKnife spine cancer treatments are typically performed on an outpatient basis over a period of one to five days, requiring no overnight hospital stays. Most patients experience minimal to no side effects with a quick recovery time.

What is Spine Cancer?
How is It Detected?
How is It Treated?
How Does the CyberKnife Treat Spine Cancer?
References

Spine Video

Click image to view video

What is Spine Cancer?
Spine cancer is an abnormal growth of cells in or around the spinal cord resulting in a tumor. If the abnormal cells originated from cells in the tissues of the spine, the resulting collection of cells is called a primary spine tumor. If the abnormal cells originated in another part of the body, such as the lung or breast, and were carried to the spine by the blood or other bodily fluid, then it is considered a metastatic spine tumor. More than 18,000 cases of primary spine tumors and more than 162,000 spine metastases are diagnosed in United States each year¹.Spinal metastases can occur in up to 40 percent of cancer patients².
Primary Spine Tumors
Primary spine tumors are relatively rare types of tumors that originate in or around the spine itself. They can either be benign (non-cancerous) or malignant (cancerous). Benign tumors include meningiomas, neurofibromas and schwannoma, while malignant ones include astrocytomas and ependymomas¹.

Metastatic Spine Tumors
Metastatic tumors can spread to the spine through the bloodstream, along nerves or within the fluid that surrounds the spinal cord and brain. These cells most commonly originate from tumors within the lung, breast, skin and colon, and are deposited in the spine, eventually growing into a tumor or tumors³.
Both primary and metastatic spine tumors are very dangerous because they can compress the spinal cord and/or destroy the bone and surrounding tissue in the spine. These tumors cause patients to experience pain, gait and posture problems, and other neurological issues. As these tumors grow larger, patients can become paralyzed if the tumor cuts the spinal cord completely¹.

How is Spine Cancer Detected?
Spine tumors are usually detected because a patient will have symptoms, such as back pain, difficulty walking, sexual dysfunction and limb weakness. Patients often experience pain that either is in the spine itself or radiates from the nerves in the spine. Because none of these symptoms are unique to spine tumors, the diagnosis must be confirmed through a combination of a physical examination and imaging, such as magnetic resonance imaging (MRI) and computed tomography (CT) scans. Once a spine tumor has been diagnosed, more tests may be needed to identify the specific type of tumor and determine the proper treatment for the patient.

How is Spine Cancer Treated?
Generally, treatment of spine tumors requires a multidisciplinary approach. Often a combination of treatments – such as surgery, radiation therapy and/or chemotherapy – is most effective in fighting the disease.
Surgery:
For solitary tumors that are not embedded near the spinal cord, surgery is commonly used. Surgery may be followed by radiation therapy to eliminate any microscopic traces of the tumor that remain. If the vertebrae of the spine are eroded by the tumor, stabilization of the spine may be required. Stabilization can be accomplished through use of metal hardware or by injecting bone cement into the affected vertebra. When the tumor is impinging on the spinal cord, the neurosurgeon may cut away the tumor to relieve the pressure in a special procedure called spinal cord decompression².
Radiation Therapy:
If the patient suffers from multiple tumors, which is often the case with metastatic spine cancer, he or she will typically undergo radiation therapy. Radiation therapy uses low doses of radiation to treat the tumor, in order to minimize damage to healthy tissues, including the spinal cord and nerves. Conventional radiation therapy is generally given in 20 to 40 treatment sessions over four to six weeks⁴.
Chemotherapy:
Chemotherapy medication is delivered orally or through an IV. It affects both normal tissue and the cancer cells, so patients may experience side effects, such as severe nausea and vomiting, infections, fatigue and weight loss. Chemotherapy often is given to a patient in combination with other types of spine cancer treatment.
Radiosurgery:
Radiosurgery devices, such as the CyberKnife Robotic Radiosurgery System, offer patients a new option for spine cancer treatment⁵. Unlike conventional radiation therapy, during which low doses of radiation are delivered over weeks and months, the CyberKnife System can treat a tumor in one to five days by delivering a high dose of radiation with extreme accuracy.

How Does The CyberKnife® Treat Spine Cancer?
The CyberKnife System offers patients a new option for spine cancer treatment5. Unlike conventional radiation therapy, during which low doses of radiation are delivered over weeks and months, the CyberKnife System can treat a tumor in one to five days by delivering a high dose of radiation with extreme accuracy.
Spine tumors present a treatment challenge because they move as the patient breathes. Conventional radiation therapy cannot account for this movement, so surrounding healthy tissue is damaged by the radiation. The CyberKnife System is able to achieve a high level of accuracy completely non-invasively – without the use of body frames or implanted fiducial markers. It can pinpoint a tumor’s exact location in real time throughout treatment⁷.
The CyberKnife System allows the patient to breathe normally while on the treatment table, enabling the doctor to zero in on the moving tumor and focus hundreds of radiation beams from different angles, all of which intersect at the tumor. Using this method, the CyberKnife System is able to deliver a high dose of radiation to the tumor while avoiding damage to the surrounding sensitive spinal cord tissue and other critical structures. As a result, radiation is delivered more accurately and treatments can be performed in a shorter period of time⁶.
Clinicians using the CyberKnife System have pioneered the treatment of spine tumors with radiosurgery and it was more than 10 years ago that the first CyberKnife patient was treated for spine cancer5
CyberKnife treatments involve a team approach, in which several specialists participate:
a Neurosurgeon
an Orthopedic Surgeon
a Radiation Oncologist
a Medical Physicist
a Radiation Therapist
Medical Support Staff
Once the team is in place, preparation for the CyberKnife treatment will begin. Generally there are three steps involved:
Set up and imaging
Treatment planning
CyberKnife treatment
During set-up and imaging, the patient may be fitted for a custom body cradle, which is designed to help keep the patient more comfortable and ensures he or she is in the same position for both imaging and treatment.
If the tumor is in the upper cervical region, the patient also may be custom-fitted with a mesh face mask. Both the cradle and face mask are painless and completely non-invasive.
While laying in the body cradle and/or wearing the face mask, the patient will undergo a computed tomography (CT) scan. This scan data will be used by the CyberKnife team to determine the exact size, shape and location of the tumor. A magnetic resonance image (MRI) or some other type of imaging study also may be needed to fully visualize the tumor and nearby anatomy. Once the imaging is done, the body cradle or face mask will be stored for use during treatment.
Treatment planning is then performed by a medical physicist in conjunction with the treatment team. The patient will not need to be present at this time. During treatment planning, all CT, MRI and other scan data will be downloaded into the CyberKnife System’s treatment planning software to develop a customized treatment plan. The medical team will determine the size of the area being targeted by radiation and the dosage, as well as identifying critical structures – such as the spine or vital organs – where radiation should be minimized. The CyberKnife System calculates the optimal radiation delivery plan to treat the tumor. The treatment plan will take full advantage of the CyberKnife System’s maneuverability, allowing for extremely accurate delivery of radiation.
After the plan is developed, the patient will return to the CyberKnife center for treatment. The doctors may choose to deliver the treatment in one session, or stage it over several days. Typically, treatments are completed in one to five days.
For most patients, the CyberKnife treatment is a completely pain-free experience. Patients dress comfortably in their own clothes and, depending on the treatment center, they may be allowed to bring music to listen to during the treatment. Patients also may want to bring something to read while they wait, and have a friend or family member with them to provide support before and after treatment.
If lying on one’s back is painful, the doctor may instruct the patient to take pain medication prior to the CyberKnife treatment in order to minimize any discomfort.
After arriving at the CyberKnife center, the patient will be escorted into the treatment room, placed in the body cradle and/or face mask and then positioned on the treatment couch. The patient will be monitored through closed circuit television and be able to communicate with the treatment team at all times.
When treatment begins, the CyberKnife System will use X-rays to place the patient into the proper position and pinpoint the location of the patient’s tumor. The CyberKnife System’s computer-controlled robot will move the radiation source to multiple locations around the patient as they lie still on the table. Throughout the treatment, more digital images of the spine will be captured by the image guidance system in order to verify the tumor location. If the patient moves slightly, the change is detected by the imaging system, which automatically adjusts the robotic arm before delivering the radiation. By adjusting in this manner, the radiation beam can accurately target the tumor throughout the entire treatment process and minimize damage to healthy tissue.
Nothing will be required of the patient during the treatment, except to relax and lie as still as possible. In fact, patients often sleep through the treatment.
There are generally only minimal side effects from CyberKnife treatments. Occasionally patients report mild, temporary nausea, particularly if the lower abdomen is undergoing treatment. Prior to treatment, the doctor will discuss with the patient all possible side effects they may experience. The doctor also may prescribe medication designed to control any side effects should they occur.
After completing the CyberKnife treatment, patients should schedule and attend all follow-up appointments. Patients must keep in mind that the tumor will not suddenly disappear. In fact it could take several months, or longer, to determine the effectiveness of the CyberKnife treatment. Response to treatment varies from patient to patient. Clinical experience has shown that most patients respond very well to CyberKnife treatments. By routinely evaluating the symptoms and undergoing post-operative MRIs, the doctor can chart the patient’s post-treatment progress.

Prostate

Lung

Brain

Spine

Liver

Pancreas

Other

References

1. Simmons, E.D. and Y. Zheng, Vertebral tumors: surgical versus nonsurgical treatment. Clin Orthop Relat Res, 2006. 443: p. 233-47.
2. Klimo P.Jr., S.M.H., Surgical Management of Spinal Metastases. The Oncologist, 2004. 9: p. 1880196.
3. Mut, M., D. Schiff, and M.E. Shaffrey, Metastasis to nervous system: spinal epidural and intramedullary metastases. J Neurooncol, 2005. 75(1): p. 43-56.
4. van den Hout, W.B., et al., Single- versus multiple-fraction radiotherapy in patients with painful bone metastases: cost-utility analysis based on a randomized trial. J Natl Cancer Inst, 2003. 95(3): p. 222-9.
5. Ryu, S.I., et al., Image-guided hypo-fractionated stereotactic radiosurgery to spinal lesions. Neurosurgery, 2001. 49(4): p. 838-46.
6. Muacevic, A., et al., Technical description, phantom accuracy, and clinical feasibility for single-session lung radiosurgery using robotic image-guided real-time respiratory tumor tracking. Technol Cancer Res Treat, 2007. 6(4): p. 321-8.
7. Ho, A.K., et al., A study of the accuracy of cyberknife spinal radiosurgery using skeletal structure tracking. Neurosurgery, 2007. 60(2 Suppl 1): p. ONS147-56; discussion ONS156.