Pancreatic stenting for patients with obstructive pain secondary to a malignant pancreatic duct stricture is safe and effective, and should be considered a therapeutic option. Although pancreatic stenting does not seem to be effective for patients with chronic pain, it may be beneficial in those with obstructive type pains, pancreatic duct disruption, or smoldering pancreatitis. Fully covered metal stents may be an option, but data on their use are limited. Further studies, including prospective randomized studies comparing plastic and metal stents in these indications, are needed to further validate and confirm these results.
Key points
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Pancreatic stenting for patients with obstructive pain secondary to a malignant pancreatic duct stricture is safe and effective, and should be considered a therapeutic option.
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Although pancreatic stenting does not seem to be effective for patients with chronic pain, it may be beneficial in those with obstructive type pains, pancreatic duct disruption, or smoldering pancreatitis.
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Fully covered metal stents may be an option, but data on their use are limited.
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Further studies, including prospective randomized studies comparing plastic and metal stents in these indications, are needed.
Introduction
Pancreatic cancer affects 25,000 new people per year in the United States. It is the fifth most common cause of cancer-related death in the western world. It is estimated that only approximately 30% of patients diagnosed with pancreatic cancer have operable disease, and half of those cancers are deemed inoperable at the time of surgery. As a result, a large percentage of patients have inoperable disease at the time of diagnosis. Estimates show that fewer than 20% of the patients will survive 1 year after diagnosis, with an overall 5-year survival rate of less than 3%. Palliative management, therefore, is the primary concern. The most common symptoms that require treatment are obstructive jaundice, intestinal obstruction, and pain. Pain occurs in 85% of patients with advanced disease. Pain in pancreatic cancer is distressing and often poorly controlled. As a result, its management is an integral part of palliative care.
Introduction
Pancreatic cancer affects 25,000 new people per year in the United States. It is the fifth most common cause of cancer-related death in the western world. It is estimated that only approximately 30% of patients diagnosed with pancreatic cancer have operable disease, and half of those cancers are deemed inoperable at the time of surgery. As a result, a large percentage of patients have inoperable disease at the time of diagnosis. Estimates show that fewer than 20% of the patients will survive 1 year after diagnosis, with an overall 5-year survival rate of less than 3%. Palliative management, therefore, is the primary concern. The most common symptoms that require treatment are obstructive jaundice, intestinal obstruction, and pain. Pain occurs in 85% of patients with advanced disease. Pain in pancreatic cancer is distressing and often poorly controlled. As a result, its management is an integral part of palliative care.
Pain in pancreatic cancer
The mechanism of pain in pancreatic cancer is multifactorial. It may be the result of neoplastic infiltration of the neural tissue and peripancreatic tissue, or a result of obstruction of the main pancreatic duct, resulting in upstream dilation beyond a stricture with ductal hypertension, called obstructive pain . Classically pain caused by obstruction is postprandial. It is mainly located in the epigastrium or left hypochondrium, and occasionally radiates to the back, lasting 1 to 2 hours. This pain is similar to that which occurs in large duct chronic pancreatitis (CP). CP with pain is characterized by poor vascularity with severe periductal and arterial fibrosis. A main theory that has been tested in animal models and humans is that of increased pancreatic interstitial and ductal pressure causing a compartment syndrome, leading to a relative ischemia, as the source of pain. Normal pressure has been estimated to be between 7 and 15 mm Hg. Intraoperative measurements of ductal pressures range between 20 and 80 mm Hg in patients with CP. The thought is that continuous secretin excretion against a proximal obstruction from single or multiple strictures and/or calculi causes an increase in pressure, leading to decreased vascularity. The fibrosis that surrounds the chronically inflamed pancreas and its lobules plays a role in pancreatic tissue pressures. It does so by limiting the ability of pancreatic tissue to expand during periods of exocrine secretion, causing a situation similar to the compartment syndrome. The increase in ductal and interstitial pressure is associated with diminished basal pancreatic blood flow, as shown in experimental studies. This concept is further supported by the fact that decompression of a dilated pancreatic duct through stent insertion or, more often, surgical decompression (Puestow procedure) is frequently associated with pain relief. This theory also explains the “burnt out” phenomenon that intraductal hypertension decreases as the disease advances, because acinar tissue atrophies and pancreatic secretion does not increase on eating.
Ductal disruption
Another complication of pancreatic cancer is ductal disruption. This leads to numerous complications such as pancreatic ascites, fistula, pseudocyst, abscess formation, and necrosis. Pancreatic duct disruptions and associated fluid collections can be treated by surgical interventions such as: roux loop cystoenterostomy and resection of the tail of the pancreas often combined with splenectomy, percutaneous, or endoscopic procedures, which include cystgastrostomies or pancreatic stenting as described subsequently.
Smouldering pancreatitis
Pancreatic cancer produces obstructive pancreatitis upstream from a constricted portion of the pancreatic duct, acute pancreatitis is a less common manifestation of pancreatic cancer. Histologically pancreatic cancer is usually identified around the stenosis or stricture of the main duct.
Pain management
The management of pain remains a significant problem. Given that pain may be multifactorial, one single treatment is unlikely to result in complete resolution.
It is estimated that most patients have chronic, continuous, dull pain radiating to the back, and that this is the result of neoplastic infiltration. Celiac plexus block either endoscopically or percutaneously has been reported to have an 85% success rate. In the minority of patients (≈15%), pain is postprandial, located in the epigastrium and left upper quadrants, and usually associated with ductal abnormalities. Postprandial pain is defined as obstructive.
Endoscopic stenting of the main pancreatic duct may be considered to decompress obstructive-type pain that occurs after meal stimulation. Similar to the experience gained with large duct CP, inserting a stent will allow free pancreatic juice to flow into the duodenum with minimal obstruction.
Stenting the pancreatic duct can be technically challenging. These challenges may be from the presence of strictures that make wire advancement difficult or from the presence of complete or partial pancreatic divisum, which occurs in 15% to 20% of cases. If the patient is jaundiced, then simultaneous biliary sphincterotomy and stenting should be performed.
Technique of pancreatic stenting
Other than the reasons cited earlier, pancreatic duct stenting does not differ from biliary stenting. However, access, when challenging, may be gained with a hydrophilic wire, angled tip, or a smaller wire, such as the PathFinder or Roadrunner, 0.018-in diameters. The stricture can then be dilated with a Soehendra bougie (Wilson Cook, Winston-Salem, NC, USA) or wire-guided balloon dilation. After this, large-caliber stents should be placed for drainage. Stents larger than 5F are preferred to prevent stent occlusion and provide adequate pancreatic decompression. Plastic stents are thought to remain patent for up to 2 months, likely because of their small diameter. The Johlin-JPWS (Johlin Pancreatic Wedge Stent, Cook Endoscopy, Winston Salem, NC, USA ) has also been used. It is a plastic multiperforated stent with a tapered distal tip. In a comparative retrospective study addressing feasibility and efficacy of this stent, the Johlin stent had a significantly reduced rate of painful relapse as well as a lower rate of ductal obstruction compared to conventional plastic stents. Self-expanding metallic stents have been described in this indication, with the major advantage of longer patency, fewer repeat procedures, and better cost-effectiveness for patients expected to survive longer than 6 months ( Figs. 1–3 ). However, few reports have been published on their use in pancreatic strictures of malignant origin.
Related posts:
Advances in Pancreatic Endoscopy
Effective Endoscopic Management of Pancreatic Diseases
Role of Endoscopic Ultrasonography in the Diagnosis of Acute and Chronic Pancreatitis
Endoscopic Therapy for Acute Recurrent Pancreatitis
Endoscopic Therapy for Chronic Pancreatitis
ERCP for Biliary Strictures Associated with Chronic Pancreatitis
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