Resection and advancement of esophageal mucosa. A potential therapy for Barrett's esophagus

Regenerative Medicine Strategies for Esophageal Repair

Pathologies that involve the structure and/or function of the esophagus can be life-threatening. The esophagus is a complex organ comprising nonredundant tissue that does not have the ability to regenerate. Currently available interventions for esophageal pathology have limited success and are typically associated with significant morbidity. Hence, there is currently an unmet clinical need for effective methods of esophageal repair. The present article presents a review of esophageal disease along with the anatomic and functional consequences of each pathologic process, the shortcomings associated with currently available therapies, and the latest advancements in the field of regenerative medicine with respect to strategies for esophageal repair from benchtop to bedside.

Treatment for Barrett's oesophagus

BACKGROUND

Treatments for Barrett's oesophagus, the precursor lesion of adenocarcinoma, are available but whether these therapies effectively prevent the development of adenocarcinoma, and in some cases eradicate the Barrett's oesophagus segment, remains unclear.

OBJECTIVES

To summarise, quantify and compare the efficacy of pharmacological, surgical and endoscopic treatments for the eradication of dysplastic and non-dysplastic Barrett's oesophagus and prevention of these states from progression to adenocarcinoma.

SEARCH STRATEGY

We searched CENTRAL (The Cochrane Library 2004, issue 4), MEDLINE (1966 to June 2008) and EMBASE (1980 to June 2008).

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing medical, endoscopic or non-resectional surgical treatments for Barrett's oesophagus. The primary outcome measures were complete eradication of Barrett's and dysplasia at 12 months, and reduction in the number of patients progressing to cancer at five years or latest time point.

DATA COLLECTION AND ANALYSIS

Three authors independently extracted data and assessed the quality of the trials included in the analysis.

MAIN RESULTS

Sixteen studies, including 1074 patients, were included. The mean number of participants in the studies was small (n = 49; range 8 to 208). Most studies did not report on the primary outcomes. Medical and surgical interventions to reduce symptoms and sequelae of gastro-oesophageal reflux disease (GORD) did not induce significant eradication of Barrett's oesophagus or dysplasia. Endoscopic therapies (photodynamic therapy (PDT with aminolevulinic acid or porfimer sodium), argon plasma coagulation (APC) and radiofrequency ablation (RFA)) all induced regression of Barrett's oesophagus and dysplasia. The data for photodynamic therapy were heterogeneous with a mean eradication rate of 51% for Barrett's oesophagus and between 56% and 100% for dysplasia, depending on the treatment regimens. The variation in photodynamic therapy eradication rates for dysplasia was dependent on the drug, source and dose of light. Radiofrequency ablation resulted in eradication rates of 82% and 94% for Barrett's oesophagus and dysplasia respectively, compared to a sham treatment. Endoscopic treatments were generally well tolerated, however all were associated with some buried glands, particularly following argon plasma coagulation and photodynamic therapy, as well as photosensitivity and strictures induced by porfimer sodium based photodynamic therapy in particular.

AUTHORS' CONCLUSIONS

Despite their failure to eradicate Barrett's oesophagus, the role of medical and surgical interventions to reduce the troubling symptoms and sequelae of GORD is not questioned. Whether therapies for GORD reduce the cancer risk is not yet known. Ablative therapies have an increasing role in the management of dysplasia within Barrett's and current data would favour the use of radiofrequency ablation compared with photodynamic therapy. Radiofrequency ablation has been shown to yield significantly fewer complications than photodynamic therapy and is very efficacious at eradicating both dysplasia and Barrett's itself. However, long-term follow-up data are still needed before radiofrequency ablation can be used in routine clinical care without the need for very careful post-treatment surveillance. More clinical trial data and in particular randomised controlled trials are required to assess whether or not the cancer risk is reduced in routine clinical practice.

Endoscopic approaches to Barrett's oesophagus with high-grade dysplasia/early mucosal cancer

This chapter will review the endoscopic approaches to the management of Barrett's oesophagus with high-grade dysplasia/early mucosal cancer. Factors to consider when evaluating patients for endoscopic management are detailed. Ablation and resection methods for eradication of Barrett's oesophagus with high-grade dysplasia/early mucosal cancer are reviewed. Strategies for combining therapies to achieve safe and effective eradication are discussed. Recommendations for complete eradication of all Barrett's mucosa and follow-up considerations are put forward.

Use of ethylenediaminetetraacetic acid for in vivo stripping of columnar mucosa: pilot study in an experimental model

BACKGROUND

Barrett's oesophagus is an important clinical problem that can lead to oesophageal adenocarcinoma. A variety of mucosal ablation strategies are now being applied in an attempt to prevent this, although they all can cause complications. Animal experiments that suggest that ethylenediaminetetraacetic acid (EDTA) could be a novel agent for ablation of Barrett's oesophagus are reported in this article.

METHODS

Dark Agouti rats were used in all experiments. To determine the feasibility of using EDTA to strip intestinal type mucosa, segments of the small intestine were exposed in vitro to EDTA at various concentrations with or without agitation. The conditions required for EDTA to strip mucosa from a vascularized loop of small bowel were then optimized in vivo. Cannulated small bowel loops were irrigated with different concentrations of EDTA with or without pulsation of the irrigation solution. The effect of similar treatments on the normal mucosa of the rat oesophagus was then determined. Mucosal healing after EDTA stripping was studied in an isolated small bowel loop survival model.

RESULTS

Ethylenediaminetetraacetic acid with agitation or pulsation resulted in stripping of the intestinal columnar mucosa in vitro and in vivo. The extent was influenced by the concentration of EDTA and duration of exposure. Squamous epithelium was relatively resistant to stripping. In the survival model the small bowel mucosa regenerated without stricture formation.

CONCLUSION

Small bowel columnar mucosa can be removed by EDTA in vivo without stricture formation. A refinement of this approach could be applicable to the ablation of Barrett's oesophagus.

Ablative procedures for prevention and treatment of esophageal adenocarcinoma

Ablation of Barrett's mucosa by endoscopic resection, photodynamic therapy or thermoablative methods in combination with adequate acid suppression leads to mucosal replacement largely by squamous epithelium. In appropriately selected cases, these methods have the potential to cure superficial Barrett's neoplasia. Endoscopic resection is an alternative to surgical resection of high-grade intraepithelial neoplasia or early esophageal adenocarcinoma, if the tumor is less than 20 mm in size, is not ulcerated, and does not exhibit differentiation grade 3 or lymph vessel infiltration on histological examination. In the presence of submucosal infiltration, the likelihood of lymph node infiltration is related to the infiltration depth. The risk of a noncurative endoscopic ablative approach has to be weighted against the general risk of surgery. With photodynamic or thermoablative treatment, the completeness of destruction of neoplastic tissue can only be judged at follow-up. These methods are therefore restricted to cases that have an increased surgical risk. Ablation of non-neoplastic Barrett's mucosa is currently not indicated.

Endoscopic therapeutic esophageal interventions

In Western countries, many esophageal diseases result from uncontrolled gastroesophageal reflux. Treatments for Barrett esophagus, peptic strictures, and esophageal adenocarcinoma still account for a large portion of the esophageal interventions performed by therapeutic endoscopists. In addition to continued refinements in the treatment of these sequelae, new endoscopic therapies have emerged to treat gastroesophageal reflux disease itself. This article reviews the available literature on new endoscopic antireflux procedures along with other advances that give the endoscopist unprecedented options in the treatment of esophageal diseases.