CyberKnife Therapy for Pancreatic Cancer
» What is CyberKnife, and how can it be used to treat pancreatic cancer?
» When was CyberKnife approved to treat pancreatic tumors?
» What are CyberKnife's advantages for pancreas tumor treatment?
» How effective is CyberKnife in the treatment of pancreatic cancer?
» What is the process involved in receiving CyberKnife treatment for pancreatic cancer?
» What side effects may be associated with CyberKnife pancreatic cancer treatment?
Q. What is CyberKnife and how can it be used to treat pancreatic cancer?
CyberKnife is a robotically controlled radiation delivery machine. It was originally developed as a device to deliver Stereotactic Radiosurgery (SRS) for tumors of the brain. It is now approved to treat tumors anywhere in the body, including the pancreas. The procedure is called Stereotactic Body Radiotherapy (SBRT).
SBRT is a radiation treatment technique in which high doses of radiation are delivered using very precise beams that are targeted on the tumor. Using hundreds of focused beams of radiation, the CyberKnife delivers a high amount of ablative radiation therapy to precisely identified areas. The aim is to use such a high dose that the tumor is destroyed, while healthy tissue around it is spared. The radiation coming from the CyberKnife machine is the same type used in standard radiation machines.
Q. When was CyberKnife approved to treat pancreatic tumors?
CyberKnife was cleared by the U.S. Food & Drug Administration in 2001 to treat tumors anywhere in the body, including the pancreas.
Q. What are CyberKnife’s advantages for pancreas tumor treatment?
Many pancreas tumors are not surgically removable because they are located near critical blood vessels. Cyberknife SBRT is a safe, noninvasive way to treat these tumors. CyberKnife is also appropriate for patients who cannot undergo pancreas cancer surgery due to their weak medical condition, or who don’t want to undergo surgery. It is non-invasive, with no cutting involved.
A major challenge to treating pancreatic cancer with traditional radiation, and even other SBRT techniques, is that these tumors move in relation to the nearby critical structures as the patient breathes. For this reason, the tumor may not get enough radiation and healthy tissue may be damaged.
As a result, precision targeting of the tumor is critical. CyberKnife ensures this through a highly accurate system that detects and tracks tumor movement continuously during the treatment sessions and delivers the radiation with pinpoint accuracy. The Synchrony Respiratory Tracking System enables the radiation beam to detect tumor movement in real time and allows patients to breathe normally during treatments.
In other kinds of radiation, treatments are spread over 25 to 40 days with low doses given each day to minimize damage to healthy tissue. Since CyberKnife focuses on the tumor, delivers high doses or radiation, and spares the surrounding tissue, it destroys the tumor in one to five sessions.
Q. How effective is CyberKnife in the treatment of pancreatic cancer?
Two studies from Stanford University have shown that the growth of advanced pancreatic tumors has been controlled by CyberKnife treatment. One study put the six-month survival rate at 80 percent and estimated the one-year survival rate at 15 percent. The treatments also helped with pain control in 85 percent of patients.
Two influential studies from Beth Israel Deaconess Medical Center have shown that CyberKnife is a feasible and safe technique to treat inoperable pancreas cancer along with chemotherapy. Patients lived an average of 15 to 20 months, depending whether they received upfront chemotherapy. The three-treatment CyberKnife technique used by BIDMC is now followed around the world. These results achieved in three days with minimal side effects are comparable, if not superior to, outcomes associated with five to six weeks of standard radiation.
These results have been reproduced in further similar studies from Italy, Baltimore, Pittsburgh and Tampa.
Q. What is the process involved in receiving CyberKnife treatment for pancreatic cancer?
A team approach is used, involving a surgeon, radiation oncologist, interventional radiologist, a radiation therapist and other support staff. First, doctors identify the patients who may potentially benefit from this treatment, including those with inoperable cancers. Patients are then implanted with markers — tiny gold seeds — that serve as reference points for targeting the exact location of the tumor during treatment. Insertion is usually accomplished through endoscopic ultrasound. Occasionally, when tumors are deemed inoperable during surgery, gold markers are immediately placed while the patient is still in the operating room.
Patients must also be fitted with a special custom-molded body cradle that conforms to the body. This makes treatments more comfortable and ensures the body’s position is the same during every treatment. The patient also wears a special vest that allows the robot delivering the radiation to link up chest motion and breathing positions with the position of the tumor. The vest, along with constant imaging of the gold markers, generates data that allows the robot to closely follow the tumor’s motion as the radiation is delivered. While the patient is in the cradle, a CT scan is used to define the exact size, shape and location of the tumor.
Next, a treatment plan is designed to determine dosage to identify nearby areas where radiation must be minimal. The treatment is usually completed in three sessions of up to two hours each. During treatment, the robot moves around the patient’s body to deliver radiation in various locations. The robot stops at each location. As the treatment is being delivered, the robot essentially breathes along with the patient.
Q. What side effects may be associated with CyberKnife pancreatic cancer treatment?
Early results indicate that most pancreatic cancer patients tolerate CyberKnife treatments well and that their pancreas function is not affected. Common side effects may include fatigue and nausea. The treatment itself is pain-free. Patients are advised that their tumors will not immediately disappear, and that it could take months to determine the effectiveness of the treatments, including the stability of the treated tumor.