CyberKnife Pancreas Cancer Treatment

PANCREAS CANCER
The CyberKnife® Robotic Radiosurgery System was cleared by the FDA in 2001 to treat tumors anywhere in the body, including the pancreas. 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 pancreatic tumors. The CyberKnife System offers patients who cannot undergo pancreatic cancer surgery due to their poor medical condition, or who refuse surgery, a minimally invasive alternative treatment for pancreatic cancer. CyberKnife pancreatic cancer treatments are typically performed on an outpatient basis in one to five days, requiring no overnight hospital stays. Most patients experience minimal to no side effects with a quick recovery time.

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

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What is Pancreatic Cancer?
Pancreatic cancer is the abnormal growth of cells in the pancreas that results in a tumor. If the abnormal cells originated in the pancreas, it is considered a primary pancreatic tumor. In this case, most tumors begin in the ducts of the pancreas and are called adenocarcinomas. If the abnormal cells originated in the pancreas and were carried to other parts of the body through blood or other bodily fluids, then it is considered a metastatic pancreatic tumor.
It is estimated that 37,000 new cases of pancreatic cancer will occur in the United States in 2008, and an estimated 34,000 people will die from this disease in 2008 alone.¹ Over 200,000 cases of pancreatic cancer occur annually throughout the world.² Left untreated, median survival is about 4 months; although only 2% of cancers in the United States are pancreatic, it is the 4th leading killer.³ Its low rate of cure reflects, in part, the fact that a large proportion of pancreatic cancers are advanced when they are first detected.

How is Pancreatic Cancer Detected?
In its early stages, pancreatic cancer usually does not cause symptoms. When symptoms occur, the cancer is often advanced. Patients may experience jaundice, pain and weight loss. A physical exam and blood tests may be used in the initial diagnosis, but blood tests alone cannot confirm pancreatic cancer. Computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, ultrasound and positron emission tomography-CT (PET-CT) scans may be used to aid in the diagnosis. A biopsy may be needed to determine the nature of the cancer cells in patients who are not surgical candidates. Doctors then determine the “stage” – or extent of the disease – by establishing how big the tumor is and how much it has spread.³

How is Pancreatic Cancer Treated?
Treatment of pancreatic cancer depends on its type and the stage. Early-stage pancreatic cancer may be removed surgically with the goal of curing the patient. The most common surgery is called the Whipple Procedure. This is the surgical resection for a tumor in the head of the pancreas and entails the removal of a portion of the pancreas, the gall bladder, the duodenum (small intestine) and part of the stomach. Generally, surgical resection is only possible in 20 percent of pancreatic cancer cases.⁴ In those cases, surgical resection has a median survival of 15 to 25 months and a 15 percent to 20 percent long-term survival rate.^4-6 Chemotherapy, radiation therapy, and/or radiosurgery can be used to treat patients whose disease is more advanced. In these cases, chemotherapy combined with concurrent standard radiation therapy typically results in a median survival of eight to 12 months.⁷ At the end stages of the disease, medicine, limited surgeries and other therapies may be used to treat the pain, obstruction of the bile duct and hormonal consequences of pancreatic cancer.³ Radiation therapy alone, or in conjunction with chemotherapy, has been shown to provide some pain control at this stage, with 35 percent to 65 percent effectiveness.⁶

How Does The CyberKnife® Treat Pancreas Cancer?
The CyberKnife System has been used to treat pancreatic cancer in patients who are poor surgical candidates, those who refuse surgery and in patients for whom surgery or other treatments have failed. Two clinical studies from Stanford University^8-9 have shown the growth of pancreatic tumors in patients with advanced disease has been controlled by CyberKnife radiosurgery. One study estimated the six-month survival at 80 percent and the estimated one-year survival at 15 percent.⁹ In another preliminary study, CyberKnife treatment was shown to provide pain control in 85 percent of the treated patients.¹⁰
Treating tumors in and near the pancreas with radiation is challenging because those tumors move as you breathe, making it difficult to target them accurately with radiation. As a result, the tumor may not receive enough radiation and healthy tissue near the tumor may be damaged. With other kinds of radiation therapy – often referred to as conventional, external-beam, or intensity-modulated radiotherapy – the total radiation dose is divided up into smaller doses delivered over 25 to 40 sessions in order to minimize damage to surrounding healthy tissue. CyberKnife radiosurgery is intended to destroy, or ablate, the tumor tissue with high doses delivered in one to five sessions. To do that safely requires a highly accurate system that detects the movement of the tumor throughout treatment sessions and delivers the radiation with pinpoint precision.
Working in conjunction with the CyberKnife System is the Synchrony® Respiratory Tracking System, which enables the radiation beam to track tumor movement in real time and allows patients to breathe normally during their treatment sessions. With the CyberKnife System, doctors can zero in on a moving target – the pancreatic tumor – and irradiate it without harming the healthy surrounding tissue. As a result, the CyberKnife treatment is more comfortable for patients, radiation is delivered more accurately and treatments can be completed in one to five sessions.
Pancreatic cancer treatment with the CyberKnife System involves a team approach, in which several specialists participate. A team may include:
a Surgeon
a Radiation Oncologist
a Medical Physicist
a Radiation Therapists
Medical Support Staff
Once the team is in place, the patient will begin preparation for CyberKnife treatment. The CyberKnife treatment generally involves four steps:
Fiducial placement
Set-up and imaging
Treatment planning
CyberKnife treatment
During the first step of the treatment process, the patient is scheduled for a short outpatient procedure in which three to five fiducials – tiny gold seeds each about the size of a grain of rice – are inserted into the pancreatic tumor using CT guidance. The CyberKnife System uses those markers as reference points to identify the exact location of the pancreatic tumor during treatment. Once fiducials are implanted, the patient must wait approximately one week before CyberKnife treatment planning can begin to ensure that fiducial movement has stabilized.
During set-up and imaging, the patient will be fitted for a custom body cradle, which is designed to help keep him or her more comfortable and ensures consistent positioning for both imaging and treatment. The patient also will be fitted with a special Synchrony vest, which is worn during CyberKnife treatment and enables the robot to correlate chest motion and breathing patterns with the tumor position. The data generated with the vest allows the CyberKnife robot to precisely follow the tumor’s motion as it delivers each beam of radiation, ensuring safe and accurate radiation delivery.
While wearing the vest, the patient will undergo a series of CT imaging studies, which will enable the CyberKnife team to determine the exact size, shape and location of the tumor. An MRI scan also may be necessary to fully visualize the tumor, pancreas and nearby anatomy. Once the imaging is done, the body cradle will be stored for the remaining CyberKnife treatments.
Next a treatment plan will be specifically designed by a medical physicist in conjunction with the patient’s doctors. The patient does not need to be present at this time. During treatment planning, the CT and MRI scan data is downloaded into the CyberKnife System’s software. The medical team determines the size of the area being targeted by radiation and the radiation dosage, as well as identifying critical structures where radiation should be minimized. Each patient’s unique treatment plan will take full advantage of the CyberKnife System’s extreme maneuverability, allowing for a safe and accurate pancreas cancer treatment.
After a treatment plan is developed, the patient returns to the CyberKnife center for treatment. Pancreatic cancer treatment is usually delivered in four to five sessions, which are typically completed within one week.
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.
When it is time for treatment, the patient will be asked to put on their Synchrony vest and lie on their custom body cradle. The radiation therapist will ensure the vest is properly adjusted and that the patient is positioned correctly on the treatment couch.
As treatment begins, the location of the pancreas tumor will be tracked and detected continually as the patient breathes normally. The medical team will be watching every step of the way as the CyberKnife System tracks the patient’s pancreas tumor as it moves, and safely and precisely delivers radiation to it.
The CyberKnife System’s computer-controlled robot will move around the patient’s body to various locations from which it will deliver radiation. At each position, the robot will stop. Then, special software will determine precisely where the radiation should be delivered by correlating the location of the tumor using digital images of the fiducials and information from the Synchrony vest. The CyberKnife’s robotic arm will adjust the radiation source automatically, to follow the pancreas tumor as it moves. Nothing will be required of the patient during treatment, except to relax and lie as still as possible.

Once treatment is complete, most patients quickly return to their daily routines with little interruption to their normal activities. If treatment is being delivered in stages, the patient will need to return for additional treatments over the next several days as determined by their doctors. Early results indicate that patients tolerate the CyberKnife procedure well, and it does not impair pancreas function. Doctors will discuss all possible side effects prior to treatment. In addition, doctors may prescribe medication to control any side effects, should they occur.
After completing CyberKnife radiosurgery treatment, it is important for the patient to schedule and attend any follow-up appointments. The patient should be aware that his or her tumor will not suddenly disappear. Response to pancreas cancer treatment varies from patient to patient. It could take several months or longer to determine the effectiveness of the CyberKnife treatment. Doctors will monitor the outcome in the months and years following a patient’s treatment using imaging studies and evaluating his or her symptoms.

Prostate

Lung

Brain

Spine

Liver

Pancreas

Other

References

1. American Cancer Society, “Cancer Facts & Figures, 2008”.
2. Ferlay J, Shin HR, Bray F, Forman D, Mathers C and Parkin DM. GLOBOCAN 2008, Cancer Incidence and Mortality Worldwide: IARC CancerBase No. 10 [Internet]. Lyon, France: International Agency for Research on Cancer; 2010. Available from: http://globocan.iarc.fr
3. Freelove R, Walling AD: Pancreatic cancer: diagnosis and management, Am Fam Physician. 2006;73:485-492.
4. Perman M, Bellairs EE, Wu X, and Schwade JG. Cancer of the Pancreas with Special Reference to Epidemiology & Radiosurgery. In Mould, F, ed. Robotic Radiosurgery Volume 1; The CyberKnife Society Press, 301-313, 2007.
5. Klinkenbijl JH, Jeekel J, Sahmoud T, et al. Adjuvant radiotherapy and 5-fluorouracil after curative resection of cancer of the pancreas and periampullary region: phase III trial of the EORTC gastrointestinal tract cancer cooperative group. Ann Surg 230:776-782, 1999.
6. Yeo CJ, Cameron JL, Lillemoe KD, et al. Pancreaticoduodenectomy for cancer of the head of the pancreas. 201 patients, Ann Surg 221:721-731, 1995.
7. Mawdsley S, Hall M, Glynne-Jones R. Locally advanced pancreatic cancer treated with radiation and 5-fluorouracil. Clin Oncol (R Coll Radiol) 14:308-312, 2002.
8. Koong AC, Le QT, Ho A, et al. Phase I study of stereotactic radiosurgery in patients with locally advanced pancreatic cancer, Int J Radiat Oncol Biol Phys, 58: 1017-21, 2004.
9. Koong AC, Christofferson E, Le QT, et al. Phase II study to assess the efficacy of conventionally fractionated radiotherapy followed by a stereotactic radiosurgery boost in patients with locally advanced pancreatic cancer, Int J Radiat Oncol Biol Phys, 63: 320-3, 2005.
10. Hoffelt, C. and Didolkar, M. Stereotactic Radiosurgery for Unresectable Adenocarcinoma of the Pancreas: Initial Experience at Sinai Hospital of Baltimore. In: Urschel HC, ed. Robotic Radiosurgery: Treating Tumors that Move with Respiration. Heidelbert: Springer-Verlag, 177-192, 2007.