EsophageAl mulTisegmented fully covERed self-expandable metal Stent for malignant strictures: a Safety and Feasibility study

The majority of esophageal cancer patients have unresectable disease at
presentation. Even after curative therapy, about 20% of patients develop
dysphagia from recurrent strictures. Dysphagia is the predominant symptom in
70% of esophageal cancer. Complications include high risk of aspiration and
reduced patency of the orogastric pathway, which lead to a profound reduction
in quality of life. Therefore palliative therapy has been, and will continue to
remain, an important part of the management of esophageal malignancy. The
primary goal of palliative treatment in patients with esophageal cancer is to
achieve adequate improvement of dysphagia and therefore quality of life, with a
reduced need for additional interventions.
Although optimal intervention for treatment of dysphagia has yet to be
established, placement of a partially or fully covered self-expandable metal
stents (SEMS) is the palliative modality of choice and recommended by the
European Society of Gastrointestinal Endoscopy2. This because of their ability
to provide instant, long-lasting relief from dysphagia with minimal morbidity
and negligible mortality3.

1st generation SEMS: Uncovered SEMS
The first commercially produced self-expandable metal stent was the Wallstent,
made of stainless steel. Ultraflex stent, developed by Boston Scientific
(Natick, MA, USA) was the first stent to be made of nitinol, a shape-retaining
nickel and titanium alloy. Since then, nitinol is most popular stent wire
material.

2nd generation SEMS: Covered SEMS
To prevent tumor ingrowth into stent, fully or partially covered stent is
introduced in 1990. Covered material is various: Polyurethane, silicone and
PTFE.

3rd generation SEMS: Retrievable SEMS
A retrievable fully covered SEMS is introduced in 1997. Drawstrings were
attached to stent to help remove or reposition the stent.

4th generation: Self-Expandable Plastic Stent
Polyflex is the first self-expanding plastic stent (SEPS) characterized by
removability.

Known complications of esophageal stent placement are esophageal perforation,
chest pain, bleeding, fistula formation, gastroesophageal reflux and recurrent
dysphagia due to among others tumor/hyperplastic tissue in- or overgrowth,
stent migration or food occlusion. Stent migration rates of 6-17% have been
described4. Migration rates seem to be higher when using fully covered stent
designs, possibly due to reduced adhesion and fixation to the esophageal wall.

The esophageal multisegmented fully covered SEMS is made of nitinol wire and
has a silicone cover. It shares similar characteristics with other 2nd and 3rd
generation stents which have been used over more than 20 years. Placement is
done according to the over-the-wire (OTW) method using fluoroscopic images to
control the position, which is considered to be a safe method and is widely
used in daily clinical practice5-6. Its multisegmented design is a new aspect
and expected to decrease migration rates. The multisegmented fully covered SEMS
has been evaluated for palliation of malignant dysphagia and has been approved
with a Conformité Européenne (CE) certificate for the maintenance of esophageal
lumen patency in malignant dysphagia.

Since there is limited data on the effectiveness in the clinical context, the
aim of this study is to evaluate the safety and efficacy of the esophageal
multisegmented fully covered SEMS. We will pay specific attention to migration
rates during assessment of the safety of the stent.

The main objective of this study is to evaluate the safety, including stent
migration rates, and efficacy of placement of the esophageal multisegmented
fully covered SEMS with the OTW method in patients with non-operable malignant
obstruction of the esophagus or esophagogastric junction, extrinsic malignant
compression, or recurrent malignant dysphagia after esophagectomy.

Other (secondary) objectives are to assess the effect of the stent on the
presence of hyperplastic reaction after implantation, the functional
complications and survival.

A non-randomized prospective clinical study in a single centre (Radboudumc), to
evaluate the safety and efficacy of the esophageal multisegmented fully covered
SEMS in patients with non-operable malignant obstruction of the esophagus or
esophagogastric junction, extrinsic malignant compression, or recurrent
malignant dysphagia after esophagectomy.

After stent placement patients will be evaluated with a telephone interview 14
days later and at 4-week intervals until death/stent removal , or until a
maximum of 6 months follow-up.

Placement of esophageal multisegmented fully covered SEMS

Participation in the study does not cause any additional charge to patients.
The stent implantation and follow-up are not different from the usual in
standard clinical practice. As the stent is designed to prevent migration, this
could be a possible advantage of participation in the study. However, a
decrease of migration rates has to be confirmed first.

The risk classification is determined as negligible based on the guideline of
the *Nederlandse Federatie van Universitair Medische Centra*. The risks
associated with the participation in the study are similar to the risks of
treatment with any esophageal stent, and do not different from the
complications arising from the use of other expandable stent; migration,
bleeding, perforation and development of hyperplasia/granulation tissue.