Colorado Cyberknife

Cyberknife VSI Robotic Radiosurgery Treatment for Pancreatic Cancer

Stereotactic radiosurgery is a technique for delivering highly accurate, very large focused doses of radiation to tumors while minimally irradiating surrounding normal tissues. Radiation oncologists and neurosurgeons have been using this technique for almost two decades to effectively treat brain tumors. Improvements in targeting and radiation delivery now allow physicians to treat tumors outside the brain with radiosurgery for the first time. In particular, some radiation oncologists and surgeons are using CyberKnife radiosurgery to treat abdominal tumors. The aggressive doses of focused radiation utilized in pancreatic cases are similar to those that have been shown in prior studies to be very effective in destroying brain and spinal tumors. Multi-institutional clinical studies are presently underway to test the effectiveness of CyberKnife radiosurgery for treating localized, non-metastatic pancreatic cancer. Preliminary studies conducted at Stanford University Medical Center in patients with relatively advanced disease suggested that CyberKnife radiosurgery was both well tolerated and that treatment was associated with some clinical benefit.

What is pancreatic cancer?

Pancreatic cancer is an abnormal growth of malignant cells that originates from one of the many parts of the pancreas. The pancreas, a 6-inch organ located behind the stomach in the upper abdomen, produces both enzymes for digesting food and hormones, such as insulin, that regulate multiple bodily functions.
Because the pancreas is composed of a variety of cell types, there are many forms of pancreatic cancer. Unfortunately the most common pancreatic cancer, adenocarcinoma (which arises from the pancreatic duct and gland cells), is also the most difficult to treat. Pancreatic adenocarcinoma, which comprises approximately 95% of all pancreatic cancer, is the main reason there are almost as many deaths from pancreatic cancer each year as there are newly diagnosed cases (about 30,000 each year). The survival rate is generally better for the 5% of pancreatic cancers that are not adenocarcinomas.

There are basically two reasons why pancreatic cancer is so difficult to cure. First, it grows silently with very few symptoms until the tumor is quite advanced or has already spread outside of the pancreas. Secondly, this type of cancer generally does not respond well to many of the available treatments.

What are the symptoms associated with pancreatic cancer?

The earliest signs of pancreatic cancer are often so vague and mild that they are overlooked. The most common early symptoms typically include loss of appetite with mild weight loss and a vague, mild discomfort in the upper abdomen or occasionally in the middle-back area (the pancreas is positioned in the back of the abdomen directly over the spine). Because there are so many other potential, and relatively minor, explanations for this spectrum of symptoms, the earliest signs of pancreatic cancer are often ignored. However, as the cancer progresses, it causes increasingly more noticeable symptoms, such as yellow jaundice (often with little or no associated pain), which stems from the obstruction of the main duct that drains the liver’s bile. As the tumor continues to grow, other digestive problems such as bloating or nausea from obstruction of the stomach are also common. Although pancreatic cancer is difficult to detect on physical exam in initial stages, firmness is some times felt in the upper middle abdomen late in the course of the disease.

How is pancreatic cancer diagnosed?

Despite ongoing research to diagnose pancreatic cancer earlier, no effective blood test has been developed to screen for this cancer. Although the presence of blood tumor marker “CA 19-9″ may sometimes be used to help confirm a diagnosis of pancreatic cancer or follow a patient after treatment, this relatively simple test has not proven effective as a screening tool. Instead, radiologic tests such as an abdominal ultrasound or CAT scans are used to arrive at a presumptive diagnosis of pancreatic tumor. A definitive diagnosis of pancreatic cancer is most frequently established through subsequent endoscopy and appropriate biopsies. During endoscopy, a lighted fiber-optic tube is passed through a patient’s mouth and into the stomach and duodenum (upper intestine). Using an ultrasound probe, it is sometimes possible to biopsy the tumor under direct visualization. The endoscope allows a specially trained doctor to visually inspect this portion of the gastrointestinal tract as w ell as the region in and around the junction with the pancreatic duct. In those patients who suffer from jaundice, a special tube called a stent will oftentimes be inserted into the bile duct at the time of endoscopy to open up this passageway and thereby permit more normal drainage of bile. It is not unusual to use all three of these tests (CAT scan, ultrasound, and endoscopy) when working up suspicious symptoms. Another frequently used method of diagnosis is to pass a needle into the tumor using a CAT scan to direct the placement of the needle. A small sample of the tumor is removed by this method and visualized under a microscope to confirm the presence of a tumor and to identify the type of tumor.

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