Malignant bile duct obstruction is most commonly seen in pancreatic cancer, but also in cholangiocarcinoma, gallbladder cancer and jugular abdominal tumors.
I. Clinical features.
Most patients with malignant tumors of the pancreaticobiliary system usually have symptoms of painless jaundice, loss of appetite and weight loss. If pain is present, it usually appears in the middle and upper abdomen or right upper abdomen and may be accompanied by radiating pain in the back. Back pain usually indicates retroperitoneal infiltration of the tumor and also predicts that the tumor may be unresectable. Other symptoms may include black stools, clay-like stools, and itching. Abnormal glucose tolerance or overt diabetes mellitus may be present in 80% of pancreatic cancers. Tumors in the body or tail of the pancreas can present similarly to those described above. A thorough physical examination is essential. Chest radiology can evaluate for pulmonary metastases. Serologic testing for tumor markers is also necessary. Abdominal imaging should be performed once the patient can occasionally rate the possibility of pancreaticobiliary malignancy based on clinical manifestations. Xu Hongwei, Department of Gastroenterology, Shandong Provincial Hospital
Diagnosis: Diagnosis is made according to clinical manifestations, laboratory tests and imaging examinations.
III. Treatment.
If the diagnosis of malignant tumor of pancreaticobiliary duct is suspected by combination of clinical and ultrasound examination, further imaging examination is needed to clarify the diagnosis and determine the stage of tumor, so as to clarify the possibility of surgical resection or choose appropriate and effective palliative treatment. It is especially important to identify the location of the obstruction, because the differential diagnosis and treatment options vary from location to location. Theoretically, different treatments should be used for inferior or proximal biliary obstruction. Patients with inferior bile duct obstruction should be treated endoscopically or surgically drained, whereas patients with proximal obstruction should be treated with intrahepatic anastomosis or percutaneous drainage. The choice of the best treatment option for patients with malignant biliary obstruction should take into account the characteristics of the different imaging studies, the cause and location of the obstruction, the risk of cholangitis due to cholangiosystemic imaging and the possibility of radical or palliative treatment. Recent data suggest that non-invasive cholangiography can largely assist endoscopic drainage and reduce septic complications following failed attempts at unilateral or bilateral drainage.
(i) Radical surgery
For patients with lower biliopancreatic duct tumors with indications for surgery, radical surgery should be performed for resection in the absence of clear signs of metastasis and local vascular infiltration. Unfortunately, these patients only account for 10-20% of all cases. Many elderly patients are not suitable for surgical treatment due to advanced age or coexisting other diseases. Surgical treatment should be recommended for patients with promise of surgical resection.
(ii) Palliative treatment
There are three important conditions that need to be treated in patients with inoperable cholangiocarcinoma or pancreatic cancer: biliary stasis, pain, and gastrointestinal obstruction. This is caused by local infiltration of adjacent tissues or organs by the tumor.
1. Endoscopic stenting.
(1) Background: Soehendra et al. first proposed an alternative treatment option to biliary shunts for patients with high-risk or surgically unresectable tumors, namely endoscopic biliary plastic stent placement. Self-expanding metal stents for the biliary system were not clinically available until 10 years thereafter. The diameter of the plastic stent is limited by the size of the endoscopic biopsy orifice. The self-expanding biliary metal stent is free from this limitation and can reach 10 mm in diameter, but its price is higher than that of the plastic stent.
(2) Indications: Cholangitis or pruritus in patients with moderately advanced malignant bile duct obstruction is an indication for bile duct decompression. Bile duct stent placement can also relieve the symptoms of loss of appetite, thus improving the quality of life. Patients with intermediate to advanced malignancy are not routine indications for biliary system drainage because the risk of complications arising from the operation outweighs the potential therapeutic benefit. In fact, only supportive therapy alone is required for asymptomatic patients with obstructive jaundice and liver metastases. Preoperative jaundice is considered to be a symptom of the poor state of the organism, and if it can be relieved before pancreaticoduodenectomy, the outcome of the operation can be improved. However, routine preoperative drainage of the obstructed biliary system has not shown any benefit for patients undergoing immediate surgery and, in fact, has been shown to be harmful in some cases. If surgery is delayed due to cholangitis or clinically significant symptoms, drainage is routinely performed with plastic stents. Recent cost-saving studies suggest that a short, self-expanding metal stent is best used preoperatively.
(3) Plastic stents.
Plastic stents are simple to implant and can be removed when necessary. The greatest advantage of plastic stents over metal stents is their extremely low price. Most of the plastic stents have an inner diameter of 5-11.5 Fr and a length of 5-15 cm. straight stents with side holes and tails at both ends are the most common types. The tail at both ends minimizes the risk of stent movement, as in the case of pigtail stents, which have physical properties that allow them to be firmly anchored in the common bile duct and duodenum. Although there are no clear studies on the occlusion and migration rates of straight and pigtail biliary stents, animal studies have shown that straight stents provide better bile drainage than pigtail stents. The main drawback of plastic stents is the short patency time and the possibility of occlusion.
Many studies have investigated the causes of plastic stent occlusion. Although most recent studies have focused on the importance of fiber ingestion, most previous studies have emphasized bacterial colonization of the stent lining resulting in bacterial biofilm formation and subsequent stent occlusion. The above findings have led to adjustments in stent design or the use of adjunctive agents to achieve a longer time frame for stent patency.
(4) Self-expanding metal stents.
The idea of placing expandable metal stents (SEMS) in the biliary system originated from stents used in vascular stenosis. sEMS are made of surgical grade alloys woven into the shape of a tubular screen. The elasticity of the metal stent allows the stent to change shape depending on the position and force applied, and the SEMS can enter the bile duct by being compressed by the sheath into a small circumferential placement system. When the outer sheath of the stent is slowly withdrawn from the lower end of the stent, the stent is restored to its original shape by the force of metal expansion. The laminated metal stent has a physical barrier to inward tumor growth and is thought to hold promise for prolonged patency.
(5) Stent selection in palliative care.
The choice of the most appropriate stent for palliative treatment of malignant bile duct obstruction depends on a variety of factors and varies from patient to patient. The primary choice is the decision of stent type (plastic or metal stent), which depends on a variety of stent-related factors such as stent efficacy (relief of jaundice), duration of patency, need for re-intervention, and cost. In addition, patient-related factors such as disease extent and desired survival time need to be considered and influence the choice of an ideal, cost-effective stent.
Many studies have been performed to compare the use of plastic stents or SEMS in the palliative treatment of malignant bile duct obstruction. 95% of patients see relief of jaundice and improvement in liver function after placement of either plastic or metal stents, so there is no significant difference between the two from this perspective. However, the median time to patency was 2-5 months for plastic stents and 4-10 months for SEMS. The shorter duration of patency with plastic stents requires additional endoscopic interventions. The median survival of patients was 4-6 months after placement of either biliary plastic stents ah or metal stents. Studies have shown that the use of SEMS is beneficial for prolonging survival in patients with malignant obstruction of the lower bile duct compared to plastic stents, and that SEMS may provide a longer survival time in the palliative treatment of malignant bile duct obstruction. Cost-effectiveness analysis showed that the choice of stent was influenced by the cost ratio of stent to ERCP and the expected survival of the patient. The higher the cost of ERCP, the more likely it is that a metal stent should be used. However, estimating survival for malignant bile duct obstruction is difficult. For patients with tumors larger than 3 cm or liver metastases, there is a tendency to consider plastic stents because they are more cost effective for patients with survival of about 3-4 months. Metal stents, on the other hand, are mostly used for patients with an expected survival of >6 months.
Although these factors need to be taken into account when selecting a stent, there are no clear criteria for choosing plastic or metal stents in palliative care for patients with malignant bile duct obstruction that cannot be surgically removed. In fact, the choice of stent should be individualized because it is impossible to ignore the patient’s own factors.
(6) Optimal stent placement strategy
In addition to considering the most appropriate stent (plastic stent versus SEMS), the endoscopist should also consider the best stent placement strategy. For example, if a plastic stent is initially placed, should the stent be changed at regular intervals to prevent occlusion, or should it be changed on an as-needed basis? A randomized study showed that patients who regularly changed stents every 3 months had a longer symptom-free period than those who changed stents only after developing symptoms of obstruction, but there was no significant difference in overall survival between the two.
Blocked metal stents can be treated in a variety of ways. The most common options include placing a plastic stent inside the obstructed metal stent, placing a second metal stent, and mechanically clearing the lumen of the obstructed stent. Reconstruction of biliary drainage can have a success rate of more than 80%. Mechanical clearance methods, such as flushing with a catheter or applying a lithotripsy airbag, have a lower success rate and shorter time to patency than stent replacement. Since the median survival period after initial biliary metal stent obstruction is relatively short, a single plastic stent recanalization approach is the most cost-efficient.
2.Percutaneous stenting
Percutaneous stenting is a method of placing plastic or metal stents in patients with malignant obstruction of the lower bile duct after failed endoscopic placement. Only in recent years has percutaneous biliary drainage become the preferred palliative treatment for patients with malignant obstructive jaundice. Percutaneous biliary drainage is as effective and has inherent advantages as endoscopic bypass drainage. However, the disadvantages of percutaneous biliary drainage are spontaneous displacement of the percutaneous catheter, inflammation and pain at the puncture site, extravasation of ascites and bile around the catheter, and loss of water and electrolytes. The complication rate of transhepatic bile drainage does exist and varies depending on the status of the patient prior to the operation and the diagnosis. Coagulation disorders, cholangitis, gallstones, malignant obstructive or intrahepatic lesions are associated with a higher complication rate.
3.Surgical palliative treatment
In the past, surgical palliative treatment was the preferred method, but now it has been replaced by percutaneous or endoscopic stenting. Surgical palliative treatment of pancreatic cancer and bile duct cancer has a high 30-day mortality rate, especially in the elderly or in patients with metastases. Patients with chronic abdominal pain are suitable for surgical bile-intestinal bypass because the abdominal nerves can be blocked intraoperatively. The need for prophylactic bile-intestinal shunts in patients with malignant obstructive jaundice and the timing of surgery are inconclusive.
(iii) Adjuvant therapy
Although patients with lymphoma presenting with biliary obstruction may be treated with biliary stenting or surgical shunts, cure is only possible with remission of the primary disease. Responsiveness to chemotherapy remains the main indicator of prognosis in these patients. Conversely, the preferred treatment for tumors of epithelial origin is surgical resection, although adjuvant chemotherapy may improve 1- and 5-year survival rates after resection of pancreatic cancer. For patients who cannot undergo surgical resection, the role of chemotherapy remains very limited.
VI. Summary
Malignant obstruction of the lower biliary tract is a frequently encountered disease among endoscopists and requires multidisciplinary cooperation between surgeons, radiologists and gastroenterologists. The best solution to this complex medical dilemma depends more on expert technique than on the basis of the literature. Endoscopic techniques have evolved rapidly over the past 20 years and now play a central role in the palliative treatment of malignant diseases of the distal biliopancreatic duct. (From ERCP Xue-Gang Guo and Kai-Chun Wu)