Stent therapy

DEFINITION: Stent therapy involves placing a rigid plastic or expandable metal tube to open a blocked airway, a stenosed blood vessel, the colon, or the esophagus.

Cancers treated:Lung cancer, esophageal cancer, colon cancer, gastric carcinoma, vena cava syndrome

Why performed: When cancerous growth constricts or occludes an airway or major blood vessel, a stent can be an important option if tissue removal alone is not effective. Stents can strengthen a weakened airway or blood vessel.

Stents are used as an entro-endo for colonic stenting and gastroduodenal stenting. Such stents are used for preoperative relief of obstruction and for palliative treatment. Stricture formation can be a major problem among patients who have an between the esophagus and stomach or jejunum following subtotal or total gastrectomy.

Although first used as a simple adjunct to radiotherapy, stenting of the superior vena cava can be an effective first-line procedure for immediate relief in patients with malignancy. The growth of malignant lesions surrounding the vena cava often causes stenosis or obstruction, resulting in symptoms of venous congestion, the so-called vena cava syndrome. Stent therapy can be effective in treating such cases and improving the quality of life for patients with advanced malignant disease.

Patient preparation: Patients diagnosed with superior vena cava (SVC) syndrome caused by severe stenosis secondary to mediastinal malignancy may be referred for stent insertion. Most cases of SVC syndrome are attributable to an underlying primary thoracic malignancy, lymphoma, or metastatic tumor. Symptoms include venous congestion and edema in the upper half of the body. These symptoms are associated with dyspnea, dysphagia, and cognitive dysfunction as a result of cerebral venous hypertension. In these cases, patients must decide, along with their doctors, whether to undergo stent therapy or instead proceed with radiotherapy and chemotherapy.

Prior to SVC stent therapy, patients undergo bilateral arm venography to determine the site and degree of stenosis. Patients in whom the SVC is severely stenosed and the obstruction involves the confluence of the brachiocephalic veins may be candidates for stent therapy. Patients with very extensive total occlusions involving both SVC and subclavin veins may be referred to other therapy. Short occlusions can also be treated with thrombolysis and then stented.

Steps of the procedure: For preoperative relief of colon obstruction, the stent is placed across the acute obstruction, with the intent of decompressing and cleaning the colon, which may allow a single-stage procedure. In studies of stent treatment of colon cancer, successful stent placement is usually achieved in lesions of the sigmoidal colon, descending colon, and transverse colon. The stent delivery system is flexible and can be maneuvered into the transverse colon if necessary.

An expandable stent can effectively relieve symptoms. The rigid plastic tube stent, on the other hand, is shoved through the distal tumor with a pusher-tube device. Another type of expandable stent treatment is the self-expanding metal stent, which was first modified for esophageal use in 1991. One example is the Schneider Wallstent, which can be mounted onto a delivery catheter and held in check with a sheath.

Percutaneous access can be achieved via the right common femoral vein for SVC stent insertion. An angled guide wire is inserted, dilatation is achieved with a small balloon, and a self-expanding stent is inserted.

After the procedure: When appropriately placed, the duration of palliative stent therapy averages seventeen weeks and can extend as long as sixty-four weeks. Stent insertion is successful for most patients receiving treatment for SVC syndrome, with patients experiencing symptomatic relief within a few hours of the procedure. Few major complications are reported; most patients can start radiotherapy the next day after stenting. During the procedure, heparin is administered to prevent clotting.

Risks: Inserting a self-expanding metallic stent into an esophagojejunal anastomotic stricture can be a successful and uncomplicated therapy. The risks of palliative stent therapy for the treatment of colon cancer include migration in the colon with colonic motility. Especially when the stent is placed at an anatomical curve such as the splenic flexure, these stents are much more likely to migrate. Migration in the treatment of colon cancer occurs in about 20 percent of cases. Perforation can occur, although this outcome is often the result of balloon dilation performed before the stent is placed.

Results: Stent therapy to treat SVC syndrome usually allows patients to undertake an ideal radiotherapy course, which maximizes the quality and length of their lives. In the twenty-first century, advances have been made in stent therapy. Drug-eluting stents have been developed, which can deliver medications to a patient. Stents can also be coated with biological agents that promote faster healing. Bioresorbable stents, which can be 3D-printed, are made from iron- and zinc-based metals. A combination of these innovations can also be tailored to a patient’s specific needs and individualized treatment plans. 

Bibliography

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Lee, Dae-Hyun, and José M de la Torre Hernández. "The Newest Generation of Drug-eluting Stents and Beyond." European Cardiology Review, vol. 13, no. 1, 2018, pp. 54-59, doi:10.15420/ecr.2018:8:2.

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