Review article: Barrett's oesophagus, dysplasia and pharmacologic acid suppression

Proton pump inhibitors may reduce the risk of high-grade dysplasia and/or esophageal adenocarcinoma in Barrett's esophagus: a systematic review and meta-analysis

BACKGROUND

Barrett's esophagus (BE) is an important risk factor for high-grade dysplasia (HGD) and/or esophageal adenocarcinoma (EAC). The effect of proton pump inhibitors (PPIs) on the chemoprevention of HGD and/or EAC arising from BE remains controversial.

RESEARCH DESIGN AND METHODS

PubMed, EMBASE, and Cochrane Library databases were systematically searched. Risk ratios (RRs) or odds ratios (ORs) with 95% confidence intervals (CIs) were pooled by a random-effect model. Heterogeneity and its potential source were assessed.

RESULTS

Fifteen studies with 26,291 BE patients were included. Meta-analysis of eight cohort studies showed that PPIs can significantly reduce the risk of HGD and/or EAC in BE patients (RR = 0.46; P < 0.001), but meta-analysis of six case-control studies showed no significant benefit of PPIs (OR = 0.64; P = 0.334). Heterogeneity was significant among both cohort and case-control studies, which might be attributed to the information sources of PPIs. There was no significant protective effect of high-dose PPIs on HGD and/or EAC in one RCT (RR = 0.84; P = 0.21), meta-analysis of two cohort studies (RR = 0.61; P = 0.28), or meta-analysis of two case-control studies (OR = 0.32; P = 0.08).

CONCLUSIONS

Chemoprevention of HGD and/or EAC by PPIs may be considered in BE patients. However, there might not be further preventive effect of high-dose PPIs.

Do proton pump inhibitors prevent Barrett's esophagus progression to high-grade dysplasia and esophageal adenocarcinoma? An updated meta-analysis

PURPOSE

Previous research on the association between proton pump inhibitor (PPI) use and the risk of progression to high-grade dysplasia (HGD)/esophageal adenocarcinoma (EAC) in Barrett's Esophagus (BE) patients has generated inconsistent findings. This meta-analysis was performed to clarify the association.

METHODS

We performed a comprehensive search strategy to select relevant studies up to September 2020. Heterogeneity was assessed using the I-squared statistic. Odds ratios (OR) and 95% confidence intervals (CI) were calculated through either fixed-effects or random-effects model. Duration-response was also performed to assess the gain effects of different PPI intake duration. Sensitivity analysis, subgroup analyses, and tests for publication bias or other small-study effects were conducted.

RESULTS

Twelve studies with 155,769 subjects were included. The PPI use was associated with the reduced risk of BE progression to HGD/EAC (OR = 0.47, 95% CI = 0.32-0.71). In the duration-response analysis, the estimated OR for decreased risk of HGD/EAC with PPI intake duration of 12 months was 0.81 (95% CI = 0.71-0.91). Sensitivity analysis suggested the results of this meta-analysis were stable. No publication bias was detected.

CONCLUSIONS

PPI use is associated with a decreased risk of HGD/EAC in patients with BE. For further investigation, that more well-designed studies are still needed to elucidate the protective effect of PPI usage on BE patients to prevent HGD/EAC.

Precision care for Barrett's esophagus

Modern recognition and management of Barrett's esophagus, a precursor to esophageal adenocarcinoma depends on diagnostic accuracy, risk assessment, technical expertise and consideration of many options to best tailor therapy for every patient. Concomitant management of acid reflux is essential, frequently with proton pump inhibitors. Ablation and resection favorably affect the evolution towards cancer. Using precision medicine tools, such as imaging, molecular diagnostics and analytics may lead to cost- and comparatively-effective therapies ultimately aiming at cancer prevention. Knowledge of the risk factors for Barrett's esophagus and progression to dysplasia and cancer can help tailor a precision medicine approach with more aggressive screening and surveillance targeted at patients that are most likely to benefit.

Strategy for prevention of cancers of the esophagus

The following, from the 12th OESO World Conference: Cancers of the Esophagus, includes commentaries on the animal reflux-inflammation models for Barrett's esophagus and esophageal adenocarcinoma; genomic/epigenomic analyses; eflornithine-based combinations; the molecular derangements that promote neoplastic transformation; the role of COX-2 inhibitors, proton pump inhibitors, and phase II trials in Barrett's adenocarcinoma; statins in chemoprevention and treatment of esophageal cancer; and biomarkers as potential targets in Barrett's adenocarcinoma.

Acid-suppressive medications and risk of oesophageal adenocarcinoma in patients with Barrett's oesophagus: a systematic review and meta-analysis

BACKGROUND AND AIMS

Acid-suppressive medications, particularly proton pump inhibitors (PPIs), may decrease the risk of oesophageal adenocarcinoma (OAC) in patients with Barrett's oesophagus (BO). We performed a systematic review with meta-analysis of studies evaluating the association between acid-suppressive medications (PPIs and histamine receptor antagonists (H2RAs)) and risk of OAC or high-grade dysplasia (BO-HGD) in patients with BO.

METHODS

We performed a systematic search of multiple electronic databases and conference proceedings up to June 2013 to identify studies reporting the association between use of acid-suppressive medications and risk of OAC and/or BO-HGD in patients with BO. Summary ORs with 95% CIs were estimated.

RESULTS

We identified seven observational studies (2813 patients with BO, 317 cases of OAC or BO-HGD, 84.4% PPI users). On meta-analysis, PPI use was associated with a 71% reduction in risk of OAC and/or BO-HGD in patients with BO (adjusted OR 0.29; 95% CI 0.12 to 0.79). There was a trend towards a dose-response relationship with PPI use for >2-3 years protective against OAC or BO-HGD (three studies; PPI use >2-3 years vs <2-3 years: OR 0.45 (95% CI 0.19 to 1.06) vs 1.09 (0.47 to 2.56)). Considerable heterogeneity was observed. Two studies reported the association between H2RA use and risk of OAC and/or BO-HGD (1352 patients with BO, 156 cases of OAC, 25.4% on H2RAs), and both studies did not show a significant effect.

CONCLUSIONS

Based on meta-analysis of observational studies, the use of PPIs is associated with a decreased risk of OAC and/or BO-HGD in patients with BO. None of the studies showed an increased risk of OAC. PPI use should be considered in BO, and chemopreventive trials of PPIs in patients with BO are warranted.

Proton pump inhibitor use may not prevent high-grade dysplasia and oesophageal adenocarcinoma in Barrett's oesophagus: a nationwide study of 9883 patients

BACKGROUND

Proton pump inhibitors (PPI) may potentially modify and decrease the risk for development of oesophageal adenocarcinoma in Barrett's oesophagus (BO).

AIM

To investigate if the intensity and adherence of PPI use among all patients with BO in Denmark affected the risk of oesophageal adenocarcinoma.

METHODS

We performed a nationwide case-control study in Denmark among 9883 patients with a new diagnosis of BO. All incident oesophageal adenocarcinomas and high-grade dysplasias were identified, and risk ratios were estimated on the basis of prior use of PPIs. Sex- and age-matched BO patients without dysplasia or malignancies in a 10:1 ratio were used for comparison. Conditional logistic regression was used for analysis, adjusting for low-grade dysplasia, gender and medication.

RESULTS

We identified 140 cases with incident oesophageal adenocarcinomas and/or high-grade dysplasia, with a median follow-up time of 10.2 years. The relative risk of oesophageal adenocarcinoma or high-grade dysplasia was 2.2 (0.7-6.7) and 3.4 (95% CI: 1.1-10.5) in long-term low- and high-adherence PPI users respectively.

CONCLUSIONS

No cancer-protective effects from PPI's were seen. In fact, high-adherence and long-term use of PPI were associated with a significantly increased risk of adenocarcinoma or high-grade dysplasia. This could partly be due to confounding by indication or a true negative effect from PPIs. Until the results from future studies hopefully can elucidate the association further, continuous PPI therapy should be directed at symptom control and additional modalities considered as aid or replacement.

Interobserver agreement for the detection of Barrett's esophagus with optical frequency domain imaging

BACKGROUND

Optical frequency domain imaging (OFDI) is a second-generation form of optical coherence tomography (OCT) providing comprehensive cross-sectional views of the distal esophagus at a resolution of ~7 μm.

AIM

Using validated OCT criteria for squamous mucosa, gastric cardia mucosa, and Barrett's esophagus (BE), the objective of this study was to determine the inter- and intra-observer agreements by a large number of OFDI readers for differentiating these tissues.

METHODS

OFDI images were obtained from nine subjects undergoing screening and surveillance for BE. Sixty-four OFDI image regions of interest were randomly selected for review. A training set of 19 images was compiled distinguishing squamous mucosa from gastric cardia and BE using previously validated OCT criteria. The ten readers then interpreted images in a test set of 45 different images of squamous mucosa (n = 15), gastric cardia (n = 15), or BE (n = 15). Interobserver agreement differentiating the three tissue types and BE versus non-BE mucosa was determined using multi-rater Fleiss's κ value. The images were later randomized again and four readers repeated the test 3 weeks later to assess intraobserver reliability.

RESULTS

All ten readers showed excellent agreement for the differentiation of BE versus non-BE mucosa (κ = 0.811 p < 0.0001) and for differentiating BE versus gastric cardia versus squamous mucosa (κ = 0.866, p < 0.0001). For the four readers who repeated the test, the median intraobserver agreement (BE vs. non-BE) was high (κ = 0.975, IQR: 0.94, 1.0).

CONCLUSIONS

Trained readers have a high interobserver agreement for differentiating BE, squamous, and gastric cardia mucosa using OFDI.

Upper gastrointestinal cancer and reflux disease

There is a growing evidence that gastroesophageal reflux disease is related to several upper gastrointestinal cancers, mainly the esophageal adenocarcinoma and a certain type of gastric cardia adenocarcinoma. Currently, the incidence of gastroesophageal reflux disease is rapidly increasing in Korea. Therefore, there is a possibility of such increasing cancerous incidents, similar to the western worlds. In this article, the relationship between gastroesophageal reflux disease and several upper gastrointestinal cancers, the components of refluxate which has possible causal relationship with carcinogenesis, and the clinical implications of such relationship in the management of gastroesophageal reflux disease patients are discussed through the review of literature.

Advanced esophageal cancer in patients who underwent radiofrequency ablation for barrett esophagus with high-grade dysplasia

OBJECTIVE

We sought to evaluate clinicopathologic features of patients who underwent esophageal surgery after radiofrequency ablation (RFA) treatment using the HALO system for Barrett esophagus (BE) with high-grade dysplasia (HGD).

METHODS

We evaluated patients from our hospital database who underwent esophagectomy from August 2006 to January 2012 after previously receiving RFA for BE. Information on demographics, time between RFA and surgery, indications for surgery, and final esophageal pathology was collected.

RESULTS

In our study, we selected 102 patients who underwent esophagectomy. Five patients had a history of RFA for BE with HGD. Three patients were referred because of persistent HGD despite RFA, and all three patients had HGD in the esophagectomy specimen. Two patients presented with a benign diagnosis (esophageal perforation and leiomyoma), and both of these patients had pathologic stage T3N2M0 adenocarcinoma of the esophagus in the resected specimen. One of these patients had normal mucosa overlying carcinoma in the muscularis propria and adventitia. The patients with stage T3N2M0 cancer did not have pre-RFA endoscopic ultrasound, first treatment of RFA with HALO, or surveillance endoscopic biopsy every 3 months.

CONCLUSIONS

Radiofrequency ablation for BE with HGD may mask underlying esophageal cancer. Patients who are counseled to undergo RFA for HGD should be aware that RFA could lead to delayed diagnosis and delayed treatment of invasive esophageal cancer without careful patient selection, appropriate RFA use, and close surveillance.

Optimal management of Barrett's esophagus: pharmacologic, endoscopic, and surgical interventions

Esophageal adenocarcinoma and its precursor, Barrett’s esophagus, are rapidly rising in incidence. This review serves to highlight the role of pharmacologic, endoscopic, and surgical intervention in the management of Barrett’s esophagus, which requires acid suppression and endoscopic assessment. Treatment with a proton pump inhibitor may decrease acid exposure and delay the progression to dysplasia. Patients who require aspirin for cardioprotection or other indications may also benefit in terms of a protective effect against the development of esophageal cancer. However, without other indications, aspirin is not indicated solely to prevent cancer. A careful endoscopic examination should include assessment of any visible lesions in a Barrett’s segment. An expert gastrointestinal pathologist should confirm neoplasia in the setting of Barrett’s esophagus. For those patients with high-grade dysplasia or intramucosal carcinoma, careful consideration of endoscopic therapy or surgical therapy must be given. All visible lesions in the setting of dysplasia should be targeted with focal endoscopic mucosal resection for both accurate histopathologic diagnosis and treatment. The remainder of the Barrett’s epithelium should be eradicated to address all synchronous and metachronous lesions. This may be done by tissue acquiring or nontissue acquiring means. Radiofrequency ablation has a positive benefit-risk profile for flat Barrett’s esophagus. At this time, endoscopic therapy is not indicated for nondysplastic Barrett’s esophagus. Esophagectomy is still reserved for selected cases with evidence of lymph node metastasis, unsuccessful endoscopic therapy, or with high-risk features of high-grade dysplasia or intramucosal carcinoma.

Chemoprevention in Barrett's oesophagus

Barrett's oesophagus normally affects the distal oesophagus when metaplastic columnar lined epithelium replaces stratified squamous epithelium which predisposes to cancer development. This develops as a consequence of chronic gastroesophageal reflux (GORD). Those with Barrett's have a 40 fold increased risk of oesophageal adenocarcinoma [1]. There are is still a lack of understanding of the natural history of the cell of origin. This does hamper research into this area. We accept that there is a limitation in testing of the pathogenesis of Barrett's oesophagus due to a lack of a universally accepted animal model. The major questions surrounding Barrett's oesophagus include validity of surveillance strategies, the optimal treatment and more importantly an agent that can prevent progression to cancer without unacceptable side effects. The main chemopreventative agents that show promise are aspirin and proton pump inhibitors (PPIs). There are other agents such as green tea, berries and antioxidants and diet that have been suggested; we discuss the evidence available for these strategies. We hope for continued improvement in the clinical trial infrastructure to facilitate testing of new pharmacological and endoscopic interventions for Barrett's oesophagus.

Barrett's esophagus: a review of the literature

Barrett's esophagus (BE) is the premalignant lesion of esophageal adenocarcinoma (EAC) defined as specialized intestinal metaplasia of the tubular esophagus that results from chronic gastroesophageal reflux. Which patients are at risk of having BE and which are at further risk of developing EAC has yet to be fully established. Many aspects of the management of BE have changed considerably in the past 5 years alone. The aim of this review is to define the critical elements necessary to effectively manage individuals with BE. The general prevalence of BE is estimated at 1.6-3% and follows a demographic distribution similar to EAC. Both short-segment (<3 cm) and long-segment (≥3 cm) BE confer a significant risk for EAC that is increased by the development of dysplasia. The treatment for flat high-grade dysplasia is endoscopic radiofrequency ablation therapy. The benefits of ablation for non-dysplastic BE and BE with low-grade dysplasia have yet to be validated. By understanding the intricacies of the development, screening, surveillance, and treatment of BE, new insights will be gained into the prevention and early detection of EAC that may ultimately lead to a reduction in morbidity and mortality in this patient population.

Chemoprevention in Barrett's esophagus: A pill a day?

Esophageal adenocarcinoma is increasing in incidence. The main risk factor is the premalignant condition of Barrett's esophagus. There is great interest in chemoprevention to prevent or slow malignant transformation. There are many agents proposed as playing a role in chemoprevention; however, none is licensed for this role as yet. Aspirin possesses many favorable qualities for chemoprevention and is the focus of the largest randomized control trial in this field.

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.

Advances in research on Barrett's esophagus

Over the past 20 years, the incidence of esophageal adenocarcinoma has increased dramatically. Barrett's esophagus is an acquired premalignant condition in which an abnormal columnar epithelium replaces the stratified squamous epithelium that normally lines the distal esophagus. Barrett's esophagus is often associated with long-standing gastroesophageal reflux disease. Gastric and/or bile contents may contribute to the development and malignant progression of Barrett's esophagus. At present, the uniform histopathologic definitions and diagnostic criteria for Barrett's esophagus, intestinal metaplasia at the gastroesophageal junction and cardiac metaplasia have not been established, and the correlation between Helicobactor pylori infection and gastroesophageal reflux disease is still a matter of ongoing debate. Recent studies have suggested that esophageal injury in Barrett's esophagus heals through the proliferation and differentiation of muti-potential progenitor cells derived from the bone marrow rather than from the injured organ itself. MicroRNAs (miRNAs) are potentially useful for development of biomarkers for evaluation of the prognosis of Barrett's esophagus and for early detection, chemoprevention, and treatment of esophageal cancer.

Endoluminal fundoplication (ELF) for GERD using EsophyX: a 12-month follow-up in a single-center experience

BACKGROUND

Several endoscopic antireflux therapies have been proposed to reduce the need for chronic medical therapy or laparoscopic fundoplication for gastroesophageal reflux disease (GERD). Aim of this study was to evaluate the short- and mid-term clinical results of endoluminal fundoplication (ELF) with EsophyX.

PATIENTS AND METHODS

From June 2006 to April 2008, 20 patients were enrolled in the study. All the ELFs were performed under general anesthesia.

RESULTS

The mean duration of the procedure was 63 min (range 38-105). A median of 14 fasteners was placed. There were no major intraoperative complications. Two patients developed early complications and were treated conservatively. Four patients underwent, within the first year post-ELF, a laparoscopic fundoplication because of persistence of symptoms. One patient was lost to follow-up between 6 and 12 months. Among the other 15 patients who completed 12 months follow-up, the GERD health-related quality of life score decreased from a median of 40 to a median of 10 (p < 0.05), and seven patients were still off proton pump inhibitor. An improvement in esophageal acid exposure was recorded in 16.6% of patients, while in 66.7%, it worsened.

CONCLUSIONS

ELF induced improvement of GERD symptoms and patients quality of life in a subgroup of patients with a reduced need for medication. However, it did not significantly change esophageal acid exposure in these patients. The need for revisional standard laparoscopic fundoplication was high.

In benign Barrett's epithelial cells, acid exposure generates reactive oxygen species that cause DNA double-strand breaks

Cells that sustain double-strand breaks (DSB) can develop genomic instability, which contributes to carcinogenesis, and agents that cause DSBs are considered potential carcinogens. We looked for evidence of acid-induced DNA damage, including DSBs, in benign Barrett's epithelial (BAR-T) cell lines in vitro and in patients with Barrett's esophagus in vivo. In BAR-T cells, we also explored the mechanisms underlying acid-induced DNA damage. We exposed BAR-T cells to acid in the presence of a fluorescent probe for reactive oxygen species (ROS) and in the presence or absence of disodium 4,4'-diisothiocyanatostilbene-2,2'-disulfonate (which prevents intracellular acidification) and N-acety-l-cysteine (a scavenger of ROS). DSBs were detected by Western blotting and immunofluorescence for histone H2AX phosphorylation and by CometAssay. During endoscopy in patients with Barrett's esophagus, we took biopsy specimens from the metaplastic mucosa before and after esophageal perfusion with 0.1 N HCl for 3 min and sought DSBs by Western blotting for histone H2AX phosphorylation. In BAR-T cells, acid exposure resulted in ROS production and caused a time-dependent increase in levels of phospho-H2AX that continued for at least 48 h. Pretreatment with disodium 4,4'-diisothiocyanatostilbene-2,2'-disulfonate or N-acety-l-cysteine prevented the acid-induced increase in phospho-H2AX levels. DSBs also were detected in biopsy specimens of Barrett's metaplasia following esophageal acid perfusion in all of 6 patients with Barrett's esophagus. Acid exposure causes DSBs in Barrett's epithelial cells through ROS produced as a consequence of intracellular acidification. These findings suggest that acid can be considered a carcinogen in Barrett's esophagus.

Clinical trial: intragastric acid control in patients who have Barrett's oesophagus--comparison of once- and twice-daily regimens of esomeprazole and lansoprazole

BACKGROUND

Gastric acid control is important for treatment of gastro-oesophageal reflux disease associated with Barrett's oesophagus. Substantial indirect evidence suggests that gastric acid control may have a chemopreventive role in Barrett's oesophagus.

AIM

To compare the pharmacodynamic efficacy of esomeprazole and lansoprazole at two dosages for intragastric pH control with Barrett's oesophagus.

METHODS

Patients with Barrett's oesophagus received open-label consecutive treatment (a 15-day period of once-daily dosing followed by a 10-day period of twice-daily dosing) with esomeprazole (40-mg capsules) and lansoprazole (30-mg capsules) in random order with no washouts. Twenty-four-hour intragastric pH was recorded on the last day of each dosing period. The primary end point was the percentage of time with intragastric pH > 4.0.

RESULTS

In the per-protocol once- (n = 46) and twice-daily (n = 41) analyses, the percentage of time with intragastric pH > 4.0 was significantly (P < 0.0001) longer after once- (67.1%) or twice-daily (81.2%) esomeprazole than after once- (50.8%) or twice-daily (64.3%) lansoprazole. The proportion of patients with intragastric pH > 4.0 for >12 h was significantly higher for esomeprazole than lansoprazole with once- (P = 0.004) and twice-daily (P = 0.016) dosing.

CONCLUSION

Esomeprazole 40 mg is significantly more effective than lansoprazole 30 mg in controlling intragastric pH with Barrett's oesophagus.

Endoscopic full-thickness plication for the treatment of GERD by application of multiple Plicator implants: a multicenter study (with video)

BACKGROUND

The full-thickness Plicator allows transmural suturing at the gastroesophageal (GE) junction to restructure the antireflux barrier. Studies of the Plicator procedure to date have been limited to placement of a single transmural suture to create the endoscopic gastroplication.

OBJECTIVE

The purpose of this study was to evaluate the safety and efficacy of placing multiple transmural sutures for the treatment of GERD.

DESIGN

Open-label, prospective, multicenter study.

SETTING

Four tertiary-referral centers.

PATIENTS

Subjects with symptomatic GERD who require daily maintenance proton pump inhibitor (PPI) therapy. Study exclusions were hiatal hernia >3 cm, grades III and IV esophagitis, Barrett's epithelium, and esophageal dysmotility.

INTERVENTIONS

Forty-one patients received two or more transmural sutures placed linearly in the anterior gastric cardia approximately 1 cm below the GE junction.

MAIN OUTCOME MEASUREMENTS

Six months after the procedure, median GERD-health-related quality of life (HRQL) improved 76% compared with off-medication baseline (6.0 vs 25.0, P < .001), with 75% of patients (32/40) achieving >50% improvement in their baseline GERD-HRQL score. Six months after the procedure, daily PPI therapy was eliminated in 70% of patients (28/40). Heartburn symptoms improved 80% compared with off-medication baseline (16.0 vs 84.0, P < .001). Median esophagitis grade improved 75% compared with baseline (0.0 vs 1.0, P = .005). Esophageal pH assessed as median distal esophageal-acid exposure (percentage time pH < 4.0) improved 38% compared with baseline (9.0 vs 11.0, P < .020; nominal P value for a single statistical test: significance removed upon the Bonferroni adjustment for multiple testing of data) and manometric outcomes were also improved compared with baseline (median lower esophageal sphincter resting pressure improved 25% [10.0 vs 6.0, P < .017; nominal P value for a single statistical test: significance removed upon the Bonferroni adjustment for multiple testing of data]) and median amplitude of contraction improved 11% (70.0 vs 62.0, P < .037; nominal P value for a single statistical test: significance removed upon the Bonferroni adjustment for multiple testing of data).

LIMITATIONS

Small sample size. No randomized comparison with a single implant group.

CONCLUSIONS

Endoscopic full-thickness plication with multiple serially placed implants was safe and effective in reducing GERD symptoms, medication use, esophageal-acid exposure, and esophagitis.

Physiological and molecular analysis of acid loading mechanisms in squamous and columnar-lined esophagus

Barrett's esophagus (BE) may be an adaptive cellular response to repeated acid exposure. The aims of this study were to compare intracellular acid loading in BE cells with normal squamous esophageal cells. Primary squamous and BE cells were obtained endoscopically and cultured for up to 24 h. Barrett's adenocarcinoma cell lines TE7 and OE-33 were compared with a normal esophageal (NE) cell line OE-21. Extracellular pH was lowered to 6.0 using HCl; specific ion exchangers were blocked pharmacologically and pH microfluorimetry was performed using 2'7'-bis(carboxyethyl)-5(6)-carboxyfluorescein. The effect of prolonged acid preincubations and repeated acid exposure on acid loading and recovery were examined. Acid loading was greater in primary BE than NE cells (DeltapHi -0.22 +/- 0.08 vs.-0.13 +/- 0.01) and maximal in the BE carcinoma cell line TE7 (DeltapHi -0.30 +/- 0.01). Whereas TE7 cells were able to recover fully from repeated acid exposure, OE-21 cells remained profoundly acidic. BE primary and transformed cells utilize DIDS inhibitable sodium-independent chloride/bicarbonate exchange as well as sodium/hydrogen ion exchange for acid loading. In contrast, SE only requires sodium-independent chloride/bicarbonate exchange for acidification. The degree of acid loading is greater in BE than NE cells and it occurs via dual ion exchangers similar to gastric mucosa. Only Barrett's epithelial cells can maintain a physiological pHi following prolonged and repeated reflux exposure, which may confer a teleological advantage.

Systematic review: the application of molecular pathogenesis to prevention and treatment of oesophageal adenocarcinoma

BACKGROUND

Oesophageal adenocarcinoma is an increasingly common cancer with a poor prognosis. It develops in a stepwise progression from Barrett's metaplasia to dysplasia, and then adenocarcinoma followed by metastasis.

AIM

To outline the key molecular changes in oesophageal adenocarcinoma and to summarize the chemopreventative and therapeutic strategies proposed.

METHODS

A literature search was performed to identify appropriate research papers in the field. Search terms included: Barrett's (o)esophagus, intestinal metaplasia, (o)esophageal adenocarcinoma, molecular changes, genetic changes, pathogenesis, chemoprevention, therapeutic strategies and treatment. The search was restricted to English language articles.

RESULTS

A large number of molecular changes have been identified in the progression from Barrett's oesophagus to oesophageal adenocarcinoma although there does not appear to be an obligate order of events. Potential chemoprevention strategies include acid suppression, anti-inflammatory agents and antioxidants. In established adenocarcinoma, targeted treatments under evaluation include receptor tyrosine kinase inhibitors of EGFR and cyclin-dependent kinase inhibitors, which may benefit a subgroup of patients.

CONCLUSIONS

Advances in molecular methodology have led to a greater understanding of the oesophageal adenocarcinoma pathways, which provides opportunities for chemoprevention and therapeutic strategies with a mechanistic basis. More work is required to assess both the safety and efficacy of these new treatments.

The evidence base of proton pump inhibitor chemopreventative agents in Barrett's esophagus--the good, the bad, and the flawed!

Gastric acid is believed to be an important etiological factor in the pathogenesis of Barrett's esophagus. Pulsatile acid exposure increases cell proliferation in ex vivo Barrrett's tissue and normalization of esophageal pH reverses this. Proton pump inhibitors (PPIs) are the mainstay of therapy in Barrett's esophagus, and have numerous beneficial effects including symptom control, reduction of inflammation, and promotion of the development of squamous islands. However, PPI therapy causes hypergastrinemia and has not prevented recent increase in the incidences of esophageal cancer. Additionally, evidence presented here by Feagins et al. suggests that acid exposure has a p53-mediated, antiproliferative effect on a nondysplastic Barrett's epithelial cell line, an effect that acid suppression might abrogate. These complex pH, inflammation, and growth factor biological interactions can be most reliably tested in large clinical trials with hard end points like cancer conversion or all causes of mortality. Combining the anti-inflammatory effects of acid suppression with aspirin, a nonsteroidal anti-inflammatory agent, is the subject of the AspECT clinical trial, and this may be the future of chemoprevention in Barrett's.

Acid has antiproliferative effects in nonneoplastic Barrett's epithelial cells

OBJECTIVES

For patients with Barrett's esophagus, physicians commonly prescribe antisecretory medications in dosages above those required to heal reflux esophagitis because acid has been shown to have proproliferative and antiapoptotic effects on Barrett's cancer cells and on Barrett's mucosal explants. For a number of reasons, these model systems may not be ideal for determining the effects of acid on benign Barrett's epithelial cells, however. We studied the effects of acid on proliferation and apoptosis in a nonneoplastic, telomerase-immortalized Barrett's epithelial cell line.

METHODS

Barrett's cells were treated with two 3-minute exposures to acidic media. Cell growth was determined using cell counts, proliferation was studied by flow cytometry, cell viability was determined by trypan blue staining, and apoptosis was assessed by TUNEL and Annexin V. The expression levels of p53 and p21 were determined by Western blotting. p53 siRNA was used to study the effect of p53 inhibition on total cell numbers after acid exposure.

RESULTS

Acid exposure significantly decreased total cell numbers at 24 h without affecting either cell viability or apoptosis. Acid exposure resulted in cell cycle prolongation that was associated with greater expression of p53, but not p21. The acid-induced decrease in total cell numbers was abolished by p53 RNAi.

CONCLUSIONS

Acid exposure has p53-mediated, antiproliferative effects in nonneoplastic Barrett's epithelial cells. These findings contradict the results of prior in vitro and ex vivo studies. We speculate that the prescription of antisecretory medications in dosages beyond those required to heal gastroesophageal reflux disease (GERD) symptoms and endoscopic signs could be detrimental. Controlled, prospective clinical trials are needed to determine the optimal level of acid suppression for patients with Barrett's esophagus.

Multilayered epithelium may be found in patients with Barrett's epithelium and dysplasia or adenocarcinoma

To determine if multilayered epithelium (MLE) is a useful prognostic indicator for a benign natural history of Barrett's epithelium, we evaluated endoscopic biopsies from patients with Barrett's epithelium without and with dysplasia and/or adenocarcinoma and from non-Barrett's controls for the presence of MLE. MLE was found in 6% of non-Barrett's controls, 30% of Barrett's patients with no dysplasia, and 14% of Barrett's patients with dysplasia and/or adenocarcinoma. MLE was significantly associated with shorter lengths of Barrett's epithelium in both Barrett's groups. Three of 5 photodynamic therapy patients were noted to develop MLE after therapy. MLE may be found in patients with dysplasia and/or adenocarcinoma and after photodynamic therapy; its presence is not useful as a prognostic indicator for a more benign course of Barrett's. This study confirms that MLE is significantly associated with shorter lengths of Barrett's epithelium.

Gastric and esophageal pH in patients with Barrett's esophagus treated with three esomeprazole dosages: a randomized, double-blind, crossover trial

BACKGROUND

It has been suggested that patients with Barrett's esophagus (BE) are unusually resistant to the antisecretory effects of proton pump inhibitors (PPIs).

OBJECTIVES

To compare intragastric and intraesophageal acidity in patients with BE receiving esomeprazole 40 mg three times daily (t.i.d.), esomeprazole 40 mg twice daily (b.i.d.), and esomeprazole 20 mg t.i.d.

METHODS

In this randomized, double-blind, three-way crossover study, patients with long-segment BE received each of the three esomeprazole dosages for 5 days separated by 10-14-day washout periods. Intragastric and intraesophageal pHs were measured for 24 h on day 5.

RESULTS

Among 31 patients with evaluable pH data, intragastric pH was >4.0 for 88.4%, 81.4%, and 80.4% of day 5 after treatment with esomeprazole 40 mg t.i.d., 40 mg b.i.d., and 20 mg t.i.d., respectively. Esomeprazole 40 mg t.i.d. was significantly more effective than the other dosages (p < 0.01). Intraesophageal pH was <4.0 for mean values of <5% of the monitoring period with all the three dosing regimens, but esophageal pH remained <4.0 for >5% of the time in 16%, 23%, and 19% of patients receiving esomeprazole 40 mg t.i.d., 40 mg b.i.d., and 20 mg t.i.d., respectively. All dosages were well tolerated.

CONCLUSIONS

All the three esomeprazole dosages significantly decreased intragastric acidity and reduced esophageal acid exposure to mean normal values in the total group of patients with BE. However, abnormal esophageal acid exposure continued in 16-23% of patients despite the significant decrease in gastric acidity. These results suggest that the apparent "PPI resistance" described in patients with BE may be caused by their profound reflux diathesis rather than by gastric resistance to the antisecretory effects of PPIs.

Review article: the long-term use of proton-pump inhibitors

More than 15 years after the launch of omeprazole in 1988, proton-pump inhibitors remain central to the management of acid-suppression disorders and are unchallenged with regard to their efficacy and popularity among doctors and patients. They are considered safe despite early concerns about the possibility of an association with cancer and gastric atrophy; current concerns about long-term proton-pump inhibitor therapy are centred mainly on a possible association with fundic gland polyps and between Helicobacter pylori and gastric atrophic changes. Long-term proton-pump inhibitor usage accounts for the majority of the total proton-pump inhibitor usage. Long-term usage is difficult to define and most patients take proton-pump inhibitors non-continuously. Data indicate that a substantial proportion of long-term users do not have a clear indication for their therapy and there is thus room for reduction or rationalization of treatment. Overall, on-demand therapy is more cost-effective than continuous therapy and should be considered wherever possible.

Epidemiologic risk factors for Barrett's esophagus and associated adenocarcinoma

The incidence of esophageal adenocarcinoma (AC) has increased dramatically in the Western world over the past 20 years and the majority of these cancers arise on the background of the preinvasive lesion Barrett's esophagus. The epidemiologic factors that contribute to an individual's susceptibility for Barrett's esophagus and associated cancer are likely to be multifactorial. However, the short time frame over which the incidence of adenocarcinoma has increased, and the increase across populations, provides a strong argument for environmental factors as etiologic agents, perhaps interacting with genetically determined characteristics that define personal susceptibility. In this review we discuss the epidemiologic evidence for the proposed demographic and environmental risk factors for the development of both Barrett's esophagus and AC. The current evidence suggests that significant risk factors include male sex, Caucasian race, and the presence of duodenogastroesophageal reflux disease. The susceptibility for reflux disease may in turn be influenced by factors such as obesity, the use of drugs that lower the lower-esophageal sphincter tone, and a protective effect of Helicobacter pylori colonization. There appears to be a weak association between smoking and AC. The role of dietary factors has not been studied adequately and deserves further attention. An understanding of the factors that predispose to the development and progression of Barrett's esophagus is crucial to the implementation of effective screening and prevention programs.

Genetics and prevention of oesophageal adenocarcinoma

Gastric cancer has been declining for more than half a century, whereas the incidence of oesophageal cancer is increasing rapidly. The histopathological subtype is also changing with a predominance of oesophageal adenocarcinoma compared with squamous carcinoma. The reasons for these epidemiological changes are not clear, although population-based data have implicated gastro-oesophageal reflux disease as a risk factor. In susceptible individuals reflux of duodeno-gastric contents can lead to the development of a columnar-lined oesophagus, commonly called Barrett's oesophagus. This can then progress to adenocarcinoma via a metaplasia-dysplasia-carcinoma sequence. At the current time, the mortality from oesophageal adenocarcinoma exceeds 80% at 5 years. Therefore, endoscopic surveillance programmes have been generally recommended for patients with Barrett's oesophagus in an attempt to detect early, curable lesions. Unfortunately these programmes are cumbersome and costly and have not yet been proved to reduce population mortality. In order to improve patient outcomes we need to be able to identify patients at high risk and to understand the triggers for disease progression. There is mounting evidence that there is an underlying genetic susceptibility to Barrett's oesophagus and oesophageal adenocarcinoma. However, this is likely to be as a result of multiple low penetrance susceptibility genes which have yet to be identified. Once patients are identified as having Barrett's oesophagus their chance for developing adenocarcinoma is in the order of 0.5%-1% per year. The histological assessment of dysplasia as a predictor of cancer development is highly subjective. Therefore multiple, specific somatic mutations in the tissue have been investigated as potential biomarkers. The most promising markers to date are the presence of aneuploidy, loss of heterozygosity of p53 and cyclin D1 overexpression. However, a study of evolutionary relationships suggest that mutations occur in no obligate order. Combinatorial approaches are therefore being advocated which include genomic profiling or the use of a panel of molecular markers in order to define the common molecular signatures that can then be used to predict malignant progression. An alternative approach would be to use markers for the final common pathway following genetic instability, which is the loss of proliferative control. We have demonstrated an increase in the expression of a novel proliferation marker, Mcm2, which occurs during the malignant progression of Barrett's oesophagus. These Mcm2-expressing cells are detectable on the surface, and hence a cytological approach may be applicable. In view of the role of reflux components in the pathogenesis of Barrett's oesophagus the effect of acid and bile on the cell phenotype have been studied. These studies have demonstrated that pulsatile acid and bile exposure induce cell proliferation. The mechanism for the hyperproliferative response appears to involve p38 mitogen activated protein kinase (MAPK) pathways as well as protein kinase C (PKC) and cyclo-oxygenases. A clinical implication of the laboratory studies is that suppression of acid and bile may need to be profound in order to suppress cell proliferation and, by inference, ultimately prevent the development of dysplasia. There is some support for this concept from short-term clinical studies, and a large randomised chemoprevention trial is being instigated which will evaluate the effect of proton pump inhibitors with or without aspirin. Given the epidemic increase in oesophageal adenocarcinoma and the dismal 5-year mortality rate, a radical approach is necessary to prevent cancer development in individuals with pre-malignant lesions.

Review article: Barrett's oesophagus and associated adenocarcinoma--a UK perspective

In the UK and across the Western world there has been a rapid increase in oesophageal adenocarcinoma, such that this cancer is now more common than squamous cell carcinoma. The 5-year mortality from oesophageal adenocarcinoma is >80% and therefore there has been increasing interest in the pre-malignant condition Barrett's oesophagus. Barrett's oesophagus is defined by a visible columnar-lined segment with histopathological evidence of a glandular epithelium, which typically contains intestinal metaplasia. Once Barrett's oesophagus is diagnosed, most centres in the UK offer endoscopic surveillance with the aim to detect early, curable lesions. Surveillance in its current form is cumbersome and expensive, and new endoscopic and molecular developments are hoped to improve the yield of such procedures. The current treatments are symptomatic control of reflux symptoms, with more definitive treatments usually reserved for patients with at least high-grade dysplasia. There is interest in chemoprevention strategies, including proton-pump inhibitors, cyclo-oxygenase-2 inhibitors and aspirin, but to date none of these have proven effective. Treatment options for high-grade dysplasia include surgery, endoscopic mucosal resection (in the context of a visible lesion) and photodynamic therapy. Comparative studies between various geographical regions, as the predominant histopathological subtypes of oesophageal cancer change, may give us some clues about the pathogenesis of Barrett's adenocarcinoma.

Review article: the pharmacodynamics and pharmacokinetics of proton pump inhibitors--overview and clinical implications

During the past two decades, enormous changes occurred in the management of gastric acid-related diseases. First, the histamine2-receptor antagonists were introduced, offering patients the first single-agent therapy that effectively reduced gastric acid secretion. Proton pump inhibitors became widely available in the early 1990s, and they generally appeared to be superior to the histamine2-receptor antagonists in acid-suppressing activity, symptom control and healing. Most physicians now use proton pump inhibitors as first-line treatment for many patients with acid-peptic disorders, including erosive gastro-oesophageal reflux disease (GERD), nonerosive reflux disease (NERD) and duodenal and gastric ulcers. Although proton pump inhibitors are often thought to be interchangeable, some differences have emerged in their pharmacological properties, which may be reflected in some aspects of clinical efficacy. Such differences include potency, speed of onset and duration of pH 'holding times'. Helicobacter pylori has now been recognized as an important factor in the pathogenesis of acid-peptic disorders. It is clear that H. pylori eradication can dramatically reduce the chronicity of gastric and duodenal ulcers, and accepted therapeutic regimens for H. pylori eradication now include proton pump inhibitors and two or more antibiotics. Although all accepted proton pump inhibitor-based 'triple therapies' are roughly equivalent in efficacy, there is now a shortened regimen available that will potentially enhance compliance and decrease cost. This review examines the relative advantages of proton pump inhibitors vs. histamine2-receptor antagonists in the context of acid suppression and in various gastric acid-related diseases. A brief overview presents the pharmacodynamics and pharmacokinetics of the proton pump inhibitors with particular attention paid to rabeprazole, one of the newer drugs in its class.

Detection of oxidative DNA damage in oesophageal biopsies of patients with reflux symptoms and normal pH monitoring

BACKGROUND

Gastro-oesophageal reflux has been shown to induce oxidative DNA damage.

AIM

To determine whether oxidative DNA damage, detected in oesophageal biopsies by simple immunohistochemical staining, correlates with gastro-oesophageal reflux disease as determined by pH monitoring.

METHODS

The study included 47 patients with reflux symptoms who had oesophageal biopsy and 24-h pH monitoring studies performed within 3 months of each other with no variation in treatment in the time between the two procedures. Sections of formalin-fixed and paraffin-embedded oesophageal biopsies were stained for 8-hydroxy-2'-deoxyguanosine using the standard immunoperoxidase method. Positive nuclear immunoreactivity was considered to indicate oxidative DNA damage.

RESULTS

Seven (33%) of the 21 cases with normal 24-h pH monitoring results were negative for oxidative DNA damage, compared with only two (8%) of the 26 cases with abnormal 24-h pH results (P=0.058, two-sided Fisher's exact test). Five of the patients with normal 24-h pH results had oesophageal biopsies performed within 24 h of the monitoring procedure and, of these, four (80%) were positive for oxidative DNA damage, including a case in which both biopsy and 24-h pH monitoring were performed on the same day whilst the patient was on proton pump inhibitor therapy. All cases with normal 24-h pH results and positive oxidative DNA damage showed features of reflux on routine morphological evaluation.

CONCLUSIONS

Oxidative DNA damage can occur in the absence of acid reflux and despite adequate antisecretory therapy. This may indicate that other agents, such as bile, can induce oxidative DNA damage in an acid-suppressed environment. The significant discordance between oxidative DNA damage and 24-h pH results makes the determination of oxidative DNA damage a poor surrogate marker for 24-h pH monitoring.

Pharmacotherapy for chronic gastro-oesophageal reflux disease and Barrett's oesophagus

Over the last two decades there have been major advances in the medical treatment of gastro-oesophageal reflux disease (GORD) and Barrett's oesophagus. Motility agents, H(2)-receptor antagonists and proton-pump inhibitors (PPI) have all been evaluated in short- and long-term studies. Symptomatic response needs to be differentiated from healing of oesophagitis and maintenance of remission. Clinical trials have convincingly demonstrated the superiority of PPIs to motility agents and H(2)-receptor antagonists for all clinical aspects of GORD. Barrett's oesophagus requires lifelong acid suppression. Treatment with standard doses of PPIs is often insufficient and higher doses are frequently required. Medical treatment does not appear to result in clinically significant regression of Barrett's oesophagus.