Neosquamous epithelium does not typically arise from Barrett's epithelium

Does radiofrequency ablation of the lower oesophagus allow for clonal expansion of highly mutated neosquamous epithelium?

Objective

In Barrett's oesophagus (BE), after radiofrequency ablation (RFA), the oesophagus can be repopulated with a stratified 'neosquamous epithelium' (NeoSE). While histologically normal, the origin and clonal make-up of this NeoSE is unknown. An increased understanding of NeoSE is important as some studies suggest that NeoSE is biologically abnormal. The aim of this study was to determine whether there were major differences in the mutational landscape or clonal size in NeoSE versus normal squamous epithelium and determine whether NeoSE shares any pathogenic mutations with BE.

Methods and analysis

10 patients who underwent RFA and 10 samples from 8 control patients were sequenced using a clinical targeted sequencing platform (cohort 1). An additional, eight patients with paired preablation BE and postablation NeoSE were also sequenced (cohort 2). Patient advocates will be used to disseminate the findings of this study.

Results

NeoSE samples had a mean of 2.2 pathogenic mutations per sample, including 50% of samples with an NOTCH1 and 30% of samples with a TP53 mutation. The normal oesophagus samples had 1.5 mutations per sample, including 40% of samples with NOTCH1 and 10% of samples with TP53 mutations. There was no difference in mutational allele fractions between NeoSE and normal squamous samples. When we compared paired BE and NeoSE samples, no shared mutations were identified.

Conclusion

While there was a trend for more TP53 mutations in NeoSE, overall, the mutational profile and clonal sizes (allele fractions) were very similar, suggesting NeoSE is genomically similar to the normal oesophageal squamous epithelium.

An Endoscopic and Histologic Study on Healing of Radiofrequency Ablation Wounds in Patients With Barrett's Esophagus

INTRODUCTION

Radiofrequency ablation (RFA) of Barrett's esophagus (BE) inflicts a wound spanning 3 epithelial types (stratified squamous, Barrett's metaplasia, gastric epithelium), yet the esophageal injury heals almost completely with squamous epithelium. Knowledge of how this unique wound heals might elucidate mechanisms underlying esophageal metaplasia. We aimed to prospectively and systematically characterize the early endoscopic and histologic features of RFA wound healing.

METHODS

Patients with nondysplastic BE had endoscopy with systematic esophageal photographic mapping, biopsy, and volumetric laser endomicroscopy performed before and at 1, 2, and 4 weeks after RFA.

RESULTS

Seven patients (6 men; mean age 56.1 ± 10.9 years) completed this study. Squamous re-epithelialization of RFA wounds did not only progress exclusively through squamous cells extending from the proximal wound edge but also progressed through islands of squamous epithelium sprouting throughout the ablated segment. Volumetric laser endomicroscopy revealed significant post-RFA increases in subepithelial glandular structures associated with the squamous islands. In 2 patients, biopsies of such islands revealed newly forming squamous epithelium contiguous with immature-appearing squamous cells arising from esophageal submucosal gland ducts. Subsquamous intestinal metaplasia (SSIM) was found in biopsies at 2 and/or 4 weeks after RFA in 6 of 7 patients.

DISCUSSION

RFA wounds in BE are re-epithelialized, not just by squamous cells from the proximal wound margin but by scattered squamous islands in which esophageal submucosal gland duct cells seem to redifferentiate into the squamous progenitors that fuel squamous re-epithelialization. SSIM can be found in most patients during the healing process. We speculate that this SSIM might underlie Barrett's recurrences after apparently successful eradication.

The Role of Cancer Stem Cells in Drug Resistance in Gastroesophageal Junction Adenocarcinoma

Gastroesophageal junction adenocarcinomas (GEJA) have dramatically increased in incidence in the western world since the mid-20^th century. Their prognosis is poor, and conventional anti-cancer therapies do not significantly improve survival outcomes. These tumours are comprised of a heterogenous population of both cancer stem cells (CSC) and non-CSCs, with the former playing a crucial role in tumorigenesis, metastasis and importantly drug resistance. Due to the ability of CSCs to self-replicate indefinitely, their resistance to anti-cancer therapies poses a significant barrier to effective treatment of GEJA. Ongoing drug development programmes aim to target and eradicate CSCs, however their characterisation and thus identification is difficult. CSC regulation is complex, involving an array of signalling pathways, which are in turn influenced by a number of entities including epithelial mesenchymal transition (EMT), microRNAs (miRNAs), the tumour microenvironment and epigenetic modifications. Identification of CSCs commonly relies on the expression of specific cell surface markers, yet these markers vary between different malignancies and indeed are often co-expressed in non-neoplastic tissues. Development of targeted drug therapies against CSCs thus requires an understanding of disease-specific CSC markers and regulatory mechanisms. This review details the current knowledge regarding CSCs in GEJA, with particular emphasis on their role in drug resistance.

No Barrett's-No Cancer: A Proposed New Paradigm for Prevention of Esophageal Adenocarcinoma

Esophageal adenocarcinoma is inflammation-associated cancer with a recognizable preneoplastic stage, Barrett's. Barrett's describes the metaplastic transformation of esophageal squamous mucosa into columnar epithelium that typically results secondary to mucosal damage caused by acidic gastroduodenal reflux. Continued acid reflux may then result in mucosal inflammation which results in progressive inflammation-induced genetic instability that may eventuate in esophageal adenocarcinoma. Barrett's is the only recognized precursor lesion to esophageal carcinoma. Barrett's mucosa is unique among preneoplastic lesions; ablation therapy results in restitution of a squamous epithelium reducing or eliminating accumulated genetic instabilities and resetting the biological clock progressing toward invasive cancer. However, recurrence of Barrett's after ablation is common. We propose that both Barrett's and recurrence of Barrett's after ablation can be prevented and discuss how current approaches to therapy for gastroesophageal reflux disease, for Barrett's screening, chemoprevention, and ablation therapy all might be reconsidered. We propose (1) improved approaches to Barrett's prevention, (2) universal Barrett's screening by linking Barrett's screening to colon cancer screening, (3) ablation of all Barrett's mucosa along with (4) acid-suppressive-antireflux therapy tailored to prevent development of Barrett's or the recurrence of Barrett's after ablation therapy. We propose that ultimately, treatment decisions for gastroesophageal reflux disease and prevention of Barrett's and esophageal carcinoma should be based on assessing and maintaining esophageal mucosal integrity. This will require development and verification of specific measurements that reliably correlate with prevention of Barrett's. We outline the new research and technical advances needed to cost-effectively achieve these goals.

Pathogenesis and Cells of Origin of Barrett's Esophagus

In patients with Barrett's esophagus (BE), metaplastic columnar mucosa containing epithelial cells with gastric and intestinal features replaces esophageal squamous mucosa damaged by gastroesophageal reflux disease. This condition is estimated to affect 5.6% of adults in the United States, and is a major risk factor for esophageal adenocarcinoma. Despite the prevalence and importance of BE, its pathogenesis is incompletely understood and there are disagreements over the cells of origin. We review mechanisms of BE pathogenesis, including transdifferentiation and transcommitment, and discuss potential cells of origin, including basal cells of the squamous epithelium, cells of esophageal submucosal glands and their ducts, cells of the proximal stomach, and specialized populations of cells at the esophagogastric junction (residual embryonic cells and transitional basal cells). We discuss the concept of metaplasia as a wound-healing response, and how cardiac mucosa might be the precursor of the intestinal metaplasia of BE. Finally, we discuss shortcomings in current diagnostic criteria for BE that have important clinical implications.

Esophageal Cancer: Genomic and Molecular Characterization, Stem Cell Compartment and Clonal Evolution

Esophageal cancer (EC) is the eighth most common cancer and is the sixth leading cause of death worldwide. The incidence of histologic subtypes of EC, esophageal adenocarcinoma (EAC) and esophageal squamous carcinoma (ESCC), display considerable geographic variation. EAC arises from metaplastic Barrett's esophagus (BE) in the context of chronic inflammation secondary to exposure to acid and bile. The main risk factors for developing ESCC are cigarette smoking and alcohol consumption. The main somatic genetic abnormalities showed a different genetic landscape in EAC compared to ESCC. EAC is a heterogeneous cancer dominated by copy number alterations, a high mutational burden, co-amplification of receptor tyrosine kinase, frequent TP53 mutations. The cellular origins of BE and EAC are still not understood: animal models supported a cellular origin either from stem cells located in the basal layer of esophageal epithelium or from progenitors present in the cardia region. Many studies support the existence of cancer stem cells (CSCs) able to initiate and maintain EAC or ESCC. The exact identification of these CSCs, as well as their role in the pathogenesis of EAC and ESCC remain still to be demonstrated. The reviewed studies suggest that current molecular and cellular characterization of EAC and ESCC should serve as background for development of new treatment strategies.

Barrett's Esophagus: A Comprehensive and Contemporary Review for Pathologists

This review provides a summary of our current understanding of, and the controversies surrounding, the diagnosis, pathogenesis, histopathology, and molecular biology of Barrett's esophagus (BE) and associated neoplasia. BE is defined as columnar metaplasia of the esophagus. There is worldwide controversy regarding the diagnostic criteria of BE, mainly with regard to the requirement to histologically identify goblet cells in biopsies. Patients with BE are at increased risk for adenocarcinoma, which develops in a metaplasia-dysplasia-carcinoma sequence. Surveillance of patients with BE relies heavily on the presence and grade of dysplasia. However, there are significant pathologic limitations and diagnostic variability in evaluating dysplasia, particularly with regard to the more recently recognized unconventional variants. Identification of non-morphology-based biomarkers may help risk stratification of BE patients, and this is a subject of ongoing research. Because of recent achievements in endoscopic therapy, there has been a major shift in the treatment of BE patients with dysplasia or intramucosal cancer away from esophagectomy and toward endoscopic mucosal resection and ablation. The pathologic issues related to treatment and its complications are also discussed in this review article.

Oesophageal adenocarcinoma and gastric cancer: should we mind the gap?

Over recent decades we have witnessed a shift in the anatomical distribution of gastric cancer (GC), which increasingly originates from the proximal stomach near the junction with the oesophagus. In parallel, there has been a dramatic rise in the incidence of oesophageal adenocarcinoma (OAC) in the lower oesophagus, which is associated with antecedent Barrett oesophagus (BO). In this context, there has been uncertainty regarding the characterization of adenocarcinomas spanning the area from the lower oesophagus to the distal stomach. Most relevant to this discussion is the distinction, if any, between OAC and intestinal-type GC of the proximal stomach. It is therefore timely to review our current understanding of OAC and intestinal-type GC, integrating advances from cell-of-origin studies and comprehensive genomic alteration analyses, ultimately enabling better insight into the relationship between these two cancers.

The Barrett's Gland in Phenotype Space

Barrett's esophagus is characterized by the erosive replacement of esophageal squamous epithelium by a range of metaplastic glandular phenotypes. These glandular phenotypes likely change over time, and their distribution varies along the Barrett's segment. Although much recent work has addressed Barrett's esophagus from the genomic viewpoint-its genotype space-the fact that the phenotype of Barrett's esophagus is nonstatic points to conversion between phenotypes and suggests that Barrett's esophagus also exists in phenotype space. Here we explore this latter concept, investigating the scope of glandular phenotypes in Barrett's esophagus and how they exist in physical and temporal space as well as their evolution and their life history. We conclude that individual Barrett's glands are clonal units; because of this important fact, we propose that it is the Barrett's gland that is the unit of selection in phenotypic and indeed neoplastic progression. Transition between metaplastic phenotypes may be governed by neutral drift akin to niche turnover in normal and dysplastic niches. In consequence, the phenotype of Barrett's glands assumes considerable importance, and we make a strong plea for the integration of the Barrett's gland in both genotype and phenotype space in future work.

Barrett oesophagus: lessons on its origins from the lesion itself

Barrett oesophagus develops when the lower oesophageal squamous epithelium is replaced with columnar epithelium, which shows both intestinal and gastric differentiation. No consensus has been reached on the origin of Barrett oesophagus. Theories include a direct origin from the oesophageal-stratified squamous epithelium, or by proximal migration of the gastric cardiac epithelium with subsequent intestinalization. Variations of this theory suggest the origin is a distinctive cell at the squamocolumnar junction, the oesophageal gland ducts, or circulating bone-marrow-derived cells. Much of the supporting evidence comes from experimental models and not from studies of Barrett mucosa. In this Perspectives article, we look at the Barrett lesion itself: at its phenotype, its complexity, its clonal architecture and its stem cell organization. We conclude that Barrett glands are unique structures, but share many similarities with gastric glands undergoing the process of intestinal metaplasia. We conclude that current evidence most strongly supports an origin from stem cells in the cardia.

Squamous cell carcinoma after radiofrequency ablation for Barrett's dysplasia

Barrett's oesophagus (BO) is a usually indolent condition that occasionally requires endoscopic therapy. Radiofrequency ablation (RFA) is an effective endoscopic treatment for high grade dysplasia (HGD) and intramucosal cancer in BO. It has a good efficacy, durability and safety profile although complications can occur. Here we describe a case of RFA in a patient with high grade dysplasia. Although the response to treatment was initially very good with the development of neosquamous epithelium, the patient very rapidly developed a squamous cell cancer of the oesophagus confirmed on radiology, histology and immunohistochemistry. Sanger sequencing confirmed that the original HGD and the squamous cell cancer (SCC) were derived from separate clonal origins. The report highlights the fact that SCC of the oesophagus has been noted after endoscopic ablation for BO previously and suggest that ablation of BO may encourage the clonal expansion of cells carrying carcinogenic mutations once a dominant clonal population has been eradicated.

Immunohistochemical assessment of NY-ESO-1 expression in esophageal adenocarcinoma resection specimens

AIM: To assess NY-ESO-1 expression in a cohort of esophageal adenocarcinomas.

METHODS: A retrospective search of our tissue archive for esophageal resection specimens containing esophageal adenocarcinoma was performed, for cases which had previously been reported for diagnostic purposes, using the systematised nomenclature of human and veterinary medicine coding system. Original haematoxylin and eosin stained sections were reviewed, using light microscopy, to confirm classification and tumour differentiation. A total of 27 adenocarcinoma resection specimens were then assessed using immunohistochemistry for NY-ESO-1 expression: 4 well differentiated, 14 moderately differentiated, 4 moderate-poorly differentiated, and 5 poorly differentiated.

RESULTS: Four out of a total of 27 cases of esophageal adenocarcinoma examined (15%) displayed diffuse cytoplasmic and nuclear expression for NY-ESO-1. They displayed a heterogeneous and mosaic-type pattern of diffuse staining. Diffuse cytoplasmic staining was not identified in any of these structures: stroma, normal squamous epithelium, normal submucosal gland and duct, Barrett’s esophagus (goblet cell), Barrett’s esophagus (non-goblet cell) and high grade glandular dysplasia. All adenocarcinomas showed an unexpected dot-type pattern of staining at nuclear, paranuclear and cytoplasmic locations. Similar dot-type staining, with varying frequency and size of dots, was observed on examination of Barrett’s metaplasia, esophageal submucosal gland acini and the large bowel negative control, predominantly at the crypt base. Furthermore, a prominent pattern of apical (luminal) cytoplasmic dot-type staining was observed in some cases of Barrett’s metaplasia and also adenocarcinoma. A further morphological finding of interest was noted on examination of haematoxylin and eosin stained sections, as aggregates of lymphocytes were consistently noted to surround submucosal glands.

CONCLUSION: We have demonstrated for the first time NY-ESO-1 expression by esophageal adenocarcinomas, Barrett’s metaplasia and normal tissues other than germ cells.

How good is the neosquamous epithelium?

BACKGROUND/AIMS

Endoscopic radiofrequency ablation of dysplastic Barrett's esophagus (BE) combined with proton pump inhibitor therapy is commonly utilized for preventing progression of dysplastic BE to esophageal adenocarcinoma. Fundamental to the success of this and all ablative approaches is the healing of the ablated areas of BE with a stratified squamous epithelium referred to as 'neosquamous epithelium' (NSE). Although NSE appears 'normal' endoscopically, the reemergence of BE over time in the previously ablated segments raises the question of the health and integrity of NSE.

METHODS

The health of NSE was recently investigated in endoscopic biopsies in vitro in a group of patients after ablation while on proton pump inhibitors. Biopsies of NSE were compared to upper squamous epithelium (USE) from the same patients morphologically (light microscopy) and with respect to barrier function by measuring electrical resistance and fluorescein flux in mini-Ussing chambers.

RESULTS

Compared to USE, NSE exhibited dilated intercellular spaces and inflammation and defective barrier function by low electrical resistance and high fluorescein flux. Moreover, NSE exhibited downregulation of claudin-4, a highly expressed protein in squamous tight junctions.

CONCLUSION

NSE has defective barrier function in part due to downregulation of claudin-4. Since downregulation of claudin-4 increases paracellular permeability to cations, e.g. hydrogen ions, NSE is more vulnerable to attack and damage by acidic and weakly acidic refluxates--a phenomenon that may contribute in part to the reemergence of BE.

Clonal selection and persistence in dysplastic Barrett's esophagus and intramucosal cancers after failed radiofrequency ablation

OBJECTIVES

Radiofrequency ablation (RFA) is used to successfully eliminate Barrett's esophagus (BE)-related dysplasia or intramucosal carcinoma and aims to cause reversion to squamous epithelium. However, in 20% of cases RFA fails to return the epithelium to squamous phenotype. Follow-up studies show a similar dysplasia recurrence rate. We hypothesize that failed RFA is due to clonally mutated epithelial populations harbored in RFA-privileged sites and that RFA can select for the mutant clonal expansion.

METHODS

A longitudinal case series of 19 patients with BE and high-grade dysplasia or intramucosal carcinoma were studied. DNA was extracted from individual Barrett's glands, deep esophageal glands within mucosal resections and biopsy specimens before and after RFA. Mutations were identified by targeted sequencing of genes commonly mutated in Barrett's adenocarcinoma.

RESULTS

Five patients demonstrated persistent post-RFA pathology with persistent mutations, sometimes detected in deep esophageal glands or neighboring squamous epithelium after several rounds of RFA preceded by mucosal resection. Recurrence of pathology in three other patients was characterized by de novo mutations.

CONCLUSIONS

Protumorigenic mutations can be found in post-ablation squamous mucosa as well as in mutant deep esophageal glands; both are associated with dysplasia recurrence. Following RFA, non-dysplastic Barrett's epithelium can contain mutant clones that are found in a subsequent adenocarcinoma. Ablation may also drive the clonal expansion of pre-existing clones after a "bottleneck" created by the RFA. Overall, recurrence of dysplasia post RFA reflects the multicentric origins of Barrett's clones and highlights the role of clonal selection in carcinogenesis.

Bile acid at low pH reduces squamous differentiation and activates EGFR signaling in esophageal squamous cells in 3-D culture

BACKGROUND

Barrett's esophagus is a preneoplastic metaplasia in which the normal squamous epithelium of the esophagus changes to an intestinal, columnar phenotype due to long-term gastro-esophageal reflux. The major components of this reflux are bile and stomach acid. Previous in vitro studies on the effect of bile and acid on esophageal cells have predominantly relied on transformed esophageal squamous cells or cancer cells grown in monolayer culture.

DISCUSSION

In this study, we expanded our previous work using an immortalized primary esophageal squamous cell line (EPC1). We demonstrate that EPC1 cells form a multi-layer, stratified epithelium when grown on polyester transwell filters in media supplemented with calcium. When exposed to short pulses of bile and pH 5, but not either condition alone, EPC1 cells demonstrate a reduction in stratification layers and reduced expression of squamous epithelium-specific genes. Bile at pH 5 also causes activation of epidermal growth factor receptor and down-stream pathways. Blocking epidermal growth factor receptor activation partially attenuates the effects of bile acid and pH 5. These results suggest that bile at low pH, but not bile or low pH alone, promotes loss of differentiation status of stratified squamous esophageal epithelium in vitro, possibly by initiating a mucosal repair response through epidermal growth factor activation.

Esophageal squamous cell carcinoma arising after endoscopic ablation therapy of Barrett's esophagus with high-grade dysplasia. Report of a case

Patients with Barrett's esophagus are at risk for dysplasia and esophageal adenocarcinoma. Although surgery was the mainstay treatment for Barrett's dysplasia and cancer, patients with high-grade dysplasia and early cancers now have several nonsurgical treatment options. Most of the endoscopic therapies are relatively safe but do carry a risk for complications. Treatment failure with progression of the disease is the most severe complication, especially among patients with low surgical risk. Cryoablation has been used with promising results in both high-grade dysplasia and early esophageal cancer. A patient with a well-documented history of Barrett's esophagus with high-grade dysplasia that underwent multiple sessions of photodynamic therapy and salvage cryoablation for residual high-grade dysplasia was presented. The patient was diagnosed with squamous cell carcinoma of the distal esophagus approximately 1 year after cryoablation. This is the first complete report of squamous cell carcinoma occurring after endoscopic ablation for Barrett's neoplasia. Careful follow up is necessary in any endoscopic ablation program due to the risk of recurrent neoplasia.

Defective barrier function in neosquamous epithelium

OBJECTIVES

Radiofrequency ablation (RFA) of Barrett's esophagus (BE) is a common strategy for the prevention of esophageal adenocarcinoma (EAC). After RFA, the ablated esophagus heals on acid suppressive therapy, and is re-populated with a stratified squamous epithelium, referred to as "neosquamous epithelium (NSE)." Because the ability of the NSE to protect the underlying tissue from recurrent insult by reflux is unclear, we assessed the barrier function of NSE by comparing it to that of the native upper squamous epithelium (USE) in subjects having undergone RFA.

METHODS

At varying intervals following RFA, the barrier function of NSE and USE were assessed in endoscopic biopsies by light and electron microscopy, and by measurement of electrical resistance (R) and fluorescein flux in mini-Ussing chambers. Chamber results were further compared with results from control biopsies (healthy distal esophagus). A claudin expression profile in the tight junctions (TJs) of NSE and USE was determined using Quantitative reverse transcriptase PCR. Differential expression of claudin-4 between NSE and USE was assayed by immunoblots.

RESULTS

USE was histologically normal whereas NSE showed dilated intercellular spaces and marked eosinophilia. NSE was also more permeable than USE and healthy controls, having lower mean R and higher fluorescein fluxes. Abnormally low R values for NSE were unrelated to the time period following RFA (or number of prior RFA sessions), being abnormal even 26 months after RFA. Abnormal permeability in NSE was associated with significantly lower values for claudin-4 and claudin-10 than in USE.

CONCLUSIONS

NSE commonly exhibits defective barrier function. As this defect will make it vulnerable to injury, inflammation, and destruction by acidic and weakly acidic refluxates, it may in part explain incidences of recurrence of BE following ablation.

Molecular biomarkers and ablative therapies for Barrett's esophagus

Barrett's esophagus is the major risk factor for esophageal adenocarcinoma. Endoscopic interventions that ablate Barrett's esophagus mucosa lead to replacement with a new squamous (neosquamous) mucosa, but it can be difficult to achieve complete ablation. Knowing whether cancer is less likely to develop in neosquamous mucosa or residual Barrett's esophagus after ablation is critical for determining the efficacy of treatment. This issue can be informed by assessing biomarkers that are associated with an increased risk of progression to adenocarcinoma. Although there are few postablation biomarker studies, evidence suggests that neosquamous mucosa may have a reduced risk of adenocarcinoma in patients who have been treated for dysplasia or cancer, but some patients who do not have complete eradication of nondysplastic Barrett's esophagus may still be at risk. Biomarkers could be used to optimize endoscopic surveillance strategies following ablation, but this needs to be assessed by clinical studies and economic modeling.

Ablation of Barrett's oesophagus: towards improved outcomes for oesophageal cancer?

Barrett's oesophagus is the major risk factor for the development of oesophageal adenocarcinoma. The management of Barrett's oesophagus entails treating reflux symptoms with acid-suppressing medication or surgery (fundoplication). However, neither form of anti-reflux therapy produces predictable regression, or prevents cancer development. Patients with Barrett's oesophagus usually undergo endoscopic surveillance, which aims to identify dysplastic changes or cancer at its earliest stage, when treatment outcomes should be better. Alternative endoscopic interventions are now available and are suggested for the treatment of early cancer and prevention of progression of Barrett's oesophagus to cancer. Such treatments could minimize the risks associated with oesophagectomy. The current status of these interventions is reviewed. Various endoscopic interventions have been described, but with long-term outcomes uncertain, they remain somewhat controversial. Radiofrequency ablation of dysplastic Barrett's oesophagus might reduce the risk of cancer progression, although cancer development has been reported after this treatment. Endoscopic mucosal resection (EMR) allows a 1.5-2 cm diameter piece of oesophageal mucosa to be removed. This provides better pathology for diagnosis and staging, and if the lesion is confined to the mucosa and fully excised, EMR can be curative. The combination of EMR and radiofrequency ablation has been used for multifocal lesions, but long-term outcomes are unknown. The new endoscopic interventions for Barrett's oesophagus and early oesophageal cancer have the potential to improve clinical outcomes, although evidence that confirms superiority over oesphagectomy is limited. Longer-term outcome data and data from larger cohorts are required to confirm the appropriateness of these procedures.

Submucosal glands in the columnar-lined oesophagus: evidence of an association with metaplasia and neosquamous epithelium

AIM

A multipotential stem cell, possibly located in the submucosal gland ducts, has been suggested as the origin of metaplastic mucosa in the oesophagus. The topographic distribution of these glands and their excretory ducts (SMG) within the columnar lined oesophagus (CLO) is largely unknown. The aim of this study was to examine the distribution of SMG in relation to the type of overlying epithelium in patients with CLO.

METHODS AND RESULTS

Seven oesophageal resection specimens were examined histologically in toto. The median frequency of SMG was similar in the metaplastic segments (0.12 SMG/mm) and the normal squamous segments (0.10 SMG/mm). Within the metaplastic segments, the median frequency of SMG beneath the squamous islands was significantly higher than that observed under the columnar lined parts (0.22 versus 0.08 SMG/mm, P = 0.046), There was a strong accumulation of SMG at the squamo-columnar transition zones (0.53 SMG/mm), which was significantly greater than that found in the columnar and squamous parts (P = 0.001 and 0.002, respectively).

CONCLUSIONS

The relative accumulation of SMG beneath squamous islands and the squamo-columnar junctions within the metaplastic segment supports the hypothesis that both metaplastic columnar mucosa and neosquamous epithelium originate from a progenitor in the SMG.

Cyclooxygenase-2 expression in esophageal epithelium before and after photodynamic therapy for Barrett's esophagus with high-grade dysplasia or intramucosal carcinoma

Cyclooxygenase-2 expression is upregulated in Barrett's esophagus and esophageal adenocarcinoma. Photodynamic therapy using porfimer sodium can result in ablation of dysplasia and intramucosal carcinoma, eradication of Barrett's esophagus, and restitution of squamous epithelium. The aim of this study was to determine the effect of photodynamic therapy on cyclooxygenase-2 expression in esophageal epithelium. Paired pre- and post-photodynamic therapy biopsy samples from the same anatomical levels of 20 individuals who had undergone photodynamic therapy for Barrett's esophagus with high-grade dysplasia and/or intramucosal carcinoma were immunostained using a cyclooxygenase-2 monoclonal antibody. Cyclooxygenase-2 expression was graded in squamous epithelium, Barrett's esophagus, and neoplasia (if present) as follows: grade 0 (no staining), grade 1 (staining in 1-10% of cells), grade 2 (staining in 11-90% of cells), and grade 3 (staining in >90% of cells). Pre-photodynamic therapy median cyclooxygenase-2 expression was grade 2 (range 1-3) in neoplastic foci and grade 1 (range 1-3) in nondysplastic Barrett's esophagus (P=0.0009 for pairwise comparison). With the exception of a few cells staining in the basal epithelial layers, median cyclooxygenase-2 expression was graded as 0 (similar to controls) in both pre-photodynamic therapy squamous epithelium and post-photodynamic therapy neosquamous epithelium. This was significantly lower when compared to either neoplastic foci (P<0.0001) or nondysplastic Barrett's esophagus (P<0.0001) pre-photodynamic therapy. Notably, in four patients with post-photodynamic therapy recurrent neoplasia, cyclooxygenase-2 expression returned to elevated levels. Cyclooxygenase-2 expression is elevated in Barrett's esophagus with high-grade dysplasia or intramucosal carcinoma prior to photodynamic therapy. Following successful photodynamic therapy, cyclooxygenase-2 expression in neosquamous epithelium returns to a low baseline level similar to that observed in native esophageal squamous epithelium. Post-photodynamic therapy neoplastic recurrence is associated with elevated cyclooxygenase-2 expression. Prospective studies should determine whether cyclooxygenase inhibitors have a role as adjuvant therapy to prevent recurrence of Barrett's esophagus following endoscopic therapy.

An in vitro co-culture model of esophageal cells identifies ascorbic acid as a modulator of cell competition

Background

The evolutionary dynamics between interacting heterogeneous cell types are fundamental properties of neoplastic progression but can be difficult to measure and quantify. Cancers are heterogeneous mixtures of mutant clones but the direct effect of interactions between these clones is rarely documented. The implicit goal of most preventive interventions is to bias competition in favor of normal cells over neoplastic cells. However, this is rarely explicitly tested. Here we have developed a cell culture competition model to allow for direct observation of the effect of chemopreventive or therapeutic agents on two interacting cell types. We have examined competition between normal and Barrett's esophagus cell lines, in the hopes of identifying a system that could screen for potential chemopreventive agents.

Methods

One fluorescently-labeled normal squamous esophageal cell line (EPC2-hTERT) was grown in competition with one of four Barrett's esophagus cell lines (CP-A, CP-B, CP-C, CP-D) under varying conditions and the outcome of competition measured over 14 days by flow cytometry.

Results

We demonstrate that ascorbic acid (vitamin C) can help squamous cells outcompete Barrett's cells in this system. We are also able to show that ascorbic acid's boost to the relative fitness of squamous cells was increased in most cases by mimicking the pH conditions of gastrointestinal reflux in the lower esophagus.

Conclusions

This model is able to integrate differential fitness effects on various cell types, allowing us to simultaneously capture effects on interacting cell types without having to perform separate experiments. This model system may be used to screen for new classes of cancer prevention agents designed to modulate the competition between normal and neoplastic cells.

Role of Confocal Laser Endomicroscopy in Detection of Residual Barrett's Esophagus after Radiofrequency Ablation

Endoscopic endoluminal radiofrequency ablation (RFA) is a novel and promising modality for Barrett's esophagus (BE) treatment. Actually the only surveillance method after the ablation treatment is random biopsies throughout the whole treated area. Confocal laser endomicroscopy (CLE) is a new endoscopic imaging tool that permits high-resolution microscopic examination of the gastrointestinal tract. The technology has garnered increasing attention because of its ability to provide real-time "optical" biopsy specimens, with a very high sensitivity and specificity. This paper summarize the potential application of CLE in the surveillance of the reepithelialization of BE, after endoscopic RFA.

Does ablative therapy for Barrett esophagus affect the depth of subsequent esophageal biopsy as compared with controls?

BACKGROUND

Photodynamic therapy (PDT) and radiofrequency ablation (RFA) are associated with high rates of complete eradication of Barrett esophagus (BE). However, if ablation were to induce fibrosis in the regenerated squamous epithelium, then postablation biopsies may not penetrate deeply enough to detect subsquamous intestinal metaplasia (SSIM) and, therefore, complete response rates could be over-estimated.

GOALS

To assess the depth of esophageal biopsies from the squamous epithelium of ablation-naive controls and from the neosquamous epithelium of post-PDT and post-RFA patients to determine if prior ablation results in a reduced proportion of biopsies containing lamina propria (LP) as compared with controls.

STUDY

Review of archived esophageal specimens from a prospective multicenter cohort study (post-RFA) and 2 retrospective consecutive case series (ablation-naive controls, post-PDT).

SETTING

Eight US centers and 1 US gastrointestinal pathology laboratory.

PATIENTS

Ablation-naive controls with GERD, dyspepsia, and/or BE. Post-PDT and post-RFA BE patients with biopsies more than 6 months after achieving complete eradication of BE.

INTERVENTIONS

Review of endoscopic biopsies from ablation-naive controls, post-PDT patients, and post-RFA patients.

MAIN OUTCOME MEASUREMENTS

One GI pathology lab processed all tissue and slides. One expert GI pathologist, blinded to cohort, graded the depth of each esophageal specimen as: partial epithelium, full epithelium, LP, muscularis mucosae, or submucosa. Each specimen was also evaluated for SSIM.

RESULTS

There were 82 patients [ablation-naive (12), post-PDT (10), post-RFA (60)] with 899 biopsy specimens. The proportion of specimens containing "LP or deeper" was similar between groups: ablation-naive (88%), post-PDT (88%), post-RFA (91%) (P>0.05). No SSIM was detected in any group.

CONCLUSIONS

There is no difference in esophageal biopsy depth between ablation-naive squamous epithelium and post-PDT/post-RFA neo-squamous epithelium, thus refuting the concern of ablation-induced mucosal resistance to procurement of adequate biopsy specimens. Most biopsies (88% to 91%) from both ablation cohorts were deep enough to detect SSIM, in that they included "LP or deeper."

Effects of Nissen fundoplication on endoscopic endoluminal radiofrequency ablation of Barrett's esophagus

BACKGROUND

Endoscopic endoluminal radiofrequency ablation is achieving increasing acceptance as a mode of eliminating Barrett's metaplasia and, thus, reducing the risk of developing esophageal adenocarcinoma. It is believed that reducing exposure of the esophageal epithelium to acid is essential to achieve long-term ablation of Barrett's esophagus. However, it is unclear whether use of proton pump inhibitors or antireflux operations are more effective to accomplish this goal.

METHODS

All patients who underwent endoscopic endoluminal radiofrequency ablation with the BARRx device (BARRx Medical, Sunnyvale, CA) were reviewed for date of initial ablation, length of Barrett's epithelium, presence or performance of Nissen fundoplication, all follow-up endoscopy and treatment, and posttreatment biopsy results. Patients were categorized by presence of Nissen fundoplication and presence of Barrett's metaplasia or dysplasia by biopsy at least 12 months following ablation and at last endoscopic follow-up. Data were analyzed by Fisher's exact test and Mann-Whitney U-test.

RESULTS

Of 77 patients ablated, 47 had documented endoscopic follow-up at 12 months or longer following the ablation. Of these, 19 patients had Nissen fundoplication before, at the same time, or after ablation. Median length of Barrett's epithelium, with interquartile range (IQR), was 3 (2-12) cm in patients with fundoplication compared with 3 (2-7) cm without fundoplication (P = NS). Median follow-up was 15 (12-24) months in fundoplication patients compared with 12.5 (12-17) months without (P = NS). One of 19 patients with fundoplication had persistent or recurrent Barrett's epithelium, compared with 7 of 28 without fundoplication (P = 0.03). Of patients without fundoplication, those who had persistent or recurrent Barrett's had median Barrett's length of 10 cm (6-12 cm) compared with 3 cm (2-5 cm) in patients who had ablated Barrett's (P = 0.03). Follow-up length was similar in those with ablated epithelium, 15 months (12-19 months), compared with those with persistent or recurrent Barrett's, 12 months (12-13 months) (P = NS).

CONCLUSIONS

Patients who had fundoplication in conjunction with endoluminal radiofrequency ablation were more likely to achieve durable ablation compared with patients who were treated with proton pump inhibitor therapy. It appears that patients with long-segment Barrett's esophagus are at higher risk for persistent or recurrent Barrett's metaplasia. Consideration should be given for an antireflux operation in patients with long-segment Barrett's esophagus and planned endoluminal radiofrequency ablation.

The case for endoscopic treatment of non-dysplastic and low-grade dysplastic Barrett's esophagus

Non-dysplastic mucosa (ND-) in Barrett's esophagus (BE) shows clonal molecular aberrations, loss of cell cycle control, and other features of "neoplasia." These changes occur prior to morphologic expression of neoplasia (dysplasia). Morphologic evaluation of dysplasia is fraught with error, and, as a result, often leads to false-negative and false-positive diagnoses. Early "crypt dysplasia" is difficult to detect, and is often missed in routine biopsy specimens. Some studies show substantial progression rates of low-grade dysplasia (LGD), and crypt dysplasia, to esophageal adenocarcinoma (EAC). Dysplasia, even when fully developed, may, in certain circumstances, be difficult to differentiate from non-dysplastic (regenerating) BE. Radiofrequency ablation (RFA) is a safe and effective method for removing mucosa at risk of cancer. Given the difficulties of dysplasia assessment in mucosal biopsies, and the molecular characteristics of ND-BE, this technique should be considered for treatment of all BE patients, including those with ND or LGD. Post-ablation neo-squamous epithelium reveals no molecular abnormalities, and is biologically stable. Given that prospective randomized controlled trials of ablative therapy for ND-BE aiming at reducing EAC incidence and mortality are unlikely to be completed in the near future, endoscopic ablation is a valid management option. The success of RFA in achieving safe, uniform, reliable, and predictable elimination of BE allows surgeons to combine fundoplication with RFA. Currently, there is no type of treatment for dysplastic or non-dysplastic BE that achieves a complete response in 100% of patients, eliminates all risk of developing cancer, results in zero adverse events, is less expensive in terms of absolute costs than surveillance, is durable for 20+ years, or eliminates the need for surveillance. Regardless, RFA shows established safety, efficacy, durability, and cost-effective profiles that should be considered in the management of patients with non-dysplastic or low-grade dysplastic BE.

Cellular origin of Barrett's metaplasia and oesophageal stem cells

Barrett's oesophagus is a metaplastic pre-malignant disorder and the only established precursor lesion for oesophageal adenocarcinoma. Barrett's oesophagus develops when the normal stratified squamous epithelium of the lower oesophagus is replaced by a columnar lined mucosa with intestinal differentiation, usually in the context of chronic gastro-oesophageal reflux disease. The cellular and molecular mechanisms by which this metaplastic transformation occurs are poorly understood. Abnormal differentiation of multipotent stem cells in the squamous oesophagus, triggered by exposure to refluxate, is one potential mechanism. These stem cells could be located in the basal layer of the squamous oesophageal epithelium and/or in the neck region of the oesophageal submucosal gland ducts; however, their exact location and identification are still matter of discussion. Three-dimensional models combined with state-of-the-art imaging techniques are now applied to characterize the squamous epithelium in human oesophageal samples, and this could unveil essential information to identify these progenitor cells. Locating stem cells in human squamous oesophagus could have important implications for our understanding of Barrett's oesophagus and remarkably improve our future strategies for its prevention.

Endoscopic therapy using radiofrequency ablation for esophageal dysplasia and carcinoma in Barrett's esophagus

Radiofrequency ablation (RFA) is a novel and promising treatment modality for treatment of Barrett's esophagus (BE) with high-grade dysplasia or early carcinoma. RFA can be used as a single-modality therapy for flat-type mucosa or as a supplementary therapy after endoscopic resection of visible abnormalities. The treatment protocol consists of initial circumferential ablation using a balloon-based electrode, followed by focal ablation of residual Barrett's epithelium. RFA is less frequently associated with stenosis and buried glandular mucosa as are other ablation techniques and has shown to be safe and effective in the treatment of patients with BE and early neoplasia. In this article, the technical background, current clinical experience, and future prospects of RFA are evaluated.

Properties of the neosquamous epithelium after radiofrequency ablation of Barrett's esophagus containing neoplasia

OBJECTIVES

Endoscopic radiofrequency ablation (RFA) eradicates intestinal metaplasia and intraepithelial neoplasia associated with Barrett's esophagus (BE), restoring an endoscopically normal neosquamous epithelium (NSE). We evaluated the post-RFA NSE for genetic abnormalities and buried glandular mucosa.

METHODS

Eligible patients underwent RFA for BE containing early cancer and/or high-grade intraepithelial neoplasia with subsequent complete histological reversion to normal NSE. At baseline, the BE was sampled by brush cytology and biopsies. At least 2 months after RFA, the NSE was sampled by brush cytology, keyhole biopsies, and endoscopic resection. The untreated squamous epithelium was biopsied as a control. The baseline BE and post-RFA NSE were evaluated for immunohistochemical expression of Ki-67 and p53, and genetic abnormalities (DNA-fluorescent in situ hybridization: chromosome 1 and 9, p16 and p53). In addition, biopsy depth was compared for biopsies from the NSE and untreated squamous epithelium. The presence of buried glandular mucosa in NSE was assessed with primary and keyhole biopsy, and endoscopic resection.

RESULTS

All pretreatment specimens from all 22 patients showed abnormalities on immunohistochemical staining and fluorescent in situ hybridization, whereas all post-RFA NSE specimens were normal. All the post-RFA biopsies from the NSE contained full epithelia, whereas 37% contained lamina propria, a finding no different from biopsies from untreated squamous epithelium (36% lamina propria). Deeper keyhole biopsies contained lamina propria in 51%. All endoscopic resection specimens contained submucosa, whereas no biopsy or endoscopic resection specimen contained buried glandular mucosa.

CONCLUSIONS

Rigorous evaluation of the post-RFA NSE in patients who, at baseline, had BE containing early cancer high-grade intraepithelial neoplasia, showed neither persistent genetic abnormalities nor buried glandular mucosa.

MicroRNA-143 and -205 expression in neosquamous esophageal epithelium following Argon plasma ablation of Barrett's esophagus

INTRODUCTION

Ablation of Barrett's esophagus using Argon plasma coagulation (APC) is usually followed by the formation of a neosquamous epithelium. Investigating simple columnar or stratified squamous epithelium associated cytokeratin and microRNA (miRNA) expression in neo-squamous epithelium could help determine the identity and stability of the neosquamous epithelium.

METHODS

Nine patients underwent ablation of Barrett's esophagus with APC. Biopsies were collected from Barrett's esophagus mucosa and proximal normal squamous epithelium before ablation, and from neosquamous and normal squamous epithelium after ablation. Additional esophageal mucosal biopsies from ten nonrefluxing subjects were used as a reference. RNA was extracted and real-time polymerase chain reaction was used to measure the expression of the cytokeratins CK-8 and CK-14 and the microRNAs miR-143 and miR-205.

RESULTS

CK-8 and miR-143 expression were significantly higher in Barrett's esophagus mucosa, compared to neosquamous and normal squamous epithelium before and after APC, whereas miRNA-205 and CK-14 expression was significantly lower in Barrett's esophagus mucosa compared to all categories of squamous mucosa. The expression of CK-8, CK-14, miR-205, and miR-143 was similar between neosquamous epithelium compared to normal squamous epithelium in patients with Barrett's esophagus. Only miR-143 expression was significantly higher in neosquamous and normal squamous epithelium before and after APC compared to normal squamous epithelium from control subjects (p < 0.004).

CONCLUSIONS

The expression levels of cytokeratins and miRNAs studied in post-ablation neosquamous epithelium and normal squamous epithelium in patients with Barrett's esophagus are similar. In patients with Barrett's esophagus, miR-143 expression is still elevated in both neosquamous mucosa, and the squamous mucosa above the metaplastic segment, suggesting that this mucosa may not be normal; i.e., it is different to that seen in subjects without Barrett's esophagus. miR-143 could promote a Barrett's epithelium gene expression pattern, and this could have a role in development of Barrett's esophagus.

Cancer research meets evolutionary biology

There is increasing evidence that Darwin's theory of evolution by natural selection provides insights into the etiology and treatment of cancer. On a microscopic scale, neoplastic cells meet the conditions for evolution by Darwinian selection: cell reproduction with heritable variability that affects cell survival and replication. This suggests that, like other areas of biological and biomedical research, Darwinian theory can provide a general framework for understanding many aspects of cancer, including problems of great clinical importance. With the availability of raw molecular data increasing rapidly, this theory may provide guidance in translating data into understanding and progress. Several conceptual and analytical tools from evolutionary biology can be applied to cancer biology. Two clinical problems may benefit most from the application of Darwinian theory: neoplastic progression and acquired therapeutic resistance. The Darwinian theory of cancer has especially profound implications for drug development, both in terms of explaining past difficulties, and pointing the way toward new approaches. Because cancer involves complex evolutionary processes, research should incorporate both tractable (simplified) experimental systems, and also longitudinal observational studies of the evolutionary dynamics of cancer in laboratory animals and in human patients. Cancer biology will require new tools to control the evolution of neoplastic cells.

Stepwise radical endoscopic resection of the complete Barrett's esophagus with early neoplasia successfully eradicates pre-existing genetic abnormalities

OBJECTIVES

Malignant transformation of Barrett's mucosa is associated with the accumulation of genetic alterations. Stepwise radical endoscopic resection of the Barrett's segment with early neoplasia is a promising new treatment resulting in complete re-epithelialization of the esophagus with neosquamous epithelium. It is unknown whether radical resection also eradicates genetic abnormalities. The aim of this study was to prospectively evaluate whether genetic abnormalities as found in the Barrett's segment before radical resection are effectively eradicated and absent in the neosquamous epithelium.

METHODS

Nine patients with early neoplasia who successfully underwent radical resection were included. Immunohistochemistry (IHC) was performed to assess p53 protein overexpression. DNA fluorescent in-situ hybridization was (DNA-FISH) performed for evaluation of numerical abnormalities of chromosomes 1 and 9, and losses of p16 and p53. Immunohistochemistry and DNA-FISH were performed on endoscopic resection specimens of the neoplasia and on follow-up biopsies of the neosquamous epithelium.

RESULTS

DNA-FISH and IHC showed alterations in the pretreatment samples of all patients. All showed aneusomy of chromosome 1 and 9. Loss of p16 and p53 were seen in 6 and 8 patients. IHC showed intense p53 nuclear staining in seven patients. Post-treatment biopsies showed neosquamous epithelium with a normal diploid signal count for all DNA-FISH probes and normal IHC stainings in all patients.

CONCLUSIONS

Radical resection of Barrett's esophagus with early neoplasia successfully eradicates pre-existing genetic abnormalities and results in neosquamous epithelium without these genetic abnormalities.