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Biliary Stents Pose Relative Risks, Benefits to Patients
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Q: What Is the Role of Metal Biliary Stents in Patients With Unresectable Pancreatic Cancer and Jaundice?
A: More than 33,000 people are diagnosed with pancreatic cancer in the United States every year. Only 15% to 20% of the patients who are diagnosed with pancreatic cancer will have resectable disease at the time of initial presentation. The median survival of these patients varies from 3 to 6 months (for patients with remote metastases) to 7 to 12 months (those with locally advanced, unresectable pancreatic cancer). Patients with the cancer located in the pancreatic head usually present with obstructive jaundice and pruritis, and palliation of these symptoms and its consequences significantly improve patients’ quality of life.
Endoscopic retrograde cholangiopancreatography (ERCP) has become the main therapeutic tool in palliation of biliary obstruction in patients with pancreatic cancer. If, prior to the ERCP, I am not sure whether the patient will be a candidate for surgical resection, I will place a plastic biliary stent of the largest available diameter (usually 10 Fr). If this patient will subsequently undergo surgical resection of the pancreatic cancer, the plastic stent can be easily removed prior to or, more commonly, during surgery.
In pancreatic cancer patients who are not surgical candidates (patients refusing or unable to tolerate surgery due to their general condition and those with locally advanced or metastatic disease), obstructive jaundice could be palliated with placement of either plastic or metal stents. Plastic stents are less expensive, but they are smaller in diameter (only 7 to 11.5 Fr) compared to metal stents, which expand to 10 mm (30 Fr) after placement. Due to a relatively small diameter, plastic stents rarely function longer than 2 to 3 months, and all will ultimately clog. If the patient’s general condition is poor and his or her life expectancy is less than 3 months, I usually place a plastic stent, as the stent is likely to function until the patient’s demise. However, my initial assessment of the patient’s life expectancy could be wrong, and if this patient lives longer and then presents with an occluded plastic stent, it can always be exchanged for another plastic stent or changed to a metal stent.
Figure 1. Proper position of the biliary metal stent through the major duodenal papilla in June 2009.
Figure 2. Tumor ingrowth caused complete occlusion of the biliary metal stent in April 2010.
Figure 3. Extraction balloon pulled through the metal stent removing biliary sludge, stones, and debris.
Figure 4. Metal stent patency restored.
Images: Kantsevoy SV
There are 2 major designs of self-expanding metal stents: uncovered (made of bare wire mesh) and covered (wire covered with a plastic coating). Stents may be partially covered or fully covered. The coating reduces tumor ingrowth through the stent and may increase the long-term patency of these devices compared to uncovered stents. However, in patients with an intact gallbladder, a placement of a covered stent above the confluence between the cystic duct and common bile duct may block the cystic duct and can cause cholecystitis. To avoid such a complication, the proximal end of a covered biliary metal stent should be placed below the confluence with the cystic duct. If the patient’s anatomy will not allow metal stent placement without blocking the entrance to the cystic duct, then an uncovered metal stent may be the best choice.
The length of the stent should be chosen to completely bypass the entire length of the occluded common bile duct and allow at least 5 to 10 mm of the stent above and below the occlusion.
Deployment of the metal stent should be done under fluoroscopic and endoscopic observation. Fluoroscopic guidance allows precise control of the placement of the proximal end of the stent. At the same time, endoscopic observation allows us to control the position of the distal (intraduodenal) end of the stent in patients undergoing transpapillary stent placement. Appropriate position of both ends of the stent is equally important: if the proximal (biliary) end of the stent is too close to the site of the obstruction, it will be rapidly blocked by the tumor overgrowth. If the distal (duodenal) end of the stent is too short, it will be quickly blocked by the tumor ingrowth. If the distal end of the stent is too long, the stent can rub against the contralateral duodenal wall and cause erosions, ulcers, bleeding, and even perforation.
Figure 5. Second metal stent placed inside the originally placed biliary stent.
Properly placed metal biliary stents (Figure 1) usually last for at least 8 to 12 months. However, the metal stents can be blocked by tumor ingrowth, sludge, and biliary stones (Figure 2). Patients with occluded biliary stents usually complain of skin itching, followed by dark discoloration of the urine and jaundice of the skin and sclera. The restoration of the biliary stent patency in patients with unresectable pancreatic cancer should be done as quickly as possible due to the risk of ascending cholangitis. Injection of contrast through the stent during ERCP confirms the level and extent of occlusion. Tumor, biliary sludge, stones, and debris can be removed by pulling the inflated balloon down through the occluded stent (Figures 3 and 4). Bleeding may occur but is usually self-limited. If stent occlusion is caused by tumor ingrowth through the wire mesh of the stent, the placement of a second metal stent inside the original stent can restore the luminal patency (Figure 5).
Overall, the decision of whether to place a metal or plastic stent should be individualized, and patients should be made aware of the relative risks and benefits of the options available.
Excerpted from:
Kantsevoy SV. Curbside Consultation in GI Cancer for the Gastroenterologist (pp 93-97). ©2015 SLACK Incorporated.
References:
Jemal A, Siegel R, Ward E, et al. Cancer statistics, 2006. CA Cancer J Clin. 2006;56(2):106-130.Davids PH, Groen AK, Rauws EA, Tytgat GN, Huibregtse K. Randomised trial of self-expanding metal stents versus polyethylene stents for distal malignant biliary obstruction. Lancet. 1992;340(8834-8835):1488-1492.
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