CyberKnife® Radiosurgery for Pancreatic Lesions
Brief Overview:
Pancreatic cancer remains one of most challenging of all human malignancies, with surgical removal representing the only realistic chance for a cure. Even with surgical removal of the pancreatic tumor (Whipple procedure), cure of this cancer is the exception rather than the rule (1-3). The Whipple procedure (also known as radical pancreaticoduodenectomy) is a significant operation, with potential serious complications, including a small incidence of operative mortality. Additional therapies in combination with surgery, including both chemotherapy and combined chemotherapy-radiotherapy, appear to have improved the cure rate compared with surgery alone, with both preoperative and postoperative regimens described, neither approach clearly proven better than the other (4-8).

With radiotherapy, it is very difficult to deliver a potentially curative radiation dose to the pancreatic tumor volume, due to its typical close approximation to the stomach, small intestine, large intestine, liver, kidneys and spinal cord. With modern techniques such as intensity modulated radiotherapy (IMRT), upper abdominal tolerance to radiation appears improved, due to improved conformality of the high dose volume (14,15).

To make matters worse, a majority of pancreatic cancer patients are not even eligible for attempted surgical cure, due to local tumor invasion of adjacent vital structures such as vital blood vessels, or due to the existence of metastatic disease (spread of their cancer to other organs, such as the liver) (1-3). Nonsurgical approaches have also been used in unresectable pancreatic cancer, including radiotherapy, chemotherapy and combined radiotherapy-chemotherapy (9-14).  While life extension may be achieved with these approaches, there is very little, if any curative potential. Combined chemo-radiotherapy has been proven superior to radiation therapy alone in a randomized trial (11,12) though it is not clearly established that chemotherapy-radiotherapy is superior to chemotherapy alone (13).

There is still no published evidence of added survival benefit with IMRT, though the 69% 1 year survival rate in inoperable patients reported with the combination of IMRT and capecitabine (chemotherapy) appears superior to historical results, and the toxicity in this study was within acceptable limits (15).