Acid suppression therapy may not alter malignant progression in Barrett's metaplasia showing p53 protein accumulation

Hydroalcoholic extract from Baccharis dracunculifolia recovers the gastric ulcerated tissue, and p-coumaric acid is a pivotal bioactive compound to this action

Baccharis dracunculifolia is a medicinal plant native to southeastern Brazil and is the main botanical source used by bees (Apis mellifera) in the manufacture of green propolis and display similar gastroprotective action and chemical profile. This article reports the healing gastric ulcer activity of the hydroethanolic extract of B. dracunculifolia (HEBD) in an acetic acid-induced ulcer model. In addition to the extract, the isolated compounds ferulic acid, p-coumaric acid, caffeic acid, baccharin, and aromadendrin-4'-O-methyl ether were also assayed. HEBD at a dose of 300 mg/kg reduced the ulcerated area by 49.4% after treatment for 7 days, twice a day. Histological analyses revealed that the margins and base of the ulcer obtained significant regeneration, and periodic acid Schiff base staining showed a 78.2% increase in the mucin levels. The action on the enzymatic antioxidant system demonstrated an increased activity of superoxide dismutase and glutathione-S-transferase, in addition to raising glutathione reduced levels and myeloperoxidase activity. HEBD did not show cytotoxicity in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenylterazole bromine test. In vitro, HEBD inhibited the H⁺ /K⁺ -ATPase enzyme and showed antioxidant activity in the 2,2 diphenyl-1-picryllydrazyl test. Regarding the isolated compounds, oral administration of p-coumaric acid (15 mg/kg) reduced the ulcerated area by 66.2%. The results suggest that HEBD recovers the gastric ulcerated tissue, raising mucus and antioxidant enzyme levels, and reducing the H⁺ /K⁺ -ATPase activity. In addition, the findings confirm that p-coumaric acid is a pivotal bioactive compound on the gastric healing effects elicited by HEBD. © 2019 BioFactors, 45(3):479-489, 2019.

Lack of incremental effect of histamine receptor antagonists over proton pump inhibitors on the risk of neoplastic progression in patients with Barrett's esophagus: a cohort study

OBJECTIVE

Long-term acid suppression reduces the risk of progression to esophageal adenocarcinoma (EAC) in patients with Barrett's esophagus (BE). Given recent reports about the harmful effects of using chronic proton pump inhibitors (PPI) there is renewed interest in alternative methods of acid suppression. Hence, we studied the effect of H2 receptor antagonists (H₂ RA) on the risk of progression to neoplasia in our BE cohort.

METHODS

This is a retrospective analysis of prospectively collected data of patients in our BE registry from 2002 to 2015. Patients' characteristics, endoscopic findings, such as the length of BE, hiatal hernia size and histological findings and patients' use of medications such as PPI, aspirin, H₂ RA, metformin and antihyperlipidemic agents were studied.

RESULTS

The cohort consisted of 1466 patients with a mean age of 61 ± 13 years. The patients had a predominance of male sex (76.7% [1118/1457]) and Caucasian race (96.6% [1209/1252]). After excluding prevalent high-grade dysplasia (HGD) or EAC, 1025 patients had a median follow up of 43.6 months during which 57 patients progressed to HGD or EAC. PPI use (56% in progressors vs 69% in non-progressors; P = 0.007) but not H₂ RA use (12% progressors vs 19% in non-progressors P = 0.162) was associated with lower risk of neoplastic progression. On multivariate analysis, there was no synergistic effect of addition of H₂ RA to PPI on risk of neoplastic progression to HGD or EAC (relative risk 0.33; confidence intervals 0.05-2.29, P = 0.262).

CONCLUSION

H₂ RA do not seem to have a chemopreventive role in patients with BE.

BOB CAT: A Large-Scale Review and Delphi Consensus for Management of Barrett's Esophagus With No Dysplasia, Indefinite for, or Low-Grade Dysplasia

OBJECTIVES

Barrett's esophagus (BE) is a common premalignant lesion for which surveillance is recommended. This strategy is limited by considerable variations in clinical practice. We conducted an international, multidisciplinary, systematic search and evidence-based review of BE and provided consensus recommendations for clinical use in patients with nondysplastic, indefinite, and low-grade dysplasia (LGD).

METHODS

We defined the scope, proposed statements, and searched electronic databases, yielding 20,558 publications that were screened, selected online, and formed the evidence base. We used a Delphi consensus process, with an 80% agreement threshold, using GRADE (Grading of Recommendations Assessment, Development and Evaluation) to categorize the quality of evidence and strength of recommendations.

RESULTS

In total, 80% of respondents agreed with 55 of 127 statements in the final voting rounds. Population endoscopic screening is not recommended and screening should target only very high-risk cases of males aged over 60 years with chronic uncontrolled reflux. A new international definition of BE was agreed upon. For any degree of dysplasia, at least two specialist gastrointestinal (GI) pathologists are required. Risk factors for cancer include male gender, length of BE, and central obesity. Endoscopic resection should be used for visible, nodular areas. Surveillance is not recommended for <5 years of life expectancy. Management strategies for indefinite dysplasia (IND) and LGD were identified, including a de-escalation strategy for lower-risk patients and escalation to intervention with follow-up for higher-risk patients.

CONCLUSIONS

In this uniquely large consensus process in gastroenterology, we made key clinical recommendations for the escalation/de-escalation of BE in clinical practice. We made strong recommendations for the prioritization of future research.

Evidence for DNA damage checkpoint activation in barrett esophagus

Barrett esophagus is an epithelial metaplasia that predisposes to adenocarcinoma. Better markers of cancer risk are urgently needed to identify those patients who are likely to benefit most from emerging methods of endoscopic ablation. Disease progression is associated with genomic DNA changes (segmental gains, losses, or loss of heterozygosity). Although these changes are not easily assayed directly, we hypothesized that the underlying DNA damage should activate a DNA damage response (DDR), detectable by immunohistochemical (IHC) assays of checkpoint proteins and the resulting replicative phase cell cycle delays. Surgical specimens and endoscopic biopsies (N = 28) were subjected to IHC for the cell cycle markers cyclin A and phosphorylated histone H3 (P-H3), the DDR markers gammaH2AX and phosphorylated ATM/ATR substrates (P-ATM/ATRsub), and the DNA damage-responsive tumor suppressors p16 and p53. Correlations were made with histologic diagnoses. The fractions of cells that stained for cyclin A, P-H3, and gammaH2AX increased in parallel in dysplastic tissue, consistent with checkpoint-mediated cell cycle delays. Foci of nuclear gammaH2AX and P-ATM/ATRsub were demonstrated by standard and confocal immunofluorescence. Staining for p16 was more prevalent in early-stage disease with lower staining for gammaH2AX and P-H3. Staining for p53 was moderately increased in some early-stage disease and strongly increased in some advanced disease, consistent with checkpoint-mediated induction and mutational inactivation of p53, respectively. We suggest that IHC for DDR-associated markers may help stratify risk of disease progression in Barrett.

Predictors of progression in Barrett's esophagus: current knowledge and future directions

Barrett's esophagus (BE) is the strongest risk factor for esophageal adenocarcinoma (EAC), a malignancy with persistently poor long-term outcomes. EAC is thought to develop through progression of metaplasia to dysplasia to invasive carcinoma. Identification of factors predicting progression to EAC would help in focusing surveillance, chemoprevention, or ablation for those deemed to be at highest risk of progression. We performed a comprehensive review of the literature and summarized current evidence on risk factors for progression in subjects with known BE. Clinical and demographic factors (age, male gender, length of BE segment) are associated with modestly increased odds of progression to EAC in some studies. Biomarkers such as aneuploidy and p53 loss of heterozygosity have been associated with increased risk of progression to high-grade dysplasia and/or EAC in single-center prospective cohort studies. Promising newer techniques and markers have been recently reported with the potential to help risk stratify BE subjects. Development of a comprehensive BE risk progression score comprised of both clinical and biomarker variables should be the ultimate goal and can be achieved by multicenter prospective collaborative efforts. Although it would be challenging, creation of such a score has the potential to improve outcomes and make the management of patients with BE more cost-effective.

The role of Cdx2 in Barrett's metaplasia

Metaplasia (or transdifferentiation) is defined as the transformation of one tissue type to another. Clues to the molecular mechanisms that control the development of metaplasia are implied from knowledge of the transcription factors that specify tissue identity during normal embryonic development. Barrett's metaplasia describes the development of a columnar/intestinal phenotype in the squamous oesophageal epithelium and is the major risk factor for oesophageal adenocarcinoma. This particular type of cancer has a rapidly rising incidence and a dismal prognosis. The homoeotic transcription factor Cdx2 (Caudal-type homeobox 2) has been implicated as a master switch gene for intestine and therefore for Barrett's metaplasia. Normally, Cdx2 expression is restricted to the epithelium of the small and large intestine. Loss of Cdx2 function, or conditional deletion in the intestine, results in replacement of intestinal cells with a stratified squamous phenotype. In addition, Cdx2 is sufficient to provoke intestinal metaplasia in the stomach. In the present paper, we review the evidence for the role of Cdx2 in the development of Barrett's metaplasia.

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.

Cdx genes, inflammation and the pathogenesis of Barrett's metaplasia

Metaplasia is the conversion of one cell or tissue type to another and can predispose patients to neoplasia. Perhaps one of the best-known examples of metaplasia is Barrett's metaplasia (BM), a pathological condition in which the distal oesophageal epithelium switches from stratified squamous to intestinal-type columnar epithelium. BM predisposes to oesophageal adenocarcinoma and is the consequence of long-term acid bile reflux. The incidence of BM and oesophageal adenocarcinoma has risen dramatically in recent years. A key event in the pathogenesis of BM is the induction of oesophageal CDX2 expression. Importantly, recent data reveal the molecular mechanisms that link inflammation in the development of Barrett's metaplasia, CDX2 and the progression to cancer. This review highlights the relationship between inflammation, metaplasia and carcinogenesis.

Sorafenib inhibits MAPK-mediated proliferation in a Barrett's esophageal adenocarcinoma cell line

Esophageal adenocarcinoma continues to rise in incidence. Despite recognition of Barrett's metaplasia as the histological precursor, prognosis remains poor. The mitogen-activated protein kinases (MAPK) pathway is activated in Barrett's-associated dysplasia and adenocarcinoma and this activation is, in part, due to acid and bile acid reflux. We investigated the effects of sorafenib, an orally active Raf-inhibitor, on acid and bile acid-stimulated growth and signaling in SEG-1 cells, derived from a Barrett's esophageal cancer. SEG-1 cells were pretreated with sorafenib or vehicle and subsequently stimulated with acid or bile acid. MAPK signals, including phospho-ERK and phospho-p38, as well as cyclin D1 expression were assessed by Western blotting. Cell proliferation was measured by WST-1 colorimetric assay. Acid (pH 3.0-4.0) and bile acid (taurocholate 50-100 micromol/L) activated ERK and p38. Acid and bile acid exposure also increased levels of cyclin D1, a G1 to S cell cycle regulator. Furthermore, acid and taurocholate exposure increased cell proliferation. Sorafenib abrogated MAPK activation and cyclin D1 up-regulation and significantly inhibited cell growth. In summary, sorafenib inhibits acid or bile acid-stimulated Barrett's esophageal cancer cell proliferation by a mechanism involving the MAPK pathway. Our results suggest that sorafenib might be useful in the management of Barrett's-associated dysplasia and adenocarcinoma. These findings provide a foundation for in vivo studies to assess the efficacy of sorafenib in Barrett's-related neoplasia.

The expression of 8-hydroxydeoxyguanosine in oesophageal tissues and tumours

PURPOSE

The most common marker of oxidative DNA damage is 8-hydroxydeoxyguanosine (8-OHdG), which is linked with several malignancies. In the present study we investigated whether DNA damage linked to oxidative stress (as 8-OHdG) is present in Barrett's mucosa with or without associated adenocarcinoma or high-grade dysplasia and in normal controls' squamous mucosa.

EXPERIMENTAL DESIGN

We measured 8-OHdG in 51 patients (13 Barrett's metaplasia, six Barrett's oesophagus with high-grade dysplasia, 18 adenocarcinoma of the distal oesophagus/oesophagogastric junction and 14 normal controls). The amount of DNA damage was determined by high-performance liquid chromatography in oesophagus samples obtained either from endoscopy or as samples from surgery. The median 8-OHdG concentration was expressed as the ratio of 8-OHdG per 10(5) deoxyguanosine.

RESULTS

Analysis revealed that 8-OHdG was present in both Barrett's metaplasia with and without dysplasia as well as in adenocarcinoma of the oesophagus/oesophagogastric junction. Although the study group was small the amount of 8-OHdG was significantly increased in the distal oesophagus both in Barrett's epithelium 1.26 (0.08-29.47) and in high-grade dysplasia 1.35 (1.04-1.65) as well as in adenocarcinoma of oesophagus/oesophagogastric junction 1.08 (0.59-1.94) compared to controls 0.06 (0-4.08) (p=0.002, p=0.012, p=0.001, respectively). Barrett's patients had no significant difference in 8-OHdG levels between their distal and proximal oesophageal samples.

CONCLUSIONS

Our results show the presence of oxidative DNA damage in the distal oesophagus of patients with Barrett's oesophagus and adenocarcinoma of the oesophagus/oesophagogastric junction. This may have a connection to carcinogenesis in Barrett's oesophagus.

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.

Clinical use of p53 in Barrett's esophagus

Barrett's esophagus is an established precursor to esophageal adenocarcinoma. Whereas most patients with Barrett's esophagus do not progress to adenocarcinoma, patients with progression have a poor prognosis. Current management strategies use frequent endoscopic surveillance and multiple nontargeted biopsies. This approach, however, may miss dysplastic areas. Furthermore, given the relatively high prevalence of Barrett's esophagus but low incidence of progression, this invasive and expensive approach has not been shown to be cost-effective. Thus, there is intense interest in using biomarkers to identify patients at increased risk of progressing to adenocarcinoma. This has included examination of mutations in the tumor suppressor gene, p53. In this report, we discuss the biology of p53 and the incidence of p53 mutations in Barrett's esophagus and review relevant studies regarding the ability of p53 to predict neoplastic progression. Additionally, we report our results of the expression of p53 by immunohistochemistry in a group of 18 patients that have undergone endoscopic esophageal mucosal resection for dysplasia. Although the presence of a p53 mutation increases the risk of neoplastic progression, the absence of this mutation does not abrogate the risk. Continuing efforts, therefore, are needed to define and prospectively validate a panel of biomarkers to risk-stratify patients with Barrett's esophagus. Determination of p53 mutational status may ultimately be a component of such a panel.

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.

Antireflux surgery and esophageal mucosal DNA damage

Gastroesophageal reflux disease (GERD) is characterized by reflux of gastroduodenal contents, esophagitis and oxidative tissue damage in the distal esophagus. It may ultimately lead to the development of a pre-malignant Barrett's esophagus and subsequently to carcinoma. Antireflux surgery is an effective therapeutic tool to relieve GERD symptoms and to normalize the reflux to the distal esophagus. However, antireflux surgery may be insufficient to restore oxidative insult, which can promote DNA adduct formation and subsequent initiation of carcinogenesis. Controversy exists whether antireflux surgery can reverse the development of carcinoma in the mucosa. We aimed to test the effect of antireflux surgery on DNA adduct formation in the esophagus. Patients (n = 19) with objectively confirmed GERD underwent antireflux surgery and were followed up for 6 months after which a symptom evaluation, control endoscopy, biopsy and pH-measurements were performed. The amounts of DNA adducts in the proximal and distal mucosa of the esophagus were measured using the 32-P-postlabelling method. After the surgery, esophageal acid exposure was normalized in all the patients and symptoms were relieved in all but one patient. Endoscopic examinations showed that erosive esophagitis had healed in all the cases 6 months after the surgery. Barrett's esophagus was found in six cases in preoperative biopsies. The amount of DNA adducts in the distal esophagus was higher than in the proximal esophagus both pre- and postoperatively. Antireflux surgery did not change this pattern and was thus not capable of reducing DNA adduct formation. The level of DNA damage was similar in the patients having Barrett's esophagus compared to the rest of the patients. Antireflux surgery is insufficient to normalize DNA damage due to GERD. Our observations suggest that antireflux surgery is perhaps not effective in the prevention of carcinogenesis because of the persisting DNA damage.

Lack of predictors of normalization of oesophageal acid exposure in Barrett's oesophagus

BACKGROUND

Barrett's oesophagus patients may continue to have abnormal oesophageal acid exposure on proton pump inhibitor therapy. The effect of factors such as Barrett's oesophagus length, hiatal hernia size and Helicobacter pylori infection on intra-oesophageal pH in Barrett's oesophagus patients has not been adequately studied.

AIM

To evaluate oesophageal acid exposure in a large Barrett's oesophagus population on b.d. proton pump inhibitor therapy and determine clinical factors predicting normalization of intra-oesophageal pH on therapy.

METHODS

Barrett's oesophagus patients were studied using 24 h pH monitoring to evaluate intra-oesophageal acid suppression on b.d. dosing of rabeprazole.

RESULTS

Forty-six Barrett's oesophagus patients completed the study. Median total percentage time pH < 4 was 1.05% (range: 0-29.9%) in the entire group and respective values for upright and supine percentage time pH < 4 were 1.15% and 0%. However, 34 of the Barrett's oesophagus patients (73.9%) had a normal pH study (median total percentage time pH < 4: 0.2%) and 12 patients (26.1%) had an abnormal result (median total percentage time pH < 4: 9.3%). There were no significant differences between patients with a normal and abnormal 24 h pH result with respect to age, Barrett's oesophagus length, hiatal hernia size and presence of H. pylori infection.

CONCLUSIONS

Approximately 25% of Barrett's oesophagus patients continue to have abnormal total intra-oesophageal pH profiles despite b.d. proton pump inhibitor therapy. Factors such as age, Barrett's oesophagus length and hiatal hernia size cannot be used to predict persistent abnormal intra-oesophageal pH on proton pump inhibitor.

What is the role of cytokeratins in Barrett/cardia differentiation?

The importance of distinguishing between Barrett metaplasia and intestinal metaplasia of the gastric cardia is now accepted, and the management of each entity is quite different. Patients with Barrett metaplasia are enrolled in surveillance programs, consisting of periodic endoscopy and biopsy, because of the known risk of developing adenocarcinoma of the esophagus. Patients with intestinal metaplasia of the gastric cardia, however, are not currently enrolled in such programs, because this condition carries a low risk of developing adenocarcinoma of the gastric cardia. The distinction between both conditions by morphologic examination of routine histologic sections of endoscopic biopsies is extremely difficult if at all possible. A group of investigators proposed the use of immunostains for cytokeratin (CK) 7 and CK20 to overcome such difficulty. They concluded that the Barrett CK7/CK20 pattern was a highly sensitive and specific marker for Barrett metaplasia. Their observations, however, were not confirmed by other investigators. However, because it may be associated with premalignant lesions elsewhere in the gastric mucosa, we propose that intestinal metaplasia of the gastric cardia may have the same clinical implication as Barrett metaplasia.

p53 and the malignant progression of Barrett's esophagus

Barrett's esophagus (BE) is a metaplastic disorder in which specialized columnar epithelium replaces healthy squamous epithelium (intestinal metaplasia). Even though its pathophysiology and the steps of its neoplastic progression are not completely understood, BE can be considered as a complication of gastroesophageal reflux disease (GERD). Given that esophageal adenocarcinoma, which is continually increasing in the Western world, still has a poor prognosis and suffers from late diagnosis, and because BE is a precancerous lesion, there is a strong need for good molecular markers of malignant progression in Barrett's metaplasia (BM). The aim of this review is to examine the published data regarding the role that assessment of p53 may play in the management of BE, trying to understand if it may be a useful marker to early diagnose BE malignant transformation.

Proton pump inhibitors are associated with reduced incidence of dysplasia in Barrett's esophagus

BACKGROUND AND AIMS

Esophageal acid exposure is important in the pathogenesis of Barrett's esophagus (BE), and possibly in the progression of BE to dysplasia and carcinoma. The aim of this study is to compare the development of dysplasia in BE patients treated with or without proton pump inhibitor (PPI) or histamine 2-receptor antagonist (H2RA).

METHODS

We analyzed prospectively collected data by a single endoscopist on patients with BE in a VA (Veterans Affairs) setting over a 20-yr time period (1981-2000). A pathologist used standard criteria to diagnose BE/dysplasia. Pharmacy information after 1994 was retrieved from a computerized database, and from research files for the period before that. The receipt and the duration of H2RA and/or PPI use was compared between those with and without dysplasia. The incidence of dysplasia was examined in a Kaplan-Meier survival analysis stratified by PPI treatment status, and the risk of dysplasia was examined in a Cox multiple regression analysis controlling for demographic features, length of BE, and the year of BE diagnosis.

RESULTS

We analyzed data for 236 unique veteran patients with a mean age at BE diagnosis of 61.5 yr, 86% Caucasian, and 98% male. During 1,170 patient-yr of follow-up, 56 patients developed dysplasia giving an annual incidence rate of 4.7%. Of those, 14 had high-grade dysplasia. The cumulative incidence of dysplasia was significantly lower among patients who received PPI after BE diagnosis than in those who received no therapy or H2RA; log rank test (p < 0.001). Furthermore, among those on PPIs, a longer duration of use was associated with less frequent occurrence of dysplasia. In multivariate analysis, the use of PPI after BE diagnosis was independently associated with reduced risk of dysplasia, hazards ratio: 0.25 (95% CI 0.13-0.47), p < 0.0001. Longer segments of BE and Caucasian race were other independent risk factors for developing dysplasia. In general, similar findings were observed when only cases with high-grade dysplasia were analyzed.

CONCLUSIONS

These results indicate that PPI therapy is associated with a significant reduction in the risk of developing dysplasia in patients with BE. However, more studies are required to confirm this finding.

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.

Reflux, Barrett's oesophagus and adenocarcinoma: burning questions

The incidence of oesophageal adenocarcinoma is increasing rapidly in Western populations. Gastro-oesophageal reflux disease is a strong risk factor for both this tumour and the pre-cancerous lesion Barrett's oesophagus, but the underlying disease mechanisms remain unclear. Developing a better understanding of the aetiology and pathogenesis of Barrett's oesophagus, including the induction of DNA damage and genetic alterations, might provide opportunities for improved management of individuals with this disease. This could include a better rationale for screening and surveillance programmes, as well as targeted intervention strategies.

Barrett esophagus

PURPOSE

The importance of an in-depth understanding about Barrett esophagus is ultimately to decrease the mortality and morbidity from esophageal adenocarcinoma cancer by early detection of metaplasia and dysplasia and appropriate therapy. This review summarizes several publications in the past year related to the epidemiology, pathogenesis, screening and surveillance, new methods for detection of metaplasia/dysplasia, and advances in the treatment of Barrett esophagus.

RECENT FINDINGS

Patients with Barrett esophagus are characterized by the presence of risk factors usually indicative of severe types of gastroesophageal reflux disease. Recent insights into epidemiology and pathogenesis have shown that the risk of high-grade dysplasia and adenocarcinoma may be related to the increasing length of Barrett esophagus, size of hiatus hernia, and severity of acid reflux. The role of smoking and alcohol consumption remains controversial. Increasing the number of biopsies by repeat standard endoscopy can enhance the yield of intestinal metaplasia in patients with suspected short-segment Barrett esophagus. Costs of surveillance using standard endoscopy and random biopsies would be very high and using special techniques to target specific areas could ultimately help in cost reduction. Emerging data on new techniques and technology such as vital staining with methylene blue and protoporphyrin fluorescence can increase the yield of metaplasia and dysplasia. Biomarkers studies have revealed that p53 mutation by the loss of heterozygosity can help detect patients with low and high risk for cancer progression. Studies thus far have been unclear whether acid suppression alone can impact the malignant progression in Barrett esophagus patients. Inhibition of cyclooxygenase by aspirin or nonsteroidal anti-inflammatory drugs may be a promising chemoprevention strategy against dysplasia and esophageal adenocarcinoma development as shown in some recent studies. Nonsurgical treatment by photodynamic therapy or mucosal resection may be a less invasive and organ-sparing option for some patients with high-grade dysplasia and early adenocarcinoma.

SUMMARY

In the past year we have made major strides in our knowledge of this premalignant lesion. Recent studies have shed light in a better understanding of the epidemiology of Barrett esophagus, including clinical and endoscopic factors associated with high-grade dysplasia or esophageal adenocarcinoma and various biomarkers that would identify patient subsets with low and high risk for cancer progression. This will eventually have significant implications on the screening, surveillance, and treatment of the disease. Advanced endoscopic therapies including mucosectomy or photodynamic therapy may be emerging options in patients with intraepithelial neoplasia.

Biomarkers in Barrett's esophagus

This article provides a framework for clinicians who are attempting the difficult task of interpreting the Barrett's biomarker literature with the goal of improving care for their patients. Although many articles. including more that 60 proposed biomarkers, have been published on this subject, only a few describe phase 3 and 4 studies that are of interest to the clinical gastroenterologist (Table 1). For year, dysplasia grade has been the sole means of risk stratification for patients with BE, and it likely will continue to be used in the foreseeable future. The current authors believe that dysplasia classification can be valuable using the team management approach and quality controls described previously. Significant problems, however, have emerged in phase 2 through 4 studies of dysplasia that make it imperative for the Barrett's field to incorporate additional biomarkers as they are validated. These problems include poor reproducibility of dysplasia interpretations, poor predictive value for negative, indefinite, and low-grade dysplasia, and inconsistent results for HGD in different centers, all of which makes it virtually impossible to develop national guidelines for surveillance. Some studies have even suggested that endoscopic biopsy surveillance using dysplasia may not be worthwhile. Currently, flow cytometric tetraploidy and aneuploidy have progressed furthest in biomarker validation (see Table 1). With proper handling, endoscopic biopsy specimens can be shipped to reference laboratories that have the instruments, computer analytic methods, and expertise to reproducibly detect tetraploidy and aneuploidy. The results of phase 4 studies indicate that flow cytometry appears to be useful in detecting a subset of patients who do not have HGD and yet have an increased risk of progression to cancer that cannot be identified by dysplasia grade. For many reasons, the authors anticipate that the number of validated biomarkers will increase substantially in the future. Biopsy repositories are now readily available for phase 3 studies that can evaluate and compare biomarkers. There are initiatives for multi-institutional Barrett's Centers of Excellence that could provide rapid progress in biomarker evaluation. In addition to new candidate biomarkers, the human genome project has provided high-throughput methodologies and methods for computer analysis of data, which can provide the volume and quality control required for clinically useful biomarkers. Currently, 17p (p53) LOH has progressed the furthest among molecular biomarkers. The authors do not recommend its routine clinical use at the present time, however. Finally, it is likely that clinicians will want to follow the results of clinical treatment-response studies and epidemiologic studies that evaluate relationship between clinical interventions or environmental risk and protective factors and surrogate endpoints, especially if the endpoints are progessing well along the phases of biomarker validation. These studies are likely to be of clinical interest because they may becoming the basis for randomized clinical trials to prevent cancer in BE.