Barrett's oesophagus length is established at the time of initial endoscopy and does not change over time: results from a large multicentre cohort

Etiologic factors for Barrett's esophagus: toward countermeasures in Asia

INTRODUCTION

Over the past several decades, Europe and the United States have experienced a rapid increase in esophageal adenocarcinoma. Research and countermeasures against Barrett's esophagus, its precancerous lesion, are progressing. Because esophageal adenocarcinoma has an extremely poor prognosis when diagnosed in an advanced stage, recommendations for early cancer detection have been made based on the various proven etiological factors of Barrett's esophagus and the actual cancer risk of Barrett's esophagus. In recent years, there have been indications of an increase in esophageal adenocarcinoma in Japan, and a similar trend of cancer will occur shortly in other Asian countries. Consequently, Asian countries must implement similar countermeasures against Barrett's esophagus and esophageal adenocarcinoma, referencing the knowledge gained thus far in Europe and the United States.

AREAS COVERED

This review summarizes the latest findings on the etiologic factors of Barrett's esophagus and discusses the differences between Westerners and Asians. The current status of Barrett's esophagus in Japan and other Asian countries is also summarized.

EXPERT OPINION

The etiological factors and cancer incidence of Barrett's esophagus in Asia diverge somewhat from those observed in Europe and America. Therefore, it is imperative to implement measures that are tailored to the actual circumstances of Asian people.

Relationship between Helicobacter pylori Eradication and Barrett's Esophagus Elongation

INTRODUCTION

Helicobacter pylori eradication therapy may worsen gastroesophageal reflux disease that is a significant risk factor for Barrett's esophagus. However, the relationship between eradication therapy and Barrett's esophagus remains controversial. This study evaluated the impact of Helicobacter pylori eradication on the lengthening of Barrett's esophagus.

MATERIALS AND METHODS

We conducted a retrospective analysis of consecutive patients who successfully underwent Helicobacter pylori eradication between 2004 and 2017. Endoscopic images obtained before and after eradication therapy were compared for Barrett's esophagus length according to the Prague C&M criteria and the presence of reflux esophagitis based on the Los Angeles classification.

RESULTS

A total of 340 patients were analyzed (mean age: 66.9 ± 12.9 years) for a median follow-up of 55 months (interquartile range: 29.8-89.3). At the initial endoscopic assessment, 187 patients (55%) had a hiatal hernia, and all patients had gastric atrophy (C-0 to I: 2%, C-II to III: 47%, O-I to III: 51%). Reflux esophagitis was detected in 7 patients (2%) before eradication and in 21 patients (6%) afterward, which was a significant increase (p = 0.007). Barrett's esophagus was identified in 69 patients (20%) before eradication, with a median length of C0M1. Elongation after treatment was observed in only 2 patients (0.6%). We observed no significant increase in either the prevalence (p = 0.85) or the median length (p = 0.5) of Barrett's esophagus.

CONCLUSIONS

Only 0.6% of patients exhibited Barrett's esophagus lengthening after Helicobacter pylori eradication therapy, suggesting no significant impact of the treatment on the development or elongation of Barrett's esophagus.

Clinical characteristics may distinguish patients with esophageal adenocarcinoma arising from long- versus short-segment Barrett's esophagus

BACKGROUND AND AIMS

Patients with long-segment Barrett's esophagus (LSBE; ≧3 cm) have higher risk of developing esophageal adenocarcinoma (EAC) than those with short-segment Barrett's esophagus (SSBE; <3 cm). However, it is unclear whether patients developing EAC from LSBE or SSBE differ significantly according to baseline clinical characteristics.

METHODS

We conducted a retrospective analysis of a prospectively maintained database comprising consecutive patients with early EAC treated by endoscopic mucosal resection at a single, tertiary-referral center. Information regarding baseline clinical characteristics were determined. Univariate and multivariate logistic regression were performed to identify factors that differed significantly between patients with EAC arising from SSBE and LSBE.

RESULTS

A total of 145 LSBE EAC and 179 SSBE EAC cases were identified. The LSBE EAC patients had a stronger association with having a hiatal hernia compared to the SSBE EAC patients. In contrast, inverse associations were observed in LSBE EAC patients with statin use and smoking pack-years relative to SSBE EAC patients.

CONCLUSIONS

Patients who developed EAC on a background of LSBE were more likely to have a hiatus hernia compared to patients with SSBE EAC, who were more likely to have higher smoking pack-years and higher rates of statin use.

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.

Lower Annual Rate of Progression of Short-Segment vs Long-Segment Barrett's Esophagus to Esophageal Adenocarcinoma

BACKGROUND & AIMS

European guidelines recommend different surveillance intervals of non-dysplastic Barrett's esophagus (NDBE) based on segment length, as opposed to guidelines in the United States, which do recommend surveillance intervals based on BE length. We studied rates of progression of NDBE to high-grade dysplasia (HGD) or esophageal adenocarcinoma (EAC) in patients with short-segment BE using the definition of BE in the latest guidelines (length ≥1 cm).

METHODS

We collected demographic, clinical, endoscopy, and histopathology data from 1883 patients with endoscopic evidence of NDBE (mean age, 57.3 years; 83.5% male; 88.1% Caucasians) seen at 7 tertiary referral centers. Patients were followed for a median 6.4 years. Cases of dysplasia or EAC detected within 1 year of index endoscopy were considered prevalent and were excluded. Unadjusted rates of progression to HGD or EAC were compared between patients with short (≥1 and <3) and long (≥3) BE lengths using log-rank tests. A subgroup analysis was performed on patients with a documented Prague C&M classification. We used a multivariable proportional hazards model to evaluate the association between BE length and progression. Adjusted hazards ratios were calculated after adjusting for variables associated with progression.

RESULTS

We found 822 patients to have a short-segment BE (SSBE) and 1061 to have long segment BE (LSBE). We found patients with SSBE to have a significantly lower annual rate of progression to EAC (0.07%) than of patients with LSBE (0.25%) (P = .001). For the combined endpoint of HGD or EAC, annual progression rates were significantly lower among patients with SSBE (0.29%) compared to compared to LSBE (0.91%) (P < .001). This effect persisted in multivariable analysis (hazard ratio, 0.32; 95% CI, 0.18-0.57; P < .001).

CONCLUSION

We analyzed progression of BE (length ≥1 cm) to HGD or EAC in a large cohort of patients seen at multiple centers and followed for a median 6.4 years. We found a lower annual rate of progression of SSBE to EAC (0.07%/year) than of LSBE (0.25%/year). We propose lengthening current surveillance intervals for patients with SSBE.

Insights Into the Pathophysiology of Esophageal Adenocarcinoma

Although researchers have identified genetic alterations that contribute to development of esophageal adenocarcinoma, we know little about features of patients or environmental factors that mediate progression of chronic acid biliary reflux to Barrett's esophagus and cancer. Increasing our understanding of the mechanisms by which normal squamous epithelium progresses to early-stage invasive cancer will help formulate rational surveillance guidelines and allow us to divest resources away from patients at low risk of malignancy. We review the cellular and genetic alterations that occur during progression of Barrett's esophagus, based on findings from clinical studies and mouse models of disease. We review the features of the luminal and mucosal microenvironment of Barrett's esophagus that promote, in a small proportion of patients, development of esophageal adenocarcinoma. Markers of clonal evolution can be used to determine patient risk for cancer and set surveillance intervals.

Endoscopic risk factors for neoplastic progression in patients with Barrett's oesophagus

Barrett's oesophagus is a precursor lesion for oesophageal adenocarcinoma, which generally has a poor prognosis. Patients diagnosed with Barrett's oesophagus therefore undergo regular endoscopic surveillance to detect neoplastic lesions at a curable stage. The efficacy of endoscopic surveillance of Barrett's oesophagus patients is, however, hampered by difficulties to detect early neoplasia endoscopically, biopsy sampling error, inter-observer variability in histological assessment and the relatively low overall progression rate. Efficacy and cost-effectiveness of Barrett's surveillance may be improved by using endoscopic and clinical characteristics to risk-stratify Barrett's patients to high- and low-risk categories. Recent national and international surveillance guidelines have incorporated Barrett's length and presence of low-grade dysplasia in the advised surveillance intervals. In this review we will discuss endoscopic characteristics that may be associated with neoplastic progression in Barrett's oesophagus and that may be used to tailor surveillance in Barrett's patients.

The Complex, Clonal, and Controversial Nature of Barrett's Esophagus

Barrett's esophagus (BO) is a preneoplastic condition described as the replacement of the stratified squamous epithelium of the distal esophagus with one that histologically presents as a diverse mixture of metaplastic glands resembling gastric or intestinal-type columnar epithelium. The clonal origins of BO are still unclear. More recently, we have begun to investigate the relationship between the various metaplastic gland phenotypes observed in BO, how they evolve, and the cancer risk they bestow. Studies have revealed that glands along the BO segment are clonal units containing a single stem cell clone that can give rise to all the differentiated epithelial cell types in glands. Clonal lineage tracing analysis has revealed that Barrett's glands are capable of bifurcation and this facilitates clonal expansion and competition. In fact, BO in some patients appears to consist of multiple, independently initiated clones that compete with each other for space and possibly resources. This chapter discusses the concepts of clonal competition and expansion in BO and sets out to query what we know about the role of gland diversity and phenotypic evolution within this complex columnar metaplasia.