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Esophageal stents
A recent American College of Gastroenterology study reviewed the available evidence regarding the various uses of esophageal stents and provided an assessment of the quality of the evidence and the strength of the recommendations for a range of indications. The researchers found that the most common indications for the use of esophageal stents were malignant obstruction, extrinsic compression, refractory strictures, and esophageal perforations and leaks. The incidence of these indications has increased significantly during the last two decades, as has as the number of patients undergoing stent placement, as stent technology has evolved and the safety and ease of stent placement have improved. In this chapter, we will briefly review the evolution of stent technology, including the current standard of care, the technique for stent placement, and the various indications for placement of an esophageal stent.
STENT TECHNOLOGY
Esophageal stent technology has evolved significantly during the past two decades, replacing rigid prosthetic stents such as the Celestin tube and Atkinson’s tube—which were difficult to deploy and were associated with high complication (perforation, migration, occlusion, airway compression) and mortality rates—with self-expandable metallic stents (SEMS). The advantage of SEMS over rigid stents was initially confirmed in a prospective trial published in 1993, and SEMS have since become the standard of care. SEMS are primarily composed of a metallic mesh of nickel-titanium metal alloy (nitinol), which allows the stent to retain its shape and to conform to a variety of shapes while maintaining adequate radial pressures. Initially, stents were fully uncovered (fully exposed metallic mesh component), but because of the occurrence of tumor and granulation tissue ingrowth between the wire mesh, partially covered stents that primarily used polytetrafluoroethylene as the covering material were developed. An advantage of partially covered stents is that the covered component minimizes ingrowth while leaving the metal ends exposed, which allows the stent to attach to the underlying mucosa and lessens the risk of stent migration. Currently, the various brands of partially covered SEMS differ with regard to design, including the presence or absence of braiding (braiding shortens the length of the stent during deployment by 30% on each end), length, diameter, radial strength, and deployment mechanism. However, numerous studies have found there is no meaningful advantage of any of the currently available brands of partially covered SEMS.
INDICATIONS FOR STENT INSERTION
Esophageal stents in unresectable disease
An increasing incidence of esophageal cancer in the Western hemisphere is occurring without a concomitant increase in the rate of early detection. Consequently, the number of patients presenting with advanced stage disease (not appropriate for surgery or irradiation) is increasing at an alarming rate, and the need to provide these patients with obstruction (a). A self-expandable metallic stent (SEMS) has been inserted to open up the lumen of the esophagus before initiation of chemoradiotherapy (b). palliative treatment options to maintain their quality of life is increasingly relevant. Among the most debilitating symptoms in patients with advanced stage esophageal cancer is dysphagia. Advancements in stent technology during the past two decades have dramatically improved the management of this condition, by far the most common indication for the placement of an esophageal stent. Unlike for other indications, the goal of treatment of malignant strictures and obstruction from tumor encroachment is to durably improve dysphagia while minimizing the risks of the intervention and the need for reinterventions. Overall, when SEMS are used to palliate malignant esophageal obstruction, they are cost-effective, efficient, and successful at palliating patients (see Figure 28.1 ).
28.1 Esophageal lumen obscured by a malignant
Esophageal stents for trachea-esophageal fistula
Malignant trachea-esophageal fistula (TEF) occurs in 5%–15% of patients with esophageal cancer. TEFs can occur as a direct consequence of tumor invasion, or they can be iatrogenic in patients who have received chemoradiation, which were probably invading the airway wall. A bronchoscopic examination should be performed to exclude airway invasion before contemplating radiation treatment in any patient with a bulky proximal or mid-esophageal tumor. Once a fistula occurs, the life expectancy of the patient is 1–3 months. The most common site of invasion and fistula formation is the trachea, followed by the left mainstem bronchus. Given the typically poor prognosis and physical condition of patients with TEFs, surgical management is rarely indicated (diversion or bypass), and so a durable yet minimally invasive treatment is the most appropriate. Most often, these patients are managed with partially covered SEMS with a high success rate; alternatively, airway stents are a possible choice. Occasionally, parallel airway and esophageal stents are required to occlude the fistula in these patients (Figure 28.2 a and b).
28.2 An iatrogenic post-chemoradiation fistula between the proximal esophagus and the trachea (a). A fully covered selfexpandable esophageal stent (SEMS) has been inserted to occlude the fistula (b).
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