Max Almond

TOWARDS REAL-TIME 'BIOCHEMICAL ENDOSCOPY' FOR DIAGNOSIS OF EARLY BARRETT'S NEOPLASIA

Introduction Raman spectroscopy is a powerful analytical technique that can rapidly and accurately identify biochemical changes in cells that have become neoplastic. We aim to transfer this laboratory based technique to the bedside in order to identify high-grade dysplasia and early malignant change within Barretts oesophagus. Here we demonstrate the feasibility of a novel fibre-optic Raman probe to map the pathology encountered in a resected human distal oesophagus. Methods A novel Raman probe1 2 designed to fit through the 2.8 mm instrument channel of a standard endoscope was used to map a distal oesophagus ex vivo. Following Ivor-Lewis oesophagectomy (with curative intent in patients with oesophageal adenocarcinoma), a reproducible mapping grid was placed over the distal oesophagus and Raman spectra were measured at specified grid positions using 1 and 5 s acquisition times (Figure 1). A monochromatic 830 nm laser was used for excitation and a Renishaw system 100 spectrometer for the measurement of Raman spectra. Figure 1 PWE-093 Mapping of a distal oesophagus using a perspex grid for probe positioning Results Laboratory based Raman systems can delineate eight pathological groups in the distal oesophagus with sensitivities between 73% and 100%.3 To date we have measured 76 spectra from 3 oesophageal specimens using the novel endoscopic probe and data collection and analysis is currently on-going (Figure 2). Histopathological diagnosis has been confirmed by expert pathologists following point biopsy at each grid position in order to correlate the Raman signal with the gold standard. Multivariate analysis will be used to extract subtle spectral features to evaluate the accuracy of the probe for delineating between pathological groups. Figure 2 PWE-093 Example mean Raman probe spectra measured on normal squamous, Barretts and neoplastic oesophageal tissue Conclusion Further data collection (currently on-going) is needed to generate a robust classification algorithm in order to delineate between Barretts metaplasia, low/high-grade dysplasia and cancer in the distal oesophagus. Preliminary spectra obtained using a novel endoscopic probe are consistent with laboratory data and suggest profound potential for in vivo endoscopic diagnosis using Raman spectroscopy.

PTU-198 Towards objective endoscopic diagnosis of early Barrett's neoplasia using fibre-optic Raman spectroscopy

Introduction Raman spectroscopy is a powerful analytical technique that can rapidly and accurately identify biochemical changes in cells that have become neoplastic. We are aiming to translate this laboratory technique into an endoscopic tool that can identify high-grade dysplasia (HGD) and early malignant change (T1a, T1sm1) within Barretts oesophagus. Here we aim to demonstrate that a novel fibre-optic Raman probe can correctly classify the pathology of ex vivo oesophageal tissue. Methods A custom-built Raman probe, designed to fit through the instrument channel of a standard endoscope, was used to measure Raman spectra from ex vivo oesophageal tissue following oesophagectomy, endoscopic resection, or point biopsy from patients with Barretts oesophagus +/- neoplasia. 1s spectra were measured using a monochromatic 830 nm laser for excitation. Multivariate analysis was used to correlate Raman spectra with histopathological diagnosis and calculate probe accuracy. Results 348 spectra were measured from ex vivo tissue from 28 patients. Fibre-optic Raman measurements were able to discriminate between HGD/adenocarcinoma and non-dysplastic Barretts oesophagus (BO) with a sensitivity of 91% and specificity of 96%. Conclusion Fibre-optic Raman Spectroscopy could enable endoscopic targeting of early neoplastic lesions in the oesophagus facilitating potentially curative endoscopic resection. Preparation is underway for an in vivo pilot study. Competing interests None declared.

The future developments in upper GI cancer

The ageing population and changes in incidence of upper gastrointestinal cancer will have profound changes for our management of these patients. There is much debate as how to bring forward the diagnosis of early mucosal cancer that may be curable using endoscopy or by surgery. In the older more frail patients, early disease will often be controlled by endoscopic resection and ablation therapy.

PTH-140 Dual modality endoscopic therapy for barrett’s-associated oesophageal dysplasia in a tertiary referral centre: completing the audit cycle

Introduction The efficacy of dual modality endotherapy with endoscopic resection and mucosal ablation is now well documented in the treatment of Barrett’s-associated early neoplasia. This strategy was supported by a consensus survey of international experts in 2011 with the aim of achieving high rates of complete eradication of dysplasia and intestinal metaplasia (CE-D and CE-IM).1 This re-audit of clinical practice in a single tertiary oesophagogastric unit aimed to assess whether patients with Barrett’s-associated early neoplasia received dual modality endoscopic therapy in order to achieve CE-D and CE-IM. Method In 2011 an audit standard was defined recommending that patients with early glandular neoplasia (high-grade dysplasia (HGD) +/- intramucosal cancer (IMC)) should receive dual modality endoscopic therapy aiming for CE-IM. In the initial audit phase a prospectively maintained database was interrogated between 2004–2011 in order to assess current practice. Changes in practice were implemented following in-house presentation to the oesophagogastric MDT in 2011, and practice and outcomes between 2012–2014 were re-audited. Results The initial audit included 72 patients with a median follow-up of 38 months treated by ER +/- ablative therapy with curative intent for HGD (88%) or IMC (12%). The re-audit included 43 patients: LGD 2 (5%), HGD 31 (72%) and IMC 10 (23%), with a median follow-up was 21 months. The use of ablation therapy post-ER was higher in the re-audit group (86% vs 60%; p = 0.003). Rates of CE-D and CE-IM were also higher in the re-audit group (79% vs. 29%; p < 0.001) and (28% vs. 1%; p < 0.001) respectively. Disease progression to invasive cancer (at least T1b) appeared lower in the re-audit group although did not achieve statistical significance (2% Vs. 11%; p = 0.150). Conclusion This completed audit cycle demonstrated that use of dual modality endoscopic therapy has increased since 2011. This was associated with higher CE-IM and CE-D rates. Regular audit and re-audit can improve outcomes in patients receiving endoscopic therapy for early Barrett’s-associated neoplasia. Disclosure of interest None Declared. Reference Bennett C, Vakil N, Bergman J, et al. Consensus statements for management of Barrett’s dysplasia and early-stage esophageal adenocarcinoma, based on a Delphi process. Gastroenterology. 2012;143(2):336–46

PTU-168 Barrett’s Oesophagus Screening: Infrared Spectroscopy For Cytological Assessment

Introduction Screening for Barrett’s oesophagus could allow early detection, enabling timely diagnosis and intervention for oesophageal adenocarcinoma. Recent studies have shown the acceptability of a swallowed cytology brush (‘Cytosponge’) for cell collection. If introduced, cytological assessment would pose several challenges. Firstly, oesophageal cytology is performed infrequently, and expertise in this field is correspondingly limited. Secondly, assessment of individual cells is challenging even for experienced cytopathologists, with a degree of interobserver variability. Thirdly, screening would require a great deal of cytopathology resources. Infrared spectroscopy (IR) gives reproducible spectra based on cell biochemistry; applying multivariate statistical analysis and computer modelling can provide robust and rapid discrimination between pathological cell subtypes. We aimed to demonstrate the potential application of IR in analysis of oesophageal cytology. Methods Endoscopic cytology brushes were used to collect oesophageal cells from patients undergoing endoscopy for Barrett’s oesophagus. Cells were fixed in formalin, centrifuged and slides prepared. IR spectra were measured across the entire sample area. Pre-processing steps allowed spectra from individual cells to be reconstituted. Further pre-processing removed confounding effects and enhanced signal-to-noise ratios. Conventional cytology analysis was undertaken to provide a reference for developing a predictive model using IR data. Chemometric analysis was then undertaken using Partial Least Squares Discriminant Analysis (PLS1DA) and cross-validation performed. Results 23 cytology brush samples were collected from 11 patients. 4 samples contained low cell counts and were excluded from analysis. 5536 cells (2339 normal squamous, 2511 Barrett’s oesophagus and 686 dysplastic) were used to create and validate a predictive model. The predictive capability of the model is shown in the table below: Abstract PTU-168 Table 1 Normal squamous Barretts oesoph. Dysplasia Sensitivity 100% 1% 96% 2% 94% 3% Specificity 99% 1% 99% 1% 98% 1% Conclusion The high accuracy demonstrated by our predictive model suggests IR is a promising candidate for cytological analysis of oesophageal cells. As an objective, automated system, this technique could prove invaluable for Barrett’s screening in future. Reference Schubert JM et al. Lab Invest. 2010;90(7):1068–1077 Disclosure of Interest None Declared.

CHAPTER 8:The Prospects for Real‐Time Raman Spectroscopy for Oesophageal Neoplasia

Raman spectroscopy can provide exquisite sensitivity for molecular analysis of degenerating pre malignant changes in the oesophagus. We are interested in the prospect of rapid endoscopic diagnosis during endoscopy using Raman. The early changes of dysplasia are invisible to white‐light inspection. If detected, the dysplastic area can then be immediately removed and the surrounding area treated. The problem has been that histopathological classification, which is very challenging in these very early abnormalities. We have built prognostic models to classify these areas of abnormality and related the spectral classification to the patient prognosis and development of invasive cancer. The hypothesis is that the Raman signature allows biochemical detection at a biochemical and molecular level prior to morphological changes within the tissue. It is becoming clear that the dependence on the histological appearance of cells to establish a diagnosis of these early changes is subject to great variation and can be highly subjective. In addition, pathological analysis of tissue is very time consuming, expensive, and requires tissue biopsy. Kerkhof et al. demonstrated a poor level of interobserver agreement between expert histopathologists (K=0.58) in the grading of low‐grade (LGD) and high‐grade (HGD) oesophageal dysplasia. This distinction has vital consequences for patient management as LGD can be monitored by serial surveillance endoscopy, whereas HGD necessitates early endoscopic therapy or even surgery, and carries a significant risk of malignant progression. As well as being difficult to classify histologically, dysplasia can be extremely difficult or even impossible to recognise at endoscopy. Raman spectroscopy (RS) could remove the subjectivity from the histopathological assessment by measuring precise biochemical information about the target tissue. A Raman fibre‐optic probe could also enable real‐time diagnosis facilitating immediate treatment of suspicious areas of tissue during endoscopy, and could be used as a surgical adjunct.