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The pancreas is located in the retroperitoneum, an area near the center of the body and close to the back. Some pancreatic cells produce digestive enzymes that empty into the duodenum from the pancreatic duct, which runs through the pancreas. The pancreas also has cells that produce hormones like insulin. Both types of cells can develop into cancer, but cancer of the cells that produce the digestive enzymes is more aggressive, and has been the most difficult cancer to treat. Pancreatic cancer develops in about 28,000 people in the United States per year.
Cancer of the pancreas frequently does not cause symptoms until it is advanced. CT scan, angiogram and even MRI will frequently miss tumors less than two centimeters in diameter (more than one inch). EUS can find tumors that are smaller than three millimeters (less than a quarter of an inch).
Surgery for pancreatic cancer has never been proven to extend life; it can, however, help manage symptoms for a while. But now, there are many other ways to improve symptoms without surgery. For example, jaundice, which results from a blockage of pancreatic ducts, can be treated by placing stents into the bile duct with an endoscope to "bypass" the blockage. Also, recent reports indicate that treating of pancreatic cancer with chemotherapy and radiotherapy to shrink tumors before surgery, results in much longer average survival (about two years) than when surgery is done first (about one year).
Role of EUS
The pancreas can also develop a mass due to inflammation caused by irritation from a stone, alcohol or other toxin. Determining whether a mass is due to inflammation or to cancer can be nearly impossible without EUS. EUS alone has been shown to be accurate in determining if cancer is present in about 90% of cases. With EUS, biopsies of tumors can also be obtained if needed to confirm the diagnosis. Although biopsies of pancreatic masses are often performed using CT scan guidance, the diagnostic accuracy of biopsies obtained this way is less than 50% at most centers, especially for smaller tumors that may be surgically removable. Non-operative diagnosis and staging of pancreatic disease with EUS has therefore become critical to determining the correct treatment plan.
Cysts can also develop in the pancreas. These cysts are usually not malignant, but sometimes it is difficult to tell. Again, EUS can be very helpful. Small details of the cyst wall, the surrounding tissue and the inside of the cyst that can be seen only with EUS can help determine whether the cyst is malignant. Malignant cystic tumors of the pancreas should be removed if possible. Patients with cystic cancer tend to live longer when surgery is performed, and may even be cured. If the cyst does not look cancerous, it can be watched closely. Most of the time custs will go away on their own, especially if they are caused by inflammation. If they do not go away, and they do not develop suspicious changes, they do not require any treatment unless they start to cause symptoms such as pain. If symptoms persist, the cyst may be drained, a procedure that can usually be done open surgery.
Stones, alcohol and other toxins or drugs can be the cause of a cyst. Removing the irritant usually causes the inflammation and the cyst to go away. Sometimes, however, the inflammation leaves scar tissue or does not clear up. This residual scarring can remain dormant, or it can cause pain that may be quite severe. Less often, it may cause chronic diarrhea.
Chronic Pancreatitis: Mild
Once chronic or recurrent episodes of upper abdominal pain are found to be related to chronic pancreatitis, various treatments from medication to surgery are available. Treatment is successful more often than not, but finding a treatment that works can be very frustrating and difficult for the patient and the doctor.Chronic scarring or fibrosis of the pancreas, chronic pancreatitis, can be very difficult to diagnose, especially if there is no obvious cause such as chronic alcohol abuse. EUS has recently been shown to be the sensitive best way to find subtle changes in the pancreas that occur in mild chronic pancreatitis. Even though chronic pancreatitis may be classified as mild, it can still cause significant pain. In many cases, this type of pancreatitis is caused by crystals in the bile. These crystals can only be found by analyzing bile during a procedure called an ERCP, for endoscopic retrograde cholangiopancreatography. ERCP involves placing catheters into the bile and pancreatic ducts and injecting dye to visualize the ducts with x-ray. ERCP is the second best way to diagnose mild chronic pancreatitis. However, it has at least a 5% complication rate, even when performed by doctors with the most experience.
Chronic Pancreatitis: Moderate or Severe
When chronic pancreatitis is classified as moderate or severe, it is much easier to diagnose with a variety of tests, including EUS. Sometimes the cause of symptoms or pain is spasm of the sphincters of the area where the bile and pancreatic ducts join and empty into the duodenum. A disorder called sphincter of Oddi dysfunction (SOD). Diagnosis of SOD can be made by measuring pressures at the ampulla during ERCP. If pressures are high, sphincterotomy is usually effective in treating symptoms in about 90% of cases. If pressures are not high, sphincterotomy may work, but results are less consistent. Other tests, including EUS, may help determine which patients will respond to a sphincterotomy.
Treatment of symptoms are somewhat different than for mild chronic pancreatitis, and can include placement of stents during ERCP to "bypass" narrowed areas. Cutting the muscular sphincter (sphincterotomy) at the opening of the bile duct where it usually joins the opening of the pancreatic duct so that the two ducts are separated will many times be effective in treating the pain. If stones, sand or sludge is found in the bile duct, then symptoms usually resolve after a sphincterotomy.