Search

Endoscopic resection (ER) is an important diagnostic step in management of patients with early Barrett’s esophagus (BE) neoplasia. Based on ER specimens, an accurate histological diagnosis can be made, which guides further treatment. Based on depth of tumor invasion, differentiation grade, lymphovascular invasion, and margin status, the risk of lymph node metastases and local recurrence is judged to be low enough to justify endoscopic management, or high enough to warrant invasive surgical esophagectomy. Adequate assessment of these histological risk factors is therefore of the utmost importance. Aim of this study was to assess pathologist concordance on these histological features on ER specimens and evaluate causes of discrepancy. Of 62 challenging ER cases, one representative H&E slide and matching desmin and endothelial marker were digitalized and independently assessed by 13 dedicated GI pathologists from 8 Dutch BE expert centers, using an online assessment module. For each histological feature, concordance and discordance were calculated. Clinically relevant discordances were observed for all criteria. Grouping depth of invasion categories according to expanded endoscopic treatment criteria (T1a and T1sm1 vs. T1sm2/3), ≥1 pathologist was discrepant in 21% of cases, increasing to 45% when grouping diagnoses according to the traditional T1a versus T1b classification. For differentiation grade, lymphovascular invasion, and margin status, discordances were substantial with 27%, 42%, and 32% of cases having ≥1 discrepant pathologist, respectively. In conclusion, histological assessment of ER specimens of early BE cancer by dedicated GI pathologists shows significant discordances for all relevant histological features. We present propositions to improve definitions of diagnostic criteria.

Volumetric laser endomicroscopy (VLE) has been shown to improve detection of early neoplasia in Barrett’s esophagus (BE). However, diagnostic performance using histopathology-correlated VLE regions of interest (ROIs) has not been adequately studied. We evaluated the diagnostic accuracy of VLE assessors for identification of early BE neoplasia in histopathology-correlated VLE ROIs. In total, 191 ROIs (120 nondysplastic and 71 neoplastic) from 50 BE patients were evaluated in a random order using a web-based module. All ROIs contained histopathology correlations enabled by VLE laser marking. Assessors were blinded to endoscopic BE images and histology. ROIs were first scored as nondysplastic or neoplastic. Level of confidence was assigned to the predicted diagnosis. Outcome measures were: (i) diagnostic performance of VLE assessors for identification of BE neoplasia in all VLE ROIs, defined as accuracy, sensitivity, and specificity; (ii) diagnostic performance of VLE assessors for only high level of confidence predictions; and (iii) interobserver agreement. Accuracy, sensitivity, and specificity for BE neoplasia identification were 79% (confidence interval [CI], 75–83), 75% (CI, 71–79), and 81% (CI, 76–86), respectively. When neoplasia was identified with a high level of confidence, accuracy, sensitivity, and specificity were 88%, 83%, and 90%, respectively. The overall strength of interobserver agreement was fair (k = 0.29). VLE assessors can identify BE neoplasia with reasonable diagnostic accuracy in histopathology-correlated VLE ROIs, and accuracy is enhanced when BE neoplasia is identified with high level of confidence. Future work should focus on renewed VLE image reviewing criteria and real-time automatic assessment of VLE scans.

BACKGROUND: Multiband mucosectomy (MBM) is the preferred technique for piecemeal resection of early neoplastic lesions in Barrett's esophagus (BE). The currently most widely used device for MBM is the Duette device. Recently, the Captivator EMR device has come available which might have practical advantages over the Duette device.METHODS: Phase I was a randomized pre-esophagectomy trial with a non-inferiority design aiming to compare EMR specimens obtained with the Captivator and the Duette device.PRIMARY OUTCOME: max diameter of the EMR specimens, secondary outcomes: min diameter, max thickness of the EMR specimens and resected submucosal stroma. Phase II were clinical pilot cases aiming to evaluate the feasibility of EMR using the Captivator device. Primary outcome was the successful EMR rate and secondary outcomes included procedure time and adverse events.RESULTS: Phase I: 24 EMR specimens (12 pairs) were obtained from six patients. The median max diameter of EMR specimens obtained with the Captivator device was 16 mm [IQR 12-21] versus 18 mm [IQR 13-23] for the Duette device. Non-inferiority of the max diameter of the Captivator specimens could not be demonstrated (median difference 1 mm, 95% CI - 3.26 to + 5.26). However, when using paired analysis, no significant difference was found (p 0.573). In addition, no statistically significant differences were found in the min diameter, max thickness of EMR specimens, and max thickness of resected submucosal stroma. Phase II: 5 BE patients with early neoplastic lesions were included. Successful EMR was achieved in 100%. Median procedure time was 33 min (IQR 25-39). One patient developed transient dysphagia, without signs of stenosis on endoscopy.CONCLUSIONS: EMR of early Barrett's neoplasia using the Captivator device is comparable to Duette EMR when looking at size of resected specimens. In the first patients, EMR using the Captivator was feasible, resulting in successful resection without acute adverse events.

Introduction: The risk of lymph node metastases (LNM) in submucosal esophageal adenocarcinoma (EAC) patients is subject to debate. These patients might be treated endoscopically if the risk of LNM appears to be low.Objective: The objective of this article is to evaluate the outcome of patients who underwent an endoscopic resection (ER) and subsequent endoscopic follow-up for a submucosal EAC.Methods: All patients who underwent ER for submucosal EAC between January 2012 and August 2016 and were subsequently managed with endoscopic follow-up were retrospectively identified. Primary outcome was the number of patients diagnosed with LNM; secondary outcomes included intraluminal recurrences.Results: Thirty-five patients (median age 68 years) were included: 17 low-risk (submucosal invasion 500 microns, and/or G3-G4, and/or LVI, and/or a tumor-positive deep resection margin (R1)) EACs. After a median follow-up of 23 (IQR 15-43) months, in which patients underwent a median of six (IQR 4-8) endoscopies and a median of four (IQR 2-8) endoscopic ultrasound procedures, none of the included patients were diagnosed with LNM. Five (14%) patients developed a local intraluminal recurrence a median of 18 (IQR 11-21) months after baseline ER that were treated endoscopically.Conclusions: In 35 patients with a submucosal EAC, no LNM were found during a median follow-up of 23 months. Endoscopic therapy may be an alternative for surgery in selected patients with a submucosal EAC.

Background: Dysplasia in Barrett's esophagus (BE) biopsies is associated with low observer agreement among general pathologists. Therefore, expert review is advised. We are developing a web-based, national expert review panel for histological review of BE biopsies.Objective: The aim of this study was to create benchmark quality criteria for future members.Methods: Five expert BE pathologists, with 10-30 years of BE experience, weekly handling 5-10 cases (25% dysplastic), assessed a case set of 60 digitalized cases, enriched for dysplasia. Each case contained all slides from one endoscopy (non-dysplastic BE (NDBE), n = 21; low-grade dysplasia (LGD), n = 20; high-grade dysplasia (HGD), n = 19). All cases were randomized and assessed twice followed by group discussions to create a consensus diagnosis. Outcome measures: percentage of 'indefinite for dysplasia' (IND) diagnoses, intra-observer agreement, and agreement with the consensus 'gold standard' diagnosis.Results: Mean percentage of IND diagnoses was 8% (3-14%) and mean intra-observer agreement was 0.84 (0.66-1.02). Mean agreement with the consensus diagnosis was 90% (95% prediction interval (PI) 82-98%).Conclusion: Expert pathology review of BE requires the scoring of a limited number of IND cases, consistency of assessment and a high agreement with a consensus gold standard diagnosis. These benchmark quality criteria will be used to assess the performance of other pathologists joining our panel.

Management of Barrett's esophagus (BE) relies heavily on histopathological assessment of biopsies, associated with significant intra- and interobserver variability. Guidelines recommend biopsy review by an expert in case of dysplasia. Conventional review of biopsies, however, is impractical and does not allow for teleconferencing or annotations. An expert digital review platform might overcome these limitations. We compared diagnostic agreement of digital and conventional microscopy for diagnosing BE +/- dysplasia. Sixty BE biopsy glass slides (non-dysplastic BE (NDBE); n = 25, low-grade dysplasia (LGD); n = 20; high-grade dysplasia (HGD); n = 15) were scanned at x20 magnification. The slides were assessed four times by five expert BE pathologists, all practicing histopathologists (range: 5-30 years), in 2 alternating rounds of digital and conventional microscopy, each in randomized order and sequence of slides. Intraobserver and pairwise interobserver agreement were calculated, using custom weighted Cohen's kappa, adjusted for the maximum possible kappa scores. Split into three categories (NDBE, IND, LGD+HGD), the mean intraobserver agreement was 0.75 and 0.84 for digital and conventional assessment, respectively (p = 0.35). Mean pairwise interobserver agreement was 0.80 for digital and 0.85 for conventional microscopy (p = 0.17). In 47/60 (78%) of digital microscopy reviews a majority vote of >= 3 pathologists was reached before consensus meeting. After group discussion, a majority vote was achieved in all cases (60/60). Diagnostic agreement of digital microscopy is comparable to that of conventional microscopy. These outcomes justify the use of digital slides in a nationwide, web-based BE revision platform in the Netherlands. This will overcome the practical issues associated with conventional histologic review by multiple pathologists

Little evidence is available about survival rates in patients with recurrent disease after potentially curative surgery for esophageal or junctional cancer. Only in limited occasions, potentially curative salvage strategies are available. The aim of this study is to analyze survival rates and patterns of dissemination, and to identify independent prognostic factors in a consecutive series of patients who develop recurrent esophageal or junctional cancer. Between 1994 and 2015, patients who developed disease recurrence after neoadjuvant chemo(radio) therapy followed by radical esophagectomy for esophageal or junctional cancer were retrospectively analyzed. The Kaplan-Meier estimates were performed to calculate and compare overall survival between patients with different patterns of dissemination and to compare between different treatment strategies. Furthermore, univariate and multivariate Cox-regression analyses were performed to identify independent prognostic factors for post recurrence survival. In this study, we included 219 patients. The median overall survival of all included patients was 3.2 months (range: 0.0-101.1 months). The median overall survival in patients with exclusively locoregional recurrence (n = 23, 10.8%) was 4.9 months (range: 0.1-55.6) and 2.9 months (range: 0.0-101.1) in patients who had distant metastases (n = 189, 89.2%), P = 0.003. Patients who received treatment aimed at complete tumor eradication (n = 28, 13.7%) had a median overall survival of 13.6 months (range: 1.1-101.1) and palliative treated patients (n = 94, 46.1%) of 4.7 months (range: 0.3-25.6), P

Research Data for Adherence to pre-set benchmark quality criteria to qualify as expert assessor of dysplasia in Barrett’s esophagus biopsies – towards digital review of Barrett’s esophagus by MJ van der Wel, E Klaver, LC Duits, RE Pouw, CA Seldenrijk, GJA Offerhaus, M Visser, FJW ten Kate, K Biermann, LAA Brosens, M Doukas, C Huysentruyt, A Karrenbeld, G Kats-Ugurlu, JS van der Laan, G van Lijnschoten, FCP Moll, AHAG Ooms, JG Tijssen, JJGHM Bergman and SL Meijer in United European Gastroenterology Journal

Background: Dysplasia assessment of Barrett's esophagus biopsies is associated with low observer agreement; guidelines advise expert review. We have developed a web-based review panel for dysplastic Barrett's esophagus biopsies.Objective: The purpose of this study was to test if 10 gastrointestinal pathologists working at Dutch Barrett's esophagus expert centres met pre-set benchmark scores for quality criteria.Methods: Ten gastrointestinal pathologists twice assessed 60 digitalized Barrett's esophagus cases, enriched for dysplasia; then randomised (7520 assessments). We tested predefined benchmark quality criteria: (a) percentage of 'indefinite for dysplasia' diagnoses, benchmark score ≤14% for all cases, ≤16% for dysplastic subset, (b) intra-observer agreement; benchmark score ≥0.66/≥0.39, (c) percentage agreement with 'gold standard diagnosis'; benchmark score ≥82%/≥73%, (d) proportion of cases with high-grade dysplasia underdiagnosed as non-dysplastic Barrett's esophagus; benchmark score ≤1/78 (≤1.28%) assessments for dysplastic subset.Results: Gastrointestinal pathologists had seven years' Barrett's esophagus-experience, handling seven Barrett's esophagus-cases weekly. Three met stringent benchmark scores; all cases and dysplastic subset, three met extended benchmark scores. Four pathologists lacked one quality criterion to meet benchmark scores.Conclusion: Predefined benchmark scores for expert assessment of Barrett's esophagus dysplasia biopsies are stringent and met by some gastrointestinal pathologists. The majority of assessors however, only showed limited deviation from benchmark scores. We expect further training with group discussions will lead to adherence of all participating gastrointestinal pathologists to quality criteria, and therefore eligible to join the review panel.

Supplemental Material for Adherence to pre-set benchmark quality criteria to qualify as expert assessor of dysplasia in Barrett’s esophagus biopsies – towards digital review of Barrett’s esophagus by MJ van der Wel, E Klaver, LC Duits, RE Pouw, CA Seldenrijk, GJA Offerhaus, M Visser, FJW ten Kate, K Biermann, LAA Brosens, M Doukas, C Huysentruyt, A Karrenbeld, G Kats-Ugurlu, JS van der Laan, G van Lijnschoten, FCP Moll, AHAG Ooms, JG Tijssen, JJGHM Bergman and SL Meijer in United European Gastroenterology Journal

Esophagectomy for submucosal (T1b) esophageal adenocarcinoma (EAC) is performed in order to optimize patient outcomes given the risk of concurrent lymph node metastases (LNM). However, not seldom, comorbidity precludes these patients from surgery. Therefore, the aim of our study was to assess the course of follow-up after treatment in submucosal EAC patients undergoing surgery versus conservative therapy and to evaluate the incidence of metastatic disease. Between 2001 and 2012, all patients undergoing diagnostic endoscopic resection for EAC in two centers were reviewed. Only patients with histopathologically proven submucosal tumor invasion were included. Submucosal EACs were divided into tumors that were removed radically (R0) and irradically (R1). Subsequently, in the R0 group, EACs were classified as either low risk (LR; submucosal invasion 500 nm, G3-G4 and/or LVI). Metastatic disease was defined as LNM in surgical resection specimen and/or evidence of malignant disease during follow-up (FU). Sixty-nine patients with a submucosal EAC were included [23 R1-resections and 46 R0-resection (14 R0-LR and 32 R0-HR)]. Twenty-six patients underwent surgical treatment (1 R0-LR, 12 R0-HR and 13 R1). None of the 14 R0-LR patients developed metastatic disease after a median FU of 60 months. In the R0-HR group and R1 group, metastatic disease was diagnosed in 16 and 30 % of patients, respectively. Surgical patients tended to have a better overall survival than non-surgical patients (p = 0.09). Tumor-related deaths, however, were 12 % in both groups. In LR submucosal EAC, the risk of metastatic disease appears to be very low. In deep submucosal EAC (either R0- or R1-resection), the rate of metastatic disease is lower than reported in earlier surgical series. Given the reasonable disease-free survival and high background mortality, conservative management of these patients seems to be a valid alternative for surgery in selected cases

In the past decade there have been technological advances in Endoscopic Eradication Therapy (EET) for the management of patients with oesophageal neoplasia and early cancer. Multiple endoscopic techniques now exist for both squamous and Barrett's oesophagus associated neoplasia or early cancer. A fundamental aspect of endotherapy is removal of the target lesion by endoscopic mucosal resection, or endosopic submucosal dissection. Residual tissue is subsequently ablated to remove the risk of recurrence. The most validated technique for Barrett's oesophagus is radiofrequency ablation, but other techniques such as hybrid-APC and cryotherapy also show good results. This chapter will discuss the evolution of EET, and which patients are most likely to benefit. It will also explore the evidence behind the success of different techniques and provide practical advice on how to carry out the endoscopic techniques with a focus on radiofrequency ablation and endoscopic mucosal resection in particular.

Supplemental material, Supplementary Table 2 for Development of benchmark quality criteria for assessing whole-endoscopy Barrett's esophagus biopsy cases by MJ van der Wel, LC Duits, E Klaver, RE Pouw, CA Seldenrijk, GJA Offerhaus, M Visser, FJW ten Kate, JG Tijssen, JJGHM Bergman and SL Meijer in United European Gastroenterology Journal

In a prior study, baseline mutational load (ML) predicted progression to high-grade dysplasia (HGD) or esophageal adenocarcinoma (EAC) in Barrett's esophagus (BE) with an area under the curve (AUC) of 0.95. We aimed to validate the test characteristics of this predictive biomarker panel using crude DNA lysates in a larger well-characterized cohort. We performed a nested case-control study of BE patients from three tertiary referral centers in the Netherlands. Cases had baseline nondysplastic BE (NDBE) and developed HGD/EAC ≥ 2 years later. Controls were matched 2:1, had baseline NDBE, and no progression. Polymerase chain reaction (PCR)-based mutational analysis was performed on crude lysates from formalin-fixed, paraffin-embedded tissue. ML was calculated from loss of heterozygosity (LOH) and microsatellite instability (MSI) at 10 genomic loci. Receiver operator characteristic (ROC) curves were created to assess the diagnostic utility of various cutoffs of ML for progression. Of 159 subjects, 58 were progressors and 101 were nonprogressors, there was no difference in mean ML in preprogression tissue in progressors and nonprogressors (ML = 0.73 ± 0.69 vs. ML = 0.74 ± 0.61, P = 0.93). ROC curves showed poor discrimination of ML in predicting progression with AUC of 0.50 at ML ≥ 1. AUC did not vary with different ML cut-points. The utility of the ML to stratify BE patients for risk of progression was not confirmed in this study. The etiology for discrepancies between this and prior studies showing high predictiveness is likely due to the use of crude lysates in this study, but requires further investigation.

Supplemental material, Supplementary Table 1 for Development of benchmark quality criteria for assessing whole-endoscopy Barrett's esophagus biopsy cases by MJ van der Wel, LC Duits, E Klaver, RE Pouw, CA Seldenrijk, GJA Offerhaus, M Visser, FJW ten Kate, JG Tijssen, JJGHM Bergman and SL Meijer in United European Gastroenterology Journal

In the treatment of early esophageal Barrett's neoplasia, radiofrequency ablation may be hindered by stenosis due to prior endoscopic resection (ER). The flexible balloon-based circumferential CryoBalloon Ablation System (CBAS) may overcome this problem by the conformability of the compliant balloon which might enable circumferential cryoablation in a stenosis. The aim of the current study was to evaluate the feasibility of the CBAS as well as the dose-response effect of cryoablation in a strictured esophagus model. In six pigs, a stenosis was induced by ER (3 cm in length, 75% of circumference) in the proximal, mid, and distal esophagus. After 28 days, cryoablation with the CBAS was performed, with the length of ablation time (6, 8, or 10 seconds) randomly assigned per stricture location within the esophagus. Four days post-ablation, the esophagi were harvested for histopathological assessment of the percentage of the total circumference affected by cryoablation and the maximum depth of necrosis. At 28 days, all 18 ER areas had transformed into strictures with ±50% of its original diameter remaining. In 9 of 18 strictures, more than one attempt for cryoablation was necessary due to displacement of the balloon. Histopathological evaluation showed a wide range in circumferential uniformity (0-100%) and maximum necrosis depth (epithelium to external proper muscle layer) of cryoablation, both independent of ablation times. Deepest ablation effects were seen at the center of the resection-induced scar. This first generation CryoBalloon Focal Ablation System was not feasible for ablation within severe stenoses, since it results in inconsistent circumferential uniformity of cryoablation with subsequent differences in depth of ablation. Further research with a next generation CBAS in a more realistic stricture model is warranted.

Summary High-risk early esophageal adenocarcinoma (i.e. submucosal invasion >500 nm, poor differentiation, and/or presence of lymphovascular invasion) is currently treated with esophagectomy with lymph node (LN) dissection given the high rates of LN metastases. However, esophagectomy is associated with substantial morbidity and mortality. Endoscopic radical resection followed by thoracolaparoscopic LN dissection without concomitant esophagectomy could be an alternative. The study aim was to evaluate the feasibility and safety of thoracolaparoscopic dissection of esophageal LNs in a preclinical setting. (i) In human cadavers, thoracolaparoscopic dissection of LNs involved in drainage of the esophagus was performed. Subsequently, esophagectomy was performed to be able to detect retained LNs. Outcome parameters included the number of dissected LNs, the number of retained LNs in the esophagectomy specimen (ES), and technical success. (ii) In swine, thoracolaparoscopic LN dissection was also performed. After the procedure, the swine survived for 28 days. Thereafter, the swine were sacrificed and esophagectomy was performed. Outcome parameters included the presence of ischemia and/or stenosis in the ES and other complications. (i) In five human cadavers, a median of 26 LNs (interquartile range 22–46) were dissected. In two ES, one retained LN was found: one high paraesophageal, one low paraesophageal. Technical success rate was 100%. (ii) None of the seven porcine ES showed signs of ischemia or stenosis. One swine died because of ventricular fibrillation during surgery; during follow up no complications were observed. Thoracolaparoscopic dissection of LNs involved in the drainage of the esophagus is feasible in human cadavers and swine. The porcine survival study suggests that the esophageal vascularity is not severely compromised by the procedure. As anatomy differs between swine and humans, safety of the procedure will have to be investigated thoroughly before applying this new technique as the treatment of choice.

Volumetric laser endomicroscopy (VLE) is a novel balloon-based optical coherence tomography (OCT) imaging technique that may improve detection of early neoplasia in Barrett's esophagus (BE). Most OCT studies lack a direct correlation between histology and OCT images. The aim is to investigate the optimal approach for achieving one-to-one correlation of ex-vivo VLE images of endoscopic resection (ER) specimens with histology. BE patients with and without early neoplasia underwent ER after delineating areas with electrocoagulation markers (ECM). After ER, specimens underwent additional ex-vivo marking with several different markers (ink, pin, Gold Probe) followed by ex-vivo VLE scanning. ER specimens were carefully sectioned into tissue blocks guided by the markers. Histology and VLE slides were considered a match if ≥ 2 markers were visible on both modalities and mucosal patterns aside from these markers matched on both histology and VLE. From 16 ER specimens 120 tissue blocks were sectioned of which 23 contained multiple markers. Fourteen histology-VLE matches were identified. ECMs and ink markers proved to be the most effective combination for matching. The last 6/16 ER specimens yielded 9/14 matches, demonstrating a learning curve due to methodological improvements in marker placement and tissue block sectioning. One-to-one correlation of VLE and histology is complex but feasible. The groundwork laid in this study will provide high-quality histology-VLE correlations that will allow further research on VLE features of early neoplasia in BE.

High-risk submucosal esophageal adenocarcinoma's might be treated curatively by means of radical endoscopic resection, followed by thoracolaparoscopic lymphadenectomy without concomitant esophagectomy. A preclinical study has shown the feasibility and safety of this approach; however, no studies are performed in a clinical setting. In addition, sentinel node navigation surgery could be valuable in tailoring the extent of the lymphadenectomy. This study aimed to evaluate the feasibility and safety of thoracolaparoscopic lymphadenectomy without esophagectomy (phase I) and sentinel node navigation surgery (phase II) in patients with early esophageal adenocarcinoma. Patients with T1N0M0 early esophageal adenocarcinoma scheduled for esophagectomy without neoadjuvant therapy were included. Phase I: Two-field, esophagus preserving, thoracolaparoscopic lymphadenectomy was performed, followed by esophagectomy in the same session. Primary outcome parameters were the number of lymph nodes resected, and number of retained lymph nodes in the esophagectomy specimen. Phase II: A radioactive tracer was injected endoscopically the day before surgery. Static imaging was performed 15 and 120 minutes after injection. The day of surgery, sentinel node navigation surgery followed by esophagectomy was performed. Primary outcome parameters were the percentage of patients with a detectable sentinel node, and the concordance between static imaging and probe-based detection of sentinel node. Phase I: Five patients were included, and a median of 30 (IQR: 25-46) lymph nodes was resected. A median of 6 (IQR: 2-9) retained lymph nodes was found in the esophagectomy specimen. No acute adverse events occurred, but near the end of lymphadenectomy esophageal discoloration was observed, possibly indicating ischemia. Phase II: In all five included patients sentinel nodes could be visualized and resected, at a median of 3 (IQR: 2-5) locations. There was a high concordance between imaging and probe-based detection of sentinel nodes. In conclusion, sentinel node navigation surgery followed by lymphadenectomy without concomitant esophagectomy seems feasible in patients with high-risk submucosal early esophageal adenocarcinoma. More evidence is however needed before applying this technique in clinical practice.

Summary Preliminary data show higher stricture rates after radiofrequency ablation (RFA) for early esophageal squamous neoplasia compared with Barrett's esophagus. We studied the effects of Lugol stain (LS) directly prior to RFA on stricture formation in squamous epithelium. Of 16 pigs, the distal half of the esophagus was LS, followed by circumferential RFA (single application 12 J/cm2) in the unstained and stained esophagus. Pigs were euthanized at day 0 (n = 4), 3 (n = 4), or 28 (n = 8). Histology was evaluated in four areas: blank-control (no RFA, no LS), blank-RFA (no LS), LS+RFA, and LS-control (no RFA). Stenosis severity in LS+RFA and blank-RFA at 28 days was assessed by the ratio of the mucosal diameter at the RFA area to the diameter 2 cm proximal of this zone. Histology showed submucosal edema in 50% of LS+RFA versus 0% in blank-RFA. Severity and depth of inflammation (day 3) was equal in LS+RFA and blank-RFA. Severity and depth of fibrosis (day 28) appeared more severe in LS+RFA. Consequently, stenosis was present in 100% (LS+RFA) versus 12.5% (blank-RFA). The stenosis-severity ratio was 0.40 (interquartile range 0.29–0.45) in LS+RFA versus 0.73 (interquartile range 0.64–0.78) in blank-RFA (P = 0.012). Limitations of this study were the difference in uptake of LS between pigs and humans, the difference in esophageal anatomy between pigs and humans, and between the proximal and distal esophagus within pigs. In conclusion, in the porcine squamous esophagus, stenosis rate and severity after RFA increased when preceded by LS. LS may be contributing in the altered response of squamous epithelium to RFA as compared with Barrett's esophagus.

Endoscopic surveillance is recommended for patients with Barrett's esophagus (BE) to detect high-grade intraepithelial neoplasia (HGIN) or early cancer (EC). Early neoplasia is difficult to detect with white light endoscopy and random biopsies are associated with sampling error. Fluorescence spectroscopy has been studied to distinguish non-dysplastic Barrett's epithelium (NDBE) from early neoplasia. The Optical Biopsy System (OBS) uses an optical fiber integrated in a regular biopsy forceps. This allows real-time spectroscopy and ensures spot-on correlation between the spectral signature and corresponding physical biopsy. The OBS may provide an easy-to-use endoscopic tool during BE surveillance. We aimed to develop a tissue-differentiating algorithm and correlate the discriminating properties of the OBS with the constructed algorithm to the endoscopist's assessment of the Barrett's esophagus. In BE patients undergoing endoscopy, areas suspicious for neoplasia and endoscopically non-suspicious areas were investigated with the OBS, followed by a correlating physical biopsy with the optical biopsy forceps. Spectra were correlated to histology and an algorithm was constructed to discriminate between HGIN/EC and NDBE using smoothed linear dicriminant analysis. The constructed classifier was internally cross-validated and correlated to the endoscopist's assessment of the BE segment. A total of 47 patients were included (39 males, age 66 years): 35 BE patients were referred with early neoplasia and 12 patients with NDBE. A total of 245 areas were investigated with following histology: 43 HGIN/EC, 66 low-grade intraepithelial neoplasia, 108 NDBE, 28 gastric or squamous mucosa. Areas with low-grade intraepithelial neoplasia and gastric/squamous mucosa were excluded. The area under the receiver operating characteristic curve of the constructed classifier was 0.78. Sensitivity and specificity for the discrimination between NDBE and HGIN/EC of OBS alone were 81% and 58% respectively. When OBS was combined with the endoscopist's assesssment, sensitivity was 91% and specificity 50%. If this protocol would have guided the decision to obtain biopsies, half of the biopsies would have been avoided, yet 4/43 areas containing HGIN/EC (9%) would have been inadvertently classified as unsuspicious. In this study, the OBS was used to construct an algorithm to discriminate neoplastic from non-neoplastic BE. Moreover, the feasibility of OBS with the constructed algorithm as an adjunctive tool to the endoscopist's assessment during endoscopic BE surveillance was demonstrated. These results should be validated in future studies. In addition, other probe-based spectroscopy techniques may be integrated in this optical biopsy forceps system.

Radiofrequency ablation (RFA) is safe and effective for eradication of Barrett’s esophagus after endoscopic resection (ER) of neoplasia. Widespread ER, however, is likely to induce stenosis, hampering subsequent circumferential RFA. A ‘single step’ procedure with ER and circumferential RFA in the same session may avoid this problem. Two variants are possible: circumferential RFA of Barrett’s esophagus including the lesion followed by ER of the ablated lesion (‘RFA→ER’), or ER of the lesion directly followed by circumferential RFA of remaining Barrett’s esophagus including the resection wound (‘ER→RFA’). First aim was to evaluate perforation risk of ‘ER→RFA’ using increasing RFA energies. Second aim was to compare stenosis rate after ‘ER→RFA’ versus ‘RFA→ER’. In Experiment 1, 24 areas in six pigs underwent widespread ER directly followed by circumferential RFA with increasing energies (2 x 10, 2 x 12-6 x 12 J/cm(2)) in the esophagus. In Experiment 2, eight pigs each had four treatment areas randomized: ‘ER→RFA’, RFA alone, ER alone, and ‘RFA→ER’. No acute perforations occurred when ablating ER wounds. Two delayed perforations occurred: one in experiment 1, another in experiment n2 at the ‘ER→RFA’ area. The remaining seven pigs in experiment 2 showed stenosis in all ‘ER→RFA’ and ‘RFA→ER’ areas versus 5/7 RFA alone areas, and 0/7 ER alone areas. In conclusion, the ‘single step’ variant ‘ER→RFA’ is not safe in this porcine model and seems therefore not ethical to evaluate in humans at this stage. Given the high rate of stenosis after ‘RFA→ER’ and RFA alone, one might question the validity of the porcine model for this type of experiments.

In Barrett's esophagus (BE), second-generation autofluorescence imaging (AFI-II) improves targeted detection of high-grade intra-epithelial neoplasia (HGIN) and early cancer (EC), yet suffers from high false-positive (FP) rates. The newest generation AFI (AFI-III) specifically targets fluorescence in malignant cells and may therefore improve detection of early neoplasia and reduce FP rate. The aim was to compare AFI-III with AFI-II for endoscopic detection of early neoplasia in BE. BE patients with endoscopically inconspicuous neoplasia underwent two diagnostic endoscopies (AFI-II/AFI-III) in a single session. End-points: number of patients and lesions with HGIN/EC detected with AFI-II and AFI-III after white-light endoscopy (WLE) and the value of reinspection of AFI-positive areas with WLE and narrow-band imaging. Forty-five patients were included (38 males, age 65 years). Nineteen patients showed HGIN/EC. AFI-II inspection after WLE increased detection of HGIN/EC from 9 to 15 patients (47 to 79%); AFI-III increased detection from 9 to 17 patients (47 to 89%). WLE plus random biopsies diagnosed 13/19 (68%) HGIN/EC patients. One hundred and four abnormal AFI areas were inspected; 23 (22%) showed HGIN/EC. AFI-II increased detection of HGIN/EC from 10 to 18 lesions (43 to 78%). AFI-III increased detection from 10 to 20 lesions (43-87%). FP rate was 86% for AFI-II and AFI-III. Reinspection with WLE or narrow-band imaging reduced FP rate to 21% and 22%, respectively, but misclassified HGIN/EC lesions as unsuspicious in 54% and 31%, respectively. This first feasibility study on third-generation AFI again showed improved targeted detection of HGIN/EC in BE. However, the results do not suggest AFI-III performs significantly better than conventional AFI-II.

Background and study aims: Radiofrequency ablation (RFA) is safe and effective for the eradication of neoplastic Barrett's esophagus; however, occasionally there is minimal regression after initial circumferential balloon-based RFA (c-RFA). This study aimed to identify predictive factors for a poor response 3 months after c-RFA, and to relate the percentage regression at 3 months to the final treatment outcome. Methods: We included consecutive patients from 14 centers who underwent c-RFA for high grade dysplasia at worst. Patient and treatment characteristics were registered prospectively. "Poor initial responseo" was defined as < 50 % regression of the Barrett's esophagus 3 months after c-RFA, graded by two expert endoscopists using endoscopic images. Predictors of initial response were identified through logistic regression analysis. Results: There were 278 patients included (median Barrett's segment C4M6). In poor initial responders (n = 36; 13 %), complete response for neoplasia (CR-neoplasia) was ultimately achieved in 86 % (vs. 98 % in good responders; P < 0.01) and complete response for intestinal metaplasia (CR-IM) in 66 % (vs. 95 %; P < 0.01). Poor responders required 13 months treatment (vs. 7 months; P < 0.01) for a median of four RFA sessions (vs. three; P < 0.01). We identified four independent baseline predictors of poor response: active reflux esophagitis (odds ratio [OR] 37.4; 95 % confidence interval [CI] 3.2 - 433.2); endoscopic resection scar regeneration with Barrett's epithelium (OR 4.7; 95 %CI 1.1 - 20.0); esophageal narrowing pre-RFA (OR 3.9; 95 %CI 1.0 - 15.1); and years of neoplasia pre-RFA (OR 1.2; 95 %CI 1.0 - 1.4). Conclusions: Patients with a poor initial response to c-RFA have a lower ultimate success rate for CR-neoplasia/CR-IM, require more treatment sessions, and a longer treatment period. A poor initial response to c-RFA occurs more frequently in patients who regenerate their endoscopic resection scar with Barrett's epithelium, and those with ongoing reflux esophagitis, neoplasia in Barrett's esophagus for a longer time, or a narrow esophagus.

Background and study aims: Endoscopic resection for esophageal squamous high-grade intraepithelial neoplasia (HGIN) or intramucosal cancer (esophageal squamous cell carcinoma [ESCC]) with the endoscopic resection cap technique is technically difficult, and requires submucosal lifting and multiple snares for piecemeal resections. Multiband mucosectomy (MBM) is an easy-to-use endoscopic resection technique and may be the modality of choice in China, where ESCC is extremely prevalent. The aim of the current study was to prospectively evaluate MBM for piecemeal endoscopic resection of squamous neoplasia of the esophagus. Methods: Patients with HGIN/ESCC and no signs of submucosal invasion or metastatic disease were included in the study. Lesions were delineated using electrocoagulation and resected using the MBM technique. Endpoints were procedure time, endoscopic radicality, complications, histology of the endoscopic resection specimens, and absence of HGIN/ESCC at the endoscopic resection scar during follow-up. Results: A total of 41 patients (26 male; mean age 61 years) underwent MBM; all lesions were visible with white light endoscopy (median length 5 cm, interquartile range [IQR] 4 – 6 cm; median circumferential extent 42 %, IQR 25 – 50 %). Median procedure time was 12 minutes (IQR 8 – 24 minutes). Median number of resections was 5 (IQR 3 – 6). Endoscopic complete resection was achieved in all lesions. There was one perforation, which was treated by application of clips. No other complications were observed. The worst histology was ESCC (n = 19), HGIN (n = 17), middle grade intraepithelial neoplasia (n = 4), and normal squamous epithelium (n = 1). Endoscopic follow-up at 3 months showed HGIN at the endoscopic resection scar in two patients, which was effectively treated endoscopically, and showed normal squamous epithelium in all patients at final follow-up (median 15 months, IQR 12 – 24 months). Conclusion: This first prospective study on MBM for piecemeal endoscopic resection of early esophageal squamous neoplasia showed that MBM was effective for the complete removal of lesions with short procedure time, few complications, effective histological assessment of resected specimens, and durable treatment effect.

Esophagectomy in elderly esophageal carcinoma patients is correlated with a high morbidity and even mortality. Studies on neoadjuvant chemoradiotherapy (NT) in elderly patients are scarce. The aim of this study was to evaluate the effect of advanced age in combination with NT in esophageal carcinoma patients who underwent an esophagectomy. Patients who underwent NT prior to esophagectomy between 1993 and 2010 were divided into three groups

Background: Chemoradiotherapy is increasingly applied in patients with oesophageal cancer. The aim of the present study was to determine whether 3D-CT volumetry is able to differentiate between responding and non-responding oesophageal tumours early in the course of neoadjuvant chemoradiotherapy. Patients and methods: Serial CT before and after two weeks of neoadjuvant chemoradiotherapy was performed in the multimodality treatment arm of a randomised trial including patients with oesophageal carcinoma. CT response was measured with the change in tumour volume between baseline and after 14 days of neoadjuvant therapy. Receiver Operating Characteristic (ROC) analysis was used to evaluate the ability of 3D-CT as an early imaging marker of response. Results: CT response analysis was performed in 39 patients, of whom 26 patients were histopathological responders. Median tumour volume increased between baseline and after 14 days of chemoradiotherapy in histopathological responders as well as in non-responders, though changes were not statistically significant. The area under the ROC curve was 0.71. Conclusion: Tumour volume changes after 14 days of neoadjuvant chemoradiotherapy as measured by 3D-CT were not associated with histopathological tumour response. CT volumetry should not be used for early response assessment in patients with potentially curable oesophageal cancer treated with neoadjuvant chemoradiotherapy. (C) 2011 Elsevier Ltd. All rights reserved.

Background and study aims: Endoscopic treatment of early neoplasia in Barrett's esophagus preserves the esophagus and is minimally invasive compared with surgical treatment. However, the influence of endoscopic therapy on quality of life (QOL) and fear of cancer recurrence is unknown. We explored QOL and fear of cancer recurrence 12-60 months after endoscopic and surgical treatment for early Barrett's neoplasia, using a cross-sectional design. Patients and methods: A total of 81 patients with early Barrett's neoplasia underwent endoscopic treatment and 33 patients underwent surgery. The choice of treatment was based on tumor size, depth of penetration or patient preference. QOL was measured using the SF-36, EORTC-QLQ-C30, and the EORTC-QLQ-OES18 questionnaires. Anxiety and fear of recurrence were measured using the Hospital Anxiety and Depression Scale (HADS) and the Worry Of Cancer Scale (WOCS). Results: In total, 66 endoscopy patients and 29 surgery patients were eligible for the study. Questionnaires were completed by 64/66 (97%) endoscopy patients and 27/29 (93%) surgery patients. Multivariate analyses were conducted, with sex, age, comorbidity, and histology of the resected specimen used as covariates. Patients in the surgery group reported significantly more eating problems (OR = 18.3; P

Udgivelsesdato: 2009-Jan BACKGROUND AND AIM: Stepwise endoscopic circumferential and focal radiofrequency ablation is safe and effective for the eradication of Barrett's esophagus. In contrast to other techniques, radiofrequency ablation appears to avoid significant esophageal scarring or stenosis. Our aim was to evaluate whether radiofrequency ablation has an adverse effect on esophageal function in patients treated for Barrett's esophagus containing intramucosal cancer and/or high-grade dysplasia. METHODS: Twelve patients with Barrett's esophagus containing intramucosal cancer or high-grade dysplasia were included in the study. After endoscopic resection of visible abnormalities, stepwise circumferential and focal ablation were performed every 2 months up to a maximum of five sessions. Measurement of the inner diameter was performed at 1-cm intervals in the distal esophagus. Manometry was performed using a water-perfused sleeve catheter. Compliance was evaluated using the functional lumen imaging probe (FLIP), measuring eight cross-sectional areas within a saline-filled bag with two pressure side holes, one proximal to and one inside the bag. Esophageal sizing, manometry, and compliance were recorded in patients at baseline and at least 2 months after the final ablation session. In addition, FLIP and manometry measurements were performed in 10 healthy volunteers. RESULTS: All patients achieved complete eradication of dysplasia and Barrett's esophagus, without severe complications or ablation-related stenoses. The esophageal diameter was unchanged by the ablation. Lower esophageal sphincter pressure and length and esophageal contraction amplitude before and after ablation were not significantly different. Baseline compliance was significantly different between healthy volunteers and Barrett's esophagus patients. Compliance was not, however, significantly changed by ablation. CONCLUSIONS: Stepwise circumferential and focal ablation of Barrett's esophagus is an effective and safe treatment modality for early Barrett's neoplasia that appears to preserve the functional characteristics of the esophagus.

Background and study aims We have recently proposed a classification of mucosal morphology in Barrett's esophagus based on three criteria: regularity of mucosal pattern, regularity of vascular pattern, and presence of abnormal blood vessels. We aimed to evaluate the interobserver agreement with the proposed mucosal morphology classification and to assess the additional value of narrow band imaging (NBI) over high resolution white light endoscopy (HR-WLE). Patients and methods Five international experts in the field of Barrett's imaging and seven community endoscopists with no expertise in this field independently evaluated magnified still images from 50 areas, obtained with HR-WLE and NBI, in Barrett's esophagus patients. Visual analogue scales (VAS) were used for scoring imaging quality. Interobserver agreement for mucosal morphology and yield for identifying early neoplasia were assessed. Results Imaging qualities of NBI were rated more highly than HR-WLE, when evaluated separately as well as in a side-by-side comparison. The interobserver agreement ranged from 0.40 to 0.56 and did not significantly differ between expert and non-expert endoscopists. The overall yield for correctly identifying images of early neoplasia was 81 % for HR-WLE, 72 % for NBI and 83 % for HR-WLE + NBI, with no significant difference between experts and non-experts. Conclusion Interobserver agreement for the classification of mucosal morphology was moderate. Although NBI was rated more highly than HR-WLE for imaging quality, this did not result in improved interobserver agreement or increased yield for identifying early neoplasia in Barrett's esophagus. This applied to non-expert as well as expert endoscopists.

Background and study aims: Stepwise circumferential and focal ablation of nondysplastic Barrett's esophagus has proven safe and effective. This study assessed the efficacy and safety of ablation for Barrett's esophagus with high-grade dysplasia (HGD), and residual Barrett's esophagus with dysplasia after prior endoscopic resection for visible lesions. Patients and methods: This was a prospective cohort study. All visible abnormalities were resected prior to ablation. Persistence of dysplasia and absence of invasive cancer was confirmed with biopsies after endoscopic resection. A balloon-based electrode was used for primary circumferential ablation and an endoscope-mounted electrode was used for secondary focal ablation. Eradication of dysplasia and Barrett's esophagus was the main outcome measure. Results: Eleven patients (eight men; median age 60 years) were treated (median Barrett's length 5 cm). Visible abnormalities were removed with endoscopic resection in six patients. The worst pathological grade of residual Barrett's esophagus after endoscopic resection and prior to ablation was LGD (n=2) and HGD (n=9). Patients underwent a median of two circumferential and two focal ablation sessions. Complete remission of dysplasia and complete endoscopic and histological removal of Barrett's esophagus was achieved in 11/11 patients (100%). There were no adverse events or strictures, and in none of the 473 biopsies of neo-squamous mucosa was subsquamous Barrett's esophagus ("buried Barrett's") observed. During a median follow-up period of 14 months after the last treatment session and a median number of two follow-up endoscopies, none of the patients showed recurrence of dysplasia or endoscopic signs of recurrent Barrett's mucosa. Conclusions: Stepwise circumferential and focal ablation appears to be a safe and effective treatment for complete removal of Barrett's esophagus containing HGD, and can be safely performed after prior endoscopic resection for endoscopically visible abnormalities.

In recent years, endoscopic therapy of early Bar− rett’s esophagus neoplasia has become a safe and effective alternative to esophagectomy [1 ± 4]. Only patients with high−grade intraepithelial neoplasia (HGIN) or mucosal cancer are eligible for curative endoscopic treatment. Lesions that invade the submucosa are associated with a sig− nificant risk of lymph node metastases and are therefore preferably to be treated surgically. There are two main types of endoscopic therapy: endoscopic resection and endoscopic ablation. An important difference between these two modalities is that endoscopic resection permits histopathological evaluation of the resection spe− cimen, whereas this safeguard is missing with endoscopic ablation therapy. A practical ap− proach is to resect the areas with endoscopically visible lesions by endoscopic resection followed by ablation of residual Barrett’s esophagus [5± 8]. This assumes that if the histopathological evaluation of the most involved areas is favor− able, the chances that the residual Barrett’s esophagus harbors more advanced neoplasia elsewhere are small and thus additional ablation therapy without histological correlation is justi− fied. It is, therefore, crucial that the most in− volved area in the Barrett’s esophagus is indeed identified and resected rather than overlooked and ablated, since this may lead to undertreat− ment of submucosal lesions. In this review, we will discuss the endoscopic work−up for diagnosis and staging of early neo− plasia in Barrett’s esophagus (i. e., HGIN or muco− sal cancer), including the role of advanced ima− ging techniques and the importance of histopa− thological evaluation by endoscopic resection. Diagnosis ! Endoscopic detection of early neoplasia in Barrett’s esophagus The goal of endoscopic surveillance of patients with Barrett’s esophagus is the detection of early neoplastic lesions. To ensure the detection of ear− ly neoplastic lesions there are three rules that should be followed. These rules relate to the en− doscopic equipment used, the “detecting eye” of the endoscopist, and a systematic, meticulous approach.

Study aims: The aim of the current study was to evaluate the efficacy and safety of stepwise circumferential and focal ablation using the HALO system for Barrett's esophagus containing flat, high-grade dysplasia (HGD) or residual dysplasia after endoscopic resection for HGD or intramucosal cancer (IMC). Methods: Visible abnormalities were removed with endoscopic resection prior to ablation. Persistence of dysplasia and absence of IMC were confirmed with biopsy after endoscopic resection. A balloon-based electrode was used for primary circumferential ablation and an endoscope-mounted electrode was used for secondary focal ablation. Results: Twelve patients (nine men: median age 70 years) were treated (median Barrett's length 7 cm). Visible abnormalities were removed by endoscopic resection in seven patients. The worst pathological grade of residual Barrett's esophagus after resection and prior to ablation was low-grade dysplasia (LGD) (n=1) and HGD (n=11). Patients underwent a median of one circumferential and two focal ablation sessions. Complete remission of dysplasia was achieved in 12/12 patients (100%). Complete endoscopic and histological removal of Barrett's esophagus was achieved in 12/12 patients (100%). There were no ablation-related stenoses, and no subsquamous Barrett's esophagus was observed in 363 biopsies obtained from post-ablation neo-squamous mucosa. Protocolized cleaning of the ablation zone and electrode in between ablations resulted in superior regression of Barrett's esophagus compared with previous studies. During a median follow-up of 14 months no recurrence of dysplasia or Barrett's esophagus was observed. Conclusions: Stepwise circumferential and focal ablation for Barrett's esophagus with flat HGD or for Barrett's with residual dysplasia after endoscopic resection for HGD/IMC is a safe and effective treatment modality. Its success rate and safety profile compare favorably with alternatives such as esophagectomy, widespread endoscopic resection or photodynamic therapy.

Evaluation of patients with Barrett's oesophagus (BO) using dye-based chromoendoscopy, optical chromoendoscopy, autofluorescence imaging, or confocal laser endomicroscopy does not significantly increase the number of patients with a diagnosis of early neoplasia compared with high-definition white light endoscopy (HD-WLE) with random biopsy analysis. These newer imaging techniques are not more effective in standard surveillance of patients with BO because the prevalence of early neoplasia is low and HD-WLE with random biopsy analysis detects most cases of neoplasia. The evaluation and treatment of patients with BO and early-stage neoplasia should be centralized in tertiary referral centers, where procedures are performed under optimal conditions, by expert endoscopists. Lesions that require resection are almost always detected by HD-WLE, although advanced imaging techniques can detect additional flat lesions. However, these are of limited clinical significance because they are effectively eradicated by ablation therapy. No endoscopic imaging technique can reliably assess submucosal or lymphangio-invasion. Endoscopic resection of early-stage neoplasia in patients with BO is important for staging and management. Optical chromoendoscopy can also be used to evaluate lesions before endoscopic resection and in follow-up after successful ablation therapy.

The new Cryoballoon Focal Ablation System (CbFAS), a through-the-scope catheter with battery-powered handle that delivers cryogenic fluid into an inflated balloon, differs from current cryotherapy methods used for treatment of Barrett's epithelium. In this dose-finding study, short- and long-term histopathological effects and safety of the CbFAS were evaluated. Cryoablations with (supra)therapeutic durations (4-24 seconds) were performed in pigs that survived for 12 or 48 hours or 4 or 28 days. Next, cryoablations (durations based on animal data) were performed in normal mucosa of esophageal cancer patients scheduled to undergo esophagectomy. The outcome parameters, the occurrence of any bleeding or perforation, the histological presence of edema, inflammation, and necrosis throughout the esophageal wall layers, were evaluated. A total of 60 cryoablations were performed in 11 pigs. 48 hour cryoablations with therapeutic durations (4-10 seconds) resulted in edema/inflammation as deep as the serosa and necrosis ranging from submucosa to serosa with a median depth of 3.2 mm. In 4 day cryoablations this was in the serosa, and muscularis tunica to serosa at a median depth of 4.5 mm, respectively. No necrosis or inflammation remained after 28 days, not even after supratherapeutic cryoablation (12-24 seconds). No acute or delayed bleeding or perforation was observed. Next, eight 6-second cryoablations were performed in four patients. Direct postablation mucosal necrosis was observed; after 4 days necrosis and inflammation was limited to the submucosa. CbFAS cryoablation penetrates deeply into the esophageal wall layers resulting in severe early ablation. After 4 weeks, little injury and no fibrosis remain, even after supratherapeutic durations of administration, suggesting that CbFAS combines deep ablation with a potentially favorable safety profile.