The choice of stent is influenced by a variety of factors, including tumor length and position, and presence of a fistula and personal preference of the endoscopist.
* Stents could be made of plastic or metal
* Stents could be covered or non covered
* Stents could be proximal or distal release
* Stents could be removable or non removable
* Stents with or without an antireflux device
Features
* Uncovered stents have the disadvantage of obstruction by tumor in-growth across the mesh. The drawback of covered stents is the risk of migration. Thus, uncovered stents are preferred for tumours at the cardia, as they are less likely to migrate. Covered stents are preferred for tumours with a high risk of fistula formation or when a fistula already exists.
* Proximal release stents (i.e. stents opens from proximal to distal) are used in obstruction in proximal cervical oesophagus to ensure accurate placement. A placement that is too proximal may result in choking and/or aspiration. The patient may also feel an intolerable foreign body sensation especially if encroachment on to the cricopharyngeus occurs.
* Removal oesophageal stents are used for oesophageal leaks and fistula management. The stent is removed once the leak or the fistula heals. Removal stents are also used for benign strictures. Removal stents could be metallic or non metallic (plastic)
* A stent deployed across the gastroesophageal junction leads to gastroesophageal reflux in most patients, causing significant morbidity. Stents with an antireflux valve could be used to reduce morbidity. Stents with an antireflux function are Dua stent (Wilson-Cook Medical)- it has a “windsock”-type valve; a modified Choo stent (M.I.Tech) with a long inner antireflux valve; and the Bonastent (Standard Sci-Tech)
Commercially available oesophageal self-expanding metal stents (SEMSs) include:
- Ultraflex (Microvasive, Boston Scientific, USA)
- Z-stent (Wilson-Cook Medical,USA)
- Polyflex (Boston Scientific)
- Bonastent (Standard Sci-Tech, Korea)
- Choo stent (M.I.Tech, Korea)
- Niti-S stent (TaeWoong Medical, Korea).
All stents appear to be equally effective in palliating obstructive symptoms.
Ultraflex stents are popular in Europe. The last 2 cms of ultraflex stent are not covered. This helps embed the stent more firmly and reduce the risk of migration.
Currently, there is no consensus on absolute contraindications for oesophageal SEMS placement, but careful patient selection is of utmost importance. Patients with a short life expectancy (less than 4 weeks), multiple metastatic disease, or peritoneal seeding should probably not be considered as candidates.
