Pancreatic cancer often requires the use of a stent, a small, hollow tube placed inside a body passage to keep it open. This procedure is typically required when the tumor causes an obstruction, either for palliative care or as preparation for surgery and subsequent treatment. Stenting provides an immediate solution to severe symptoms, improving a patient’s overall condition before they undergo chemotherapy or radiation. The decision to place a stent is based on the cancer’s stage and the patient’s immediate clinical needs, prioritizing symptom relief and stabilization for the continuation of therapy.
The Role of Stents in Managing Obstruction
The primary indication for stenting in pancreatic cancer is the management of malignant obstruction, most commonly affecting the bile duct. The tumor’s growth can compress the common bile duct, which runs through the head of the pancreas. This compression prevents bile from draining into the small intestine, causing biliary obstruction.
Stent placement immediately treats the resulting jaundice, characterized by yellowing of the skin and eyes. Biliary obstruction can also lead to life-threatening infections such as cholangitis, an infection of the bile duct system. By restoring the flow of bile, the stent relieves jaundice and reduces the risk of severe infection, serving a palliative role.
In cases where the patient is scheduled for neoadjuvant therapy (treatment given before surgery), bile drainage is essential. Elevated bilirubin levels caused by jaundice can interfere with the liver’s ability to process chemotherapy drugs, potentially delaying necessary treatment. A biliary stent helps normalize liver function, stabilizing the patient so they can safely proceed with chemotherapy and radiation.
Pancreatic cancer can also cause duodenal obstruction by pressing on the duodenum, the first part of the small intestine. This blockage, also known as gastric outlet obstruction, prevents food from passing out of the stomach. This leads to persistent nausea, vomiting, and an inability to eat. Placing a duodenal stent restores the passage for food, allowing the patient to maintain nutrition and hydration.
Different Types of Stent Materials and Designs
The choice of stent material depends on the patient’s expected duration of life and the overall treatment plan. Biliary stents are classified into two main types: plastic stents and self-expanding metal stents (SEMS). Plastic stents are made of polyethylene or Teflon and are considered a temporary solution because they have a smaller diameter and are prone to clogging.
Plastic stents are favored for patients with a short life expectancy (less than three months) or for temporary drainage before a planned surgical resection. These stents usually remain patent for about three to six months before requiring replacement. Their temporary nature is due to the buildup of bile sludge and bacteria, which eventually blocks the small lumen.
Self-expanding metal stents (SEMS) are the preferred choice for palliative care in patients with an expected survival of greater than six months. These stents are inserted in a compressed state and expand once deployed, offering a wider diameter that reduces the risk of blockage. SEMS can remain open for a longer period, often eight to twelve months or more, minimizing the need for repeat procedures.
For duodenal obstruction, a specific type of SEMS is used to bypass the blockage in the small intestine. These duodenal metal stents are designed to be flexible and durable to withstand movement and pressure within the digestive tract. The stent provides long-lasting relief from vomiting, enabling the patient to resume oral intake and supporting their strength during cancer treatment.
How Stents Are Placed Endoscopically
Stent placement is a minimally invasive procedure performed using specialized endoscopic techniques, often requiring only a short hospital stay or being done on an outpatient basis. The most common method for accessing the bile duct is Endoscopic Retrograde Cholangiopancreatography (ERCP). During ERCP, a flexible tube with a camera is passed through the mouth, stomach, and into the duodenum to reach the opening of the bile duct.
The endoscopist guides a wire through the blockage and then deploys the stent over this wire to hold the duct open. ERCP is the standard first-line approach for resolving biliary obstruction. The procedure is performed under sedation and allows for immediate confirmation that the stent is correctly positioned and the bile flow is restored.
When ERCP is not feasible due to a tumor-induced blockage in the duodenum or complex anatomy, an alternative technique called Endoscopic Ultrasound (EUS)-guided drainage is employed. EUS uses an endoscope with a small ultrasound probe at the tip to create detailed images of the pancreas and surrounding structures. The EUS allows the endoscopist to precisely puncture the bile duct or duodenum and deploy the stent through this newly created pathway.
EUS-guided drainage is used for patients with an existing duodenal stent or those with a history of complex gastrointestinal surgery. While technically more challenging, EUS-guided procedures offer a comparable success rate to ERCP. Both methods provide a less invasive alternative to surgical bypass for relieving the obstruction.
Monitoring and Potential Issues After Placement
Following stent placement, patients require careful monitoring, as the devices are subject to complications over time. The most frequent issue is stent blockage, or occlusion, which occurs when bile sludge, food debris, or tumor growth obstructs the stent’s lumen. Blockage is more common with plastic stents due to their narrower diameter, often leading to a recurrence of jaundice and fever, which signals cholangitis.
Another concern is stent migration, where the device moves out of its intended position. Migration can lead to the return of obstructive symptoms or cause irritation and pain in the surrounding tissues. If a stent becomes fully blocked or moves, a repeat endoscopic procedure is necessary to clean the clogged stent or replace it.
Patients receiving a plastic stent for temporary drainage must be scheduled for a replacement procedure every few months to prevent occlusion. Metal stents offer a longer patency time, but they can still eventually become blocked by tumor ingrowth or overgrowth. Post-procedure pain and pancreatitis are potential short-term complications, managed with medication and close observation.