Endobronchial Brachytherapy Stent

1
Endobronchial Brachytherapy Stent
Farshid Firoozbakht, MD, MPH1 David Duhamel,
MD2 Derick Hanlan, MD2 John Feigert, MD2.
1Department of Internal Medicine, Georgetown
University Hospital, Washington, D.C. . 2Virginia
Hospital Center Pulmonary Special Procedures
Unit, Arlington, VA .
Abstract
Methods
Discussion
The combination of treatment modalities to
treat our patients airway obstruction proved
successful. The addition of the endobronchial
brachytherapy stent made the delivery of
brachytherapy both more effective in treatment of
the tumor mass and safer by reducing
unintentional exposure of high-dose radiation to
normal tissue. As with other silicone stents,
the endobronchial brachytherapy stent can be
placed securely within the airway. The use of
the endobronchial brachytherapy stent has the
advantage of being easily repositioned,
exchanged, or removed.10 The stent may be
removed at the conclusion of the brachytherapy
sessions or remain in place if it is of benefit
for airway patency. The use of an algorithm
designed to direct combinations of treatment
modalities to increase airway patency by reducing
tumor mass has been employed successfully in a
series of patients a the University of Washington
Medical Center in Seattle. The patient group
studied presented with symptoms of airway
obstruction. Treatment modalities in the
algorithm included dilation, core-out of tumor,
laser ablation, stenting, and high-dose
brachytherapy.10 The addition of our
endobronchial brachytherapy stent would combine
and enhance the stenting and high-dose
brachytherapy of this algorithmic approach for
the treatment of airway obstruction. There
are disadvantages to the use of brachytherapy.
Relative contraindications to endobronchial
brachytherapy are malignancies causing erosive or
penetrating lesions and extrinsic compression of
the airway by large mediastinal node masses.14
In comparison to other treatment modalities,
brachytherapy requires a multidisciplinary team
and special equipment which may not be available
at all medical centers. Brachytherapy also has a
delayed response time when compared with other
treatments.14 There have been serious
complications with the use of endobronchial
brachytherapy. Of these, massive hemoptysis and
fistula formation to the mediastinum were the two
most serious.11 The use of airway stents
also has disadvantages. Relative
contraindications include high tracheal lesions
and patients with long life expectancy. The
insertion of most airway stents requires
placement via rigid bronchoscopy. The use of
airway stents is limited to placement in more
proximal mainstem bronchi.14 Silicone stents
carry the risk of stent migration. The proper
selection of both the length and width are
necessary to ensure a secure fit and to prevent
the obstruction of peripheral bronchi. Recurrent
obstruction of stents is the most serious
complication. Obstruction can be caused by tumor
overgrowth or by granulation tissue formation.2
With the conclusion of the calculated
brachytherapy sessions, studies have found that
75 of patients reported palliation of their
symptoms.7 Studies involving patients with
primary bronchial carcinoma showed that the
reduction of obstruction caused by tumor lead to
significant improvement in the following
measures ventilation and perfusion, spirometry,
and six minute walk distance.8 Objectively, the
best measure of treatment efficacy is with direct
visualization of tumor regression via flexible
fiberoptic bronchoscopy.7
Brachytherapy has long been used for the
palliative treatment of airway obstruction caused
by endobronchial tumors. The precise
administration of this therapy has often been
limited, however, by potential movement of the
delivery catheter prior to radiation source
placement. We describe a new airway
brachytherapy stent, designed to allow more
precise delivery of brachytherapy adjacent to
airway tumors. This brachytherapy stent is made
of silicone and is designed with ten channels,
each with a diameter large enough to allow
insertion of the brachytherapy catheter. After
laser therapy and mechanical debridement with a
rigid bronchoscope to debulk the tumor, the stent
is then deployed to overly the remaining tumor
bed. Then, for each brachytherapy session, the
brachytherapy catheter is guided via flexible
fiberoptic bronchoscopy to the stent channel that
is closest to the tumor mass. By enabling the
brachytherapy to be deliveredand remain adjacent
tothe tumor mass, this stent minimizes the
potential effects of radiation on normal
bronchial tissue and maximizes the delivery of
radiation to the tumor mass. The stent may be
removed at the conclusion of the brachytherapy
sessions, or remain in place if it is of benefit
for maintaining airway patency. We describe our
experiences with this device, and discuss
potential uses and limitations of this novel
instrument for the delivery of brachytherapy for
endobronchial malignancies.

• The endobronchial brachytherapy stent is
  made of silicone, designed with ten channels, the
  diameter of each of these channels is large
  enough to pass the afterloading catheter through.
  The stent was manufactured by Hood
  Laboratories.
• Prior to the stent placement, a combination
  of laser therapy and mechanical debridement with
  the rigid bronchoscope is employed in an effort
  to debulk the tumor mass. The type of laser used
  is the NdYAG laser. For endobronchial
  obstruction, the laser is primarily used as a
  coagulator due to its ability to cause
  hemostasis. With achievement of hemostasis, the
  tumor tissue can then be mechanically debulked
  with the rigid bronchoscope itself or the use of
  forceps.5
• The stent is then deployed via rigid
  bronchoscopy to overly the tumor bed which has
  been debulked. Confirmation of the stent
  placement in its intended location can be done
  with flexible bronchoscopoy prior to the
  placement of the afterloading catheter.
• Prior to each of the brachytherapy sessions,
  the afterloading catheter is guided through one
  of the channels that is adjacent to the tumor bed
  via flexible bronchoscopy. The afterloading
  catheter is then taped to the patients nose.
  The location of the afterloading catheter can be
  confirmend with flexible bronchoscopy.
• The patient is then transported to the
  brachytherapy room which contains the high-dose
  radiation afterloading device. The afterloading
  catheter is attached to the afterloading device
  containing the radioactive source.8
  Brachytherapy is delivered in accordance the
  calculations of the radiation oncologist. The
  entire brachytherapy session is monitored from an
  adjacent shielded room with closed circuit
  television.8 Upon completion of the
  brachytherapy session, the afterloading catheter
  is then removed.
• The patient may receive multiple treatments
  of brachytherapy over an extended period of time
  depending on the treatment goals of the
  pulmonologist, oncologist, and radiation
  oncologist.4

Rigid and Flexible Bronchoscopic Images
Image 2 Mid-tracheal tumor mass post laser
coagulation therapy via rigid bronchoscopy.
Image 1 Initial obstructing mid-tracheal tumor
mass visualized by rigid bronchoscopy.
Image 4 Endobronchial brachytherapy stent
deployed via rigid bronchoscopy to overly
mid-tracheal tumor bed. All ten catheter
channels are well-visualized and patent.
Image 3 Mid-tracheal tumor bed remaining after
mechanical debridement of coagulated tumor mass.
Introduction
Tumor development and metastases can often
involve growth and subsequent obstruction of the
tracheal and bronchial lumen.8 Obstruction of
the tracheal or bronchial lumen can have many
consequences. This can lead to airway
obstruction and symptoms of dyspnea or stridor.
The obstruction can also impede normal airway
clearing mechanisms which can result in
postobstructive infection. The decrease in
ventilation caused by the obstruction can
ultimately result in atelectasis or complete
collapse of the lung caused by changes in the
ventilation-perfusion ratio.8 Methods to
treat the obstruction of the airways can lead to
palliation of symptoms such as dyspnea and
stridor.3 Treating airway obstruction also can
decrease risk of lung infection and lead to
re-expansion of atelectatic lung.8 Many
modalities exist to treat airway obstruction
caused by tumor growth, examples include
mechanical debridement, laser therapy, airway
stent placement, and brachytherapy. In this
paper we discuss the use of a combination of the
above treatment modalities with the addition of a
novel airway stent designed specifically for
endobronchial brachytherapy with the ultimate
goal for palliative treatment of airway tumors.
Brachytherapy involves the placement of an
encapsulated radioactive source via an
afterloading device adjacent to the tumor growth
in the trachea or bronchus which is causing
airway obstruction.1 The use of brachytherapy is
largely used for the palliation of symptoms
caused by airway obstruction from a tumor. The
technique currently employed for the placement of
the afterloading polyethylene (brachytherapy)
catheter involves the use of a flexible
fiberoptic bronchoscope to guide the catheter
into the airway and place the catheter adjacent
to the tumor.1 This technique employed for the
placement of the afterloading catheter carries
the constant risk of movement of the afterloading
catheter from its intended location.
Unintentional movement of the afterloading
catheter has the potential to be harmful to the
patient by causing exposure of high-dose
radiation to normal tissue in the airway and
minimizing the effects of high-dose radiation on
the intended target of tumor mass. We have
developed a specific endobronchial brachytherapy
stent to minimize the potential effects of
radiation on normal bronchial tissue and maximize
the delivery of radiation to the tumor mass. The
stent is made of silicone, designed with ten
channels, the diameter of each of these channels
is large enough to pass the afterloading catheter
through. With the afterloading catheter more
securely in place in one of the stent channels,
the risk of catheter movement and subsequent
adverse outcomes is substantially decreased.
The stent itself also serves to maintain airway
patency.2 We used this novel airway stent in
combination with brachytherapy to achieve
significant palliation of symptoms in a patient
with metastatic tracheal and bronchial tumor
masses who presented with significant dyspnea and
stridor.
Conclusions
The use of the endobronchial brachytherapy stent
has been shown to be effective as an adjunct to
brachytherapy in our patient. In order to fully
appreciate its benefits and limitations, we need
to continue the use of this stent as an adjunct
to brachytherapy in the palliative treatment of
patients with obstruction of airways caused by
malignancy.
Image 5 Position of stent reconfirmed via
flexible fiberoptic bronchoscopy.
Image 6 Afterloading catheter placed through the
channel adjacent to the tumor bed.
Results
The endobronchial brachytherapy stent has been
used in a single patient thus far. The goal of
brachytherapy in this patient was that of
palliation of symptoms of dyspnea and stridor.
This goal was achieved as determined subjectively
by the patient stating signifcant relief of
symptoms and objectively by visualization of
improved airway patency and decreased tumor
burden in the trachea and bronchus. The patient
tolerated the procedure of stent placment with no
complications occurring. The procedure of stent
placement was comprised of tumor debulking
using the NdYAG laser and mechanical debridement
with a rigid bronchoscope, then placement of the
endobronchial brachytherapy stent. Prior to each
brachytherapy session, the patient tolerated the
placement of the afterloading catheter via
flexible bronchoscopy with no complications. The
afterloading catheter remained in place with no
movement during each brachytherapy session. The
patient underwent three sessions of brachytherapy
with no complications. The endobronchial
brachytherapy stent was left in place after the
completion of all of the brachytherapy treatment
as the patient benefited from the improved airway
patency provided by the stent. Flexible
bronchoscopy showed dramatically decreased tumor
burden with each successive brachytherapy
session. The surrounding normal healthy
endobronchial tissue was unaffected by the
high-dose radiation received during the
brachytherapy sessions. There was no stent
migration seen via flexible bronchoscopy.
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