Biliary tract drainage, with or without placement of an endoprosthesis, is used as a palliative therapy for malignant biliary obstruction. The first truly internal endoprostheses represented a distinct improvement over internal-external catheters but still remained patent for only 4 to 6 months. Metallic stents have a long-term patency of 6 to 8 months. At present, it appears that patients with unresectable pancreatic cancer should be palliated with endoscopically placed plastic or metal stents, whereas those with malignant obstructions higher in the biliary tree are probably better managed with transhepatically placed stents. The combination of brachytherapy plus external-beam radiation followed by implantation of a Gianturco metal stent may be a viable approach to treating obstructions in patients with cholangiocarcinoma. For those with other noncholangiocarcinomas, particularly when life expectancy exceeds anticipated stent patency duration, the Wallstent may be the device of choice. [ONCOLOGY 9(6):493-504, 1995]
Biliary tract drainage, with or without placement of an endoprosthesis, is used as a palliative therapy for malignant biliary obstruction. The first truly internal endoprostheses represented a distinct improvement over internal-external catheters but still remained patent for only 4 to 6 months. Metallic stents have a long-term patency of 6 to 8 months. At present, it appears that patients with unresectable pancreatic cancer should be palliated with endoscopically placed plastic or metal stents, whereas those with malignant obstructions higher in the biliary tree are probably better managed with transhepatically placed stents. The combination of brachytherapy plus external-beam radiation followed by implantation of a Gianturco metal stent may be a viable approach to treating obstructions in patients with cholangiocarcinoma. For those with other noncholangiocarcinomas, particularly when life expectancy exceeds anticipated stent patency duration, the Wallstent may be the device of choice.
Whereas surgery is still the gold standard for eradicating biliary and other intestinal tumors, percutaneous transhepatic biliary drainage, with or without placement of an endoprosthesis, has become an integral part of the treatment of biliary obstruction over the past 15 years[1,2]. Biliary drainage is a well-accepted means of palliation for malignant biliary obstruction that has been used both preoperatively and as the primary treatment in patients whose disease is deemed unresectable .
Role in Treating Different Tumors
Biliary obstruction is caused by a wide range of tumors, and therefore, therapy of the obstruction differs markedly, depending on the lesion involved. Ampullary carcinoma is preferably treated surgically with a Whipple procedure, and endoscopic biliary drainage is employed only in exceptionally high-risk patients or those with metastatic disease. In contrast, carcinoma of the pancreas is frequently treated by biliary drainage, as the majority of patients with this cancer present with advanced disease. In this situation, the drainage is often performed endoscopically, since the primary stricture is usually low-lying within the common bile duct.
High obstruction at the ductal confluence, which is beyond the reach of most endoscopists, may be caused by cholangiocarcinoma, gallbladder carcinoma, or adenopathy in the porta hepatis secondary to a variety of metastases. Biliary drainage is often the primary therapy for gallbladder carcinoma and adenopathy in the porta hepatis, since, by the time gallbladder carcinoma causes biliary obstruction, it is usually inoperative. Cholangiocarcinoma, when resectable, may be treated operatively with a hepaticojejunostomy. However, the majority of patients with a Klatzkin-type stricture at the bile duct confluence have more extensive intrahepatic disease at presentation that precludes curative surgical resection and/or pose too great a surgical risk.
Postoperative patients may also develop jaundice secondary to biliary obstruction. The concern in such patients is usually recurrent malignancy; however, a stricture may simply represent a late-presenting anastomotic stenosis. Benign anastomotic stenoses are well-treated by biliary drainage combined with balloon dilatation, whereas palliative drainage is the treatment of choice for recurrent disease .
Jaundice alone is not an indication for percutaneous transhepatic biliary drainage. The general indications for biliary tract drainage are jaundice associated with cholangitis, sepsis, pruritus, and nausea and vomiting leading to dehydration and malnutrition. In patients with these symptoms, biliary drainage offers significant palliation, and the benefits of the procedure outweigh the major risks, which include bleeding, bacteremia and/or sepsis, hepatic injury, and pneumothorax. Initial transhepatic cholangiography is necessary to define the extent of an obstruction, particularly with cholangiocarcinoma, and to plan for surgery.
Preoperative biliary drainage in patients who are jaundiced but otherwise asymptomatic, especially those with carcinoma of the pancreas, has not been found to be beneficial, but should be employed in the rare patient presenting with acute ascending cholangitis. Occasionally, the presence of a catheter in the extrahepatic bile duct may assist the surgeon in creating a biliary bypass, in which case preoperative endoscopic or transhepatic drainage may be considered.
Biliary drainage was first described in 1974 by Molnar and Stockum  and was popularized in 1978 by Ring, who developed a suitable catheter for internal drainage . Initially, external drainage was the treatment of choice, but it has the inconvenience of a catheter with bile draining into a bag. Prolonged external drainage of bile has the added disadvantage of electrolyte loss leading to metabolic imbalance. Occasionally, however, it may be necessary, particularly in patients who have high intra-abdominal or intraluminal pressures within the duodenum and who have persistent leaks alongside their catheter. Various techniques have been developed to readminister this "lost" bile enterically, but these are often quite difficult to tolerate.
Internal-External Catheters--As a result of these problems, internal drainage with an internal-external catheter became the standard therapy for nearly 10 years. These transhepatic catheters are designed with side holes both above and below the level of obstruction in the biliary tree; the tip of the catheter resides within the bowel, so that bile drains through the catheter across the obstruction and out of the side holes into the duodenum. Although biliary obstructions are usually complete, it is almost always possible for a trained interventional radiologist to negotiate through a stricture with a combination of guidewires and catheters under fluoroscopic guidance. With placement of an internally draining catheter, nutrition is improved, and metabolic imbalance no longer becomes an issue.
Most transhepatic biliary catheters are routinely changed every 2 months to avoid any chance of obstruction.
If such problems as deep pain, fever (> 101° F), or leakage around the catheter onto the dressing develop, they can be managed simply by exchanging the catheter for a new one. However, external-internal catheters are a potential source of bacterial infection, are prone to dislodgment and obstruction, and may be uncomfortable.
Furthermore, for many patients the external catheter is a constant reminder of their cancer. Less frequently, it may be regarded as a "lifeline," the device that saved the patient from death. Therefore, maintenance of the catheter becomes the main focus of the patient's life, and any problems that develop may be perceived as a threat to his or her existence. Both of these psychologically disruptive feelings encouraged the search for a truly internal device.
Early Internal Devices--The first devices to achieve this goal were a variety of endoprostheses, particularly the Carey-Coons stent (12 French [4 mm] in diameter), which is used for distal common bile duct strictures, such as that seen with carcinoma of the pancreas; and the Miller stent, a double mushroom design used for more proximal disease, as can be seen with cholangiocarcinoma. These devices were designed to be implanted following an initial trial of internal-external drainage. If internal drainage was achieved satisfactorily by capping an internal-external catheter (thereby forcing bile to flow into the duodenum), the internal-external catheter could then be exchanged for an endoprosthesis that was positioned over a guidewire, after which the percutaneous access site was allowed to heal over.
Because nothing protrudes externally from the patient's side, internal stents are generally tolerated much better by patients. However, the expected patency of these synthetic catheters is only on the order of 4 to 6 months. Radiologists originally used Teflon for these catheters, but this material was found to have a high rate of encrustation with sludge and bacteria, which are the predominant sources of catheter obstruction.
Metallic Stents--In the late 1980s metallic stents came into use (see Figure 1). These self-expanding stents may be introduced through a sheath the same size as the initial biliary drainage catheter. When deployed, they expand up to 10 mm (30 French) in diameter .
In essence, the theoretical advantage of metallic stents is that they provide a significantly larger lumen within the bile duct without creating a large access hole within the liver. It was believed that a much larger lumen would allow for a considerable increase in patency. Furthermore, metal is not reactive in the biliary tree, and progressively becomes incorporated into the wall of the bile duct over several weeks' time.
In reality, however, patency remains a problem with stented malignant biliary tract obstructions. Tumor ingrowth through the struts of the stent and overgrowth over the ends of the stent have proved to be major limitations of these newer devices.  The wider struts of the zigzag Gianturco Z stent appear particularly susceptible to tumor ingrowth. The woven mesh of the Wallstent design was first reported by European researchers to be better, but it, too, is susceptible to both tumor overgrowth and occasional ingrowth .
To avoid tumor overgrowth and ingrowth, stenting over an extended length of duct has been recommended. However, it does not totally solve these problems. Silicone coating of the stents has been proposed and tried in Europe, but no long-term data are available. Inspissated bile may obstruct these stents, despite their relatively large diameters.
Recent work suggests that the long-term patency of metal stents alone in the treatment of malignant obstruction is little more than 6 to 8 months [6-8]. However, in patients with carcinoma of the pancreas or gallbladder, whose survival is generally limited, this approach may provide sufficient palliation. Endoscopic stent placement has become the primary approach for most patients with carcinoma of the pancreas, since the obstruction tends to be low-lying in the bile duct. Also, this approach avoids the potential problems of hemobilia and pneumothorax associated with transhepatic drainage. As a technique, endoscopic retrograde stent placement may be less painful for the patient [2,3].
Patients with cholangiocarcinoma may represent a different subcategory. Work in the mid-1980s demonstrated that cholangiocarcinoma is very responsive to local radiation therapy. Intracavitary therapy, or brachytherapy, which involves administering the radiation through an internal-external catheter, provides a high dose of radiation directly to the tumor while avoiding excessive radiation damage to the surrounding viscera [9-12].
The impact of radiation dose on both survival and morbidity in combined- modality treatment of 48 patients with cholangiocarcinoma treated at Thomas Jefferson University Hospital was recently reviewed . From 1984-1990, 24 patients received external-beam radiation, a brachytherapy implant through internal-external catheters, and chemo- therapy as part of a combined-modality approach, whereas 24 patients received no radiation as part of their treatment. Patients treated with radiation had a 30% 2-year survival rate (median, 12 months) vs 17% (median, 5.5 months) for patients not treated with radiation. Furthermore, patients receiving a total dose greater than 55 Gy had an extended 2-year survival rate of 48% (median, 24 months) vs a 0% extended 2-year survival (median, 6 months) in those given total doses less than 55 Gy. Surgical resection and/or chemotherapy without radiation did not produce any statisti-
cally significant benefit as independent variables .
Stents Plus Brachytherapy
We are currently reviewing our long-term experience with metallic stents combined with intraluminal iridium 192 (brachytherapy) plus external-beam radiation for the treatment of malignant biliary obstruction. Following transhepatic biliary drainage (see Figures 2A, 2B and 2C), our procedure is to pass a wire implanted with iridium seeds through the internal-external catheter for local radiation. Once brachytherapy is completed, metallic stents are placed so as to extend beyond the level of the tumor stricture, and all external catheters are subsequently removed. External-beam therapy is then continued on an outpatient basis.
From 1989 to the present, we have treated 22 patients with inoperable malignant biliary obstruction due to cholangiocarcinoma, pancreatic carcinoma, gallbladder carcinoma, or metastatic disease with percutaneous transhepatic biliary drainage followed by intraluminal iridium-192 wire placement, implantation of Gianturco self-expanding metallic stents, and external beam radiation therapy. For 11 patients with cholangiocarcinoma, a mean dose of 25.55 Gy (range, 14.5 to 31 Gy) was delivered via intraluminal iridium at a 1-cm radius while 11 patients with noncholangiocarcinoma malignancies received a mean dose of 24.94 Gy (range, 14.82 to 30 Gy). Additional external-beam radiation was delivered to 8 of the 11 patients with cholangiocarcinoma (mean dose, 45.18 Gy) and to 3 of the 11 patients with noncholangiocarcinoma malignancies (mean dose, 51.33 Gy). The majority of the patients who had nonchol- angiocarcinoma malignancies had received prior external-beam therapy in maximum doses and were therefore not candidates for additional treatment.
Over a mean follow-up period of more than 1 year, intraluminal iridium- 192 and external-beam therapy appears to extend metallic stent patency in the biliary tree in patients with inoperable cholangiocarcinoma. In contrast, this approach seems to offer no advantage in other malignancies involving the biliary system. The results with cholangiocarcinoma are encouraging, since stent obstruction due to tumor ingrowth and/or overgrowth may be relieved.
At present, it appears that patients with inoperable carcinoma of the pancreas should continue to be palliated with plastic or metal stents placed endoscopically. Other malignant obstructions higher in the biliary tree are probably better managed with stents placed transhepatically by an interventional radiologist. If the patient's life expectancy is short, cost considerations generally favor plastic stents.
If the obstruction is due to cholangiocarcinoma, the combination of brachytherapy and external-beam radiation therapy followed by Gianturco metal stent placement appears to be a very viable alternative. With other noncholangiocarcinoma malignancies, especially if the patient's life expectancy may exceed the duration of stent patency, the Wallstent may be the stent of choice. Hopefully, silicone-covered stents will prove to be superior in this population.
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