Confocal Laser Endomicroscopy and Endoscopic Mucosal Resection
Condition: Barrett's Mucosa With High Grade Intraepithelial Neoplasia (HGIEN)
MeSH terms: Neoplasms; Barrett Esophagus
Study type: Interventional

Summary: 
      The accurate detection and therapy of adenocarcinoma originating from Barrett's oesophagus is
      challenging as current endoscopic techniques are unreliable for both the detection of high
      grade intraepithelial neoplasia (HGIN) within Barrett's mucosa and the correct measurement of
      the dimension of such neoplastic lesions. Confocal laser endomicroscopy (CLE) is a promising
      technology that could help to close this gap. Relying on first clinical trials of CLE, which
      showed remarkable results for the detection of Barrett's associated neoplasia, the
      investigators want to use CLE as targeting tool for endoscopic mucosal resection of HGIN in
      patients suffering from Barrett's oesophagus. CLE-mapping of neoplastic lesions will be
      documented and compared to the later performed histological evaluation of the resected
      specimen. If CLE is passing our challenge this will be another valuable proof of its high
      potential as reliable new endoscopic technology. Its usage could increase the en-bloc
      resection rate and decrease the amount of repetitive resections, which would remarkably
      improve the patients comfort.
    

Detailed description: 
      Introduction

      Barrett's oesophagus is a common complication in patients suffering from gastro-oesophageal
      reflux disease (GERD). By means of chronic acid exposure the squamous epithelium of the
      oesophagus turns into a specialised columnar epithelium (SCE) with goblet cells. This
      histological change is prevalent in 1% of the normal population, and in up to 4, 9% of
      patients with reflux symptoms [1]. Although the Barrett's epithelium itself does not
      necessarily cause additional symptoms, its presence has to be diagnosed accurately, since
      affected patients are at increased risk of 0.5% per year of developing Barrett's associated
      cancer. An important prognostic factor is made up by the grade of dysplasia within the
      Barrett's mucosa. While most patients with no dysplasia or low-grade dysplasia remain
      clinically inconspicuous, the annual risk of developing cancer is up to 10% in those patients
      with high-grade dysplasia. If a Barrett's associated neoplastic lesion is found during
      endoscopy, Barrett's associated cancer is also present at another site of Barrett's
      oesophagus in up to 30% [2].

      Consequently, they undergo periodically screening, consisting of endoscopy of the oesophagus
      with 4-quadrant biopsy every 2 to 3 cm or, in case of HGIN, local ablative therapy. The time
      period between controls depends on the grade of dysplasia diagnosed at upper gastrointestinal
      endoscopy. If no dysplasia is present, the recommended follow-up period is less than 5 years.
      In case of low grade dysplasia endoscopic controls should be performed every year. Patients
      with high grade dysplasia should be examined every 3 months or prepared for a therapeutic
      intervention [3].

      Early detection of Barrett's associated neoplasms, which can be histologically classified as
      adenocarcinoma, has important therapeutic implications. Cancerous infiltration of submucosal
      structures is associated with a significant risk of lymph node metastases and should be
      therefore treated by surgery. However, oesophagectomy has been shown to suffer from mortality
      rates between 3 and 12%, apart from substantial short- and long-term morbidity. Hence it is
      essential to detect early neoplastic lesions to have a broader range of therapeutic options
      at disposal. Patients with high grade intraepithelial neoplasia (HGIN) or mucosal cancer are
      perfect candidates for curative endoscopic interventions like endoscopic ablation (with
      radiofrequency, for example), endoscopic submucosal dissection (ESD) or endoscopic mucosal
      resection (EMR). The latter techniques are preferred as the resected specimens can be
      evaluated histologically, which provides definite information about the invasion depth and
      whether the resection borders are free from neoplastic tissue. Because of high rates of newly
      occurring neoplasia, remaining areas of Barrett's mucosa should be ablated or resected after
      histological confirmation of Barrett's oesophagus associated neoplasia [3, 4].

      Trying to improve the diagnostic yield in the surveillance of patients with high risk for
      Barrett's oesophagus associated neoplasia, many new endoscopic inventions have been
      introduced into the management of Barrett's oesophagus in order to optimize the detection
      rates of early lesions. Among those are developments that improved the image quality of
      conventional white light endoscopes like high-resolution and high-definition endoscopes.
      Another approach, called chromoendoscopy, uses in vivo staining with methylene blue, indigo
      carmine or acetic acid. These dyes help to increase the tissue contrast which leads to
      improvement of detection rates comparable to high-resolution endoscopy. High contrast levels
      without staining agents can be achieved by the use of narrow band imaging (NBI). This
      technology additionally improves the visibility of capillaries, veins and other subtle tissue
      structures by the use of light with wavelength restricted to small bands in the blue and
      green spectrum. In a prospective randomized crossover study it showed equal results to
      high-resolution endoscopy plus indigo carmine [4, 5].

      The newest development that has been introduced in the endoscopic management of the
      gastrointestinal tract is the so called confocal laser endomicroscope (CLE). Confocal
      microscopy was developed by Marvin Minsky in the late 1950s. Its principle is the microscopic
      scanning of focal points below the surface of an object. In comparison to conventional light
      microscopy it uses a special filter system to avoid image overlapping by surrounding tissue.
      In detail, a light source (normally a laser) is focused by a microscope objective lens to a
      diffraction limited spot on or inside the object. Light that is scattered, or fluorescence
      excited (achieved through fluorescein staining, for example) and emitted, at the focus in the
      sample will partially return back through the optics along the path from which it arrived. A
      beam-splitter placed into the path reflects the return light towards a detector. The optics
      will focus the light from the focal point in the specimen to its conjugate focus near the
      detector (hence the technology is termed "con-focal"). Here a spatial filter ("pinhole") is
      used to extinguish all light deriving from areas outside the focal point. Light reflections
      from the focal point itself will be forwarded to the detector which is connected to a
      computer system that digitalises the optical signal and creates the in vivo histological
      image [6].

      Focussing on its clinical impact, confocal microscopy is the first technique to allow in vivo
      evaluation of tissue structures beneath their surface. Because of many breakthroughs in
      miniaturisation (mostly in the 1990s) this technology could be applied for intraluminal use
      in gastroenterology, integrated into a otherwise standard endoscope. It allows the in vivo
      histological visualisation of the upper 250 micrometers of all walls within the
      gastrointestinal tract, additionally to the normal function of white light endoscopy
      (provided by two separate screens on top of the workstation) [6].

      Using CLE in a first clinical approach, Kiesslich et al. found high sensitivity and
      specificity rates for the detection of Barrett's oesophagus as well as for the prediction of
      Barrett's associated neoplastic changes - for both results CLE derived pictures were compared
      to conventional histology [7]. In a first prospective, randomized, double-blind, controlled,
      crossover trial Dunbar et al. proved these findings, as CLE-targeted biopsies had a higher
      diagnostic yield for Barrett's oesophagus associated neoplasia than standard endoscopy with
      4-quadrant random biopsy [8].

      Study Aims

      In our clinical investigation we want to use confocal laser endomicroscopy (CLE) to
      accurately target Barrett's oesophagus associated neoplasia for subsequent endoscopic mucosal
      resection (EMR). To our knowledge this combination is only documented in one case report so
      far, describing the successful resection of a high-grade dysplastic Barrett-segment by the
      use of CLE-targeted EMR [9].

      We want to show that CLE is suitable to detect the exact borders of high grade
      intraepithelial neoplasia. In our experience this feasibility cannot be reliably provided by
      any other established technique like chromoendoscopy or narrow band imaging, which often
      causes the need for re-treatment or even surgery.

      To guarantee accurate documentation of mucosal CLE-mapping, the dimensions of the neoplastic
      lesion will be marked in terms of colour, photographed by simultaneously available white
      light endoscopy and finally evaluated by histological assessment of the specimen. Analysing
      the borders of the resected specimen in concern of tumour infiltration we will be able to
      calculate the en-bloc resection rate of CLE-targeted EMR.

      In order to evaluate CLE concerning true negative results we will resect all remaining
      mucosal areas affected by Barrett within the second phase of the examination or (if the
      lesions are too big for one-time resection) within a second examination. Once again, CLE will
      be applied for all lesions to search for malignancies. If CLE detects further areas of
      neoplasia, CLE-mapping as mentioned above will be performed. All resected tissue parts will
      be evaluated histologically to check the results of CLE.

      If CLE provides reliable data in our investigation this would be a big step on the way to
      establishing this new technology within the pre-interventional endoscopic management of
      patients suffering from Barrett's oesophagus. This could help to increase the en-bloc
      resection rate, decrease the amount of repetitive resections and consequentially improve the
      patients comfort.

      Study Design

      Prospective clinical trial without randomisation or blinding

      Study Population

      Patients referred to our department for endoscopic mucosal resection (EMR) of Barrett's
      mucosa with high grade intraepithelial neoplasia (HGIN) that has been detected during routine
      upper endoscopy or Barrett's surveillance endoscopy at our department or at another hospital.

      Exclusion criteria:

        -  patients allergic to one of the drug components (including drugs used for conscious
           sedation like propofol or midazolam as well as fluorescein, the fluorescent dye used for
           CLE )

        -  patients presenting with contraindications to EMR (low platelet count, therapeutic
           anticoagulation, coagulation disorders)

        -  refusal to participate in the study

      Methods

      Our investigation will be performed at the Medical University of Vienna, department of
      medicine III, clinical division of gastroenterology and hepatology. Patient recruitment will
      start on the 1st of July 2010. The study will last for two years. The number of patients
      included within this period will be 40, based on the current number of EMR performed at our
      department for Barrett's with intraepithelial neoplasia.

      All patients who fulfil the listed inclusion criteria, will receive the patient information
      form of this study together with the usual informed consent form of the respective endoscopic
      examination they are about to undergo. Patient information will be done at least 24 hrs.
      before the intervention, as practised at our unit. If the patient agrees to participate in
      the study he will be prepared for endoscopy with our confocal laser endomicroscope (Pentax
      EC3870K with the ISC-1000 confocal endomicroscopy processor - Pentax, Tokyo, Japan and
      Optiscan Pty Ltd, Notting Hill, Victoria, Australia) by administration of intravenous
      propofol and/or midazolam as routinely used for conscious sedation during endoscopic
      procedures at our department. Additionally, 5-10 ml of a 10% solution of fluorescein sodium
      will be administered intravenously to enhance tissue fluorescence during endomicroscopy.

      All drugs will be administered by medical specialists (such as the project director),
      assistant doctors (such as the project assistant) or registered nurses, as routinely
      practised at our institution.

      Ethical implications

      Confocal laser endomicroscopy is a safe new technique that has already been studied in
      clinical trials [7, 8]. Its safety is being guaranteed by the use of low intensity laser
      light that can at worst cause local bleaching of fluorescein containing cells, which is
      harmless, reversible and even used as diagnostic sign in experimental conditions [6].

      Endoscopic mucosal resection is a well established technique for the minimal invasive,
      non-surgical curative treatment of intramucosal neoplasia. It has been studied in many
      clinical trials and is routinely performed at our unit for lesions in the oesoophagus, the
      stomach, duodenum and colo-rectum. Although severe complications like prolonged bleeding or
      perforations can potentially occur, the risk/benefit profile of this procedure is very good,
      compared to surgical treatments of neoplastic diseases of the oesophagus [10].

      This study protocol has been submitted to the ethic commission of the Medical University of
      Vienna (EK-Nr. 697/2009) and was handled at the meeting on the 8th of September 2009. A
      positive vote was already delivered to our institution in written form.
    

Intervention name(s): Endoscopic mucosal resection
Intervention type(s): Procedure
Intervention description(s): Confocal laser endomicroscopy will be used to target endoscopic mucosal resection of Barrett's oesophagus-associated neoplasia
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Barrett's oesophagus; High grade intraepithelial neoplasia (HGIEN)