A Method for Increasing the Robustness of Stable Feature Selection for Biomarker Discovery in Molecular Medicine Developed Using Serum Small Extracellular Vesicle Associated miRNAs and the Barrett's Oesophagus Disease Spectrum.

The biomarker development field within molecular medicine remains limited by the methods that are available for building predictive models. We developed an efficient method for conservatively estimating confidence intervals for the cross validation-derived prediction errors of biomarker models. This new method was investigated for its ability to improve the capacity of our previously developed method, StaVarSel, for selecting stable biomarkers. Compared with the standard cross validation method, StaVarSel markedly improved the estimated generalisable predictive capacity of serum miRNA biomarkers for the detection of disease states that are at increased risk of progressing to oesophageal adenocarcinoma. The incorporation of our new method for conservatively estimating confidence intervals into StaVarSel resulted in the selection of less complex models with increased stability and improved or similar predictive capacities. The methods developed in this study have the potential to improve progress from biomarker discovery to biomarker driven translational research.

Mutant p53 Mediates Sensitivity to Cancer Treatment Agents in Oesophageal Adenocarcinoma Associated with MicroRNA and SLC7A11 Expression.

TP53 gene mutations occur in 70% of oesophageal adenocarcinomas (OACs). Given the central role of p53 in controlling cellular response to therapy we investigated the role of mutant (mut-) p53 and SLC7A11 in a CRISPR-mediated JH-EsoAd1 TP53 knockout model. Response to 2 Gy irradiation, cisplatin, 5-FU, 4-hydroxytamoxifen, and endoxifen was assessed, followed by a TaqMan OpenArray qPCR screening for differences in miRNA expression. Knockout of mut-p53 resulted in increased chemo- and radioresistance (2 Gy survival fraction: 38% vs. 56%, p < 0.0001) and in altered miRNA expression levels. Target mRNA pathways analyses indicated several potential mechanisms of treatment resistance. SLC7A11 knockdown restored radiosensitivity (2 Gy SF: 46% vs. 73%; p = 0.0239), possibly via enhanced sensitivity to oxidative stress. Pathway analysis of the mRNA targets of differentially expressed miRNAs indicated potential involvement in several pathways associated with apoptosis, ribosomes, and p53 signaling pathways. The data suggest that mut-p53 in JH-EsoAd1, despite being classified as non-functional, has some function related to radio- and chemoresistance. The results also highlight the important role of SLC7A11 in cancer metabolism and redox balance and the influence of p53 on these processes. Inhibition of the SLC7A11-glutathione axis may represent a promising approach to overcome resistance associated with mut-p53.

MicroRNA Profiling in Oesophageal Adenocarcinoma Cell Lines and Patient Serum Samples Reveals a Role for miR-451a in Radiation Resistance.

Many patients with Oesophageal Adenocarcinoma (OAC) do not benefit from chemoradiotherapy treatment due to therapy resistance. To better understand the mechanisms involved in resistance and to find potential biomarkers, we investigated the association of microRNAs, which regulate gene expression, with the response to individual treatments, focusing on radiation. Intrinsic radiation resistance and chemotherapy drug resistance were assessed in eight OAC cell lines, and miRNA expression profiling was performed via TaqMan OpenArray qPCR. miRNAs discovered were either uniquely associated with resistance to radiation, cisplatin, or 5-FU, or were common to two or all three of the treatments. Target mRNA pathway analyses indicated several potential mechanisms of treatment resistance. miRNAs associated with the in vitro treatment responses were then investigated for association with pathologic response to neoadjuvant chemoradiotherapy (nCRT) in pre-treatment serums of patients with OAC. miR-451a was associated uniquely with resistance to radiation treatment in the cell lines, and with the response to nCRT in patient serums. Inhibition of miR-451a in the radiation resistant OAC cell line OE19 increased radiosensitivity (Survival Fraction 73% vs. 87%, p = 0.0003), and altered RNA expression. Pathway analysis of effected small non-coding RNAs and corresponding mRNA targets suggest potential mechanisms of radiation resistance in OAC.

Serum outperforms plasma in small extracellular vesicle microRNA biomarker studies of adenocarcinoma of the esophagus.

BACKGROUND: Circulating microRNAs (miRNAs) are potential biomarkers for many diseases. However, they can originate from non-disease specific sources, such as blood cells, and compromise the investigations for miRNA biomarkers. While small extracellular vesicles (sEVs) have been suggested to provide a purer source of circulating miRNAs for biomarkers discovery, the most suitable blood sample for sEV miRNA biomarker studies has not been defined. AIM: To compare the miRNA profiles between matched serum and plasma sEV preparations to determine their suitability for biomarker studies. METHODS: Matched serum and plasma samples were obtained from 10 healthy controls and 10 patients with esophageal adenocarcinoma. sEV isolates were prepared from serum and plasma using ExoQuickTM and quantified using NanoSight. RNA was extracted from sEV preparations with the miRNeasy Serum/Plasma kit and profiled using the Taqman Openarray qPCR. The overall miRNA content and the expression of specific miRNAs of reported vesicular and non-vesicular origins were compared between serum and plasma sEV preparations. The diagnostic performance of a previously identified multi-miRNA biomarker panel for esophageal adenocarcinoma was also compared. RESULTS: The overall miRNA content was higher in plasma sEV preparations (480 miRNAs) and contained 97.5% of the miRNAs found in the serum sEV preparations (412 miRNAs).The expression of commonly expressed miRNAs was highly correlated (Spearman's R = 0.87, P < 0.0001) between the plasma and serum sEV preparations, but was consistently higher in the plasma sEV preparations. Specific blood-cell miRNAs (hsa-miR-223-3p, hsa-miR-451a, miR-19b-3p, hsa-miR-17-5p, hsa-miR-30b-5p, hsa-miR-106a-5p, hsa-miR-150-5p and hsa-miR-92a-3p) were expressed at 2.7 to 9.6 fold higher levels in the plasma sEV preparations compared to serum sEV preparations (P < 0.05). In plasma sEV preparations, the percentage of protein-associated miRNAs expressed at relatively higher levels (Ct 20-25) was greater than serum sEV preparations (50% vs 31%). While the percentage of vesicle-associated miRNAs expressed at relatively higher levels was greater in the serum sEV preparations than plasma sEV preparations (70% vs 44%). A 5-miRNA biomarker panel produced a higher cross validated accuracy for discriminating patients with esophageal adenocarcinoma from healthy controls using serum sEV preparations compared with plasma sEV preparations (AUROC 0.80 vs 0.54, P < 0.05). CONCLUSION: Although plasma sEV preparations contained more miRNAs than serum sEV preparations, they also contained more miRNAs from non-vesicle origins. Serum appears to be more suitable than plasma for sEV miRNAs biomarkers studies.

Identification of microRNA Biomarkers of Response to Neoadjuvant Chemoradiotherapy in Esophageal Adenocarcinoma Using Next Generation Sequencing.

BACKGROUND: Clinical trials report improved overall survival following neoadjuvant chemoradiotherapy in patients undergoing surgery for esophageal adenocarcinoma, with a 10-15% survival improvement. MicroRNAs (miRNAs) are small noncoding RNAs that are known to direct the behavior of cancers, including response to treatment. We investigated the ability of miRNAs to predict outcomes after neoadjuvant chemoradiotherapy. METHODS: Endoscopic biopsies from esophageal adenocarcinomas were obtained before neoadjuvant chemoradiotherapy and esophagectomy. miRNA levels were measured in the biopsies using next generation sequencing and compared with pathological response in the surgical resection, and subsequent survival. miRNA ratios that predicted pathological response were identified by Lasso regression and leave-one-out cross-validation. Association between miRNA ratio candidates and relapse-free survival was assessed using Kaplan-Meier analysis. Cox regression and Harrell's C analyses were performed to assess the predictive performance of the miRNAs. RESULTS: Two miRNA ratios (miR-4521/miR-340-5p and miR-101-3p/miR-451a) that predicted the pathological response to neoadjuvant chemoradiotherapy were found to be associated with relapse-free survival. Pretreatment expression of these two miRNA ratios, pretreatment tumor differentiation, posttreatment AJCC histopathological tumor regression grading, and posttreatment tumor clearance/margins were significant factors associated with survival in Cox regression analysis. Multivariate analysis of the two ratios together with pretherapy factors resulted in a risk prediction accuracy of 85% (Harrell's C), which was comparable with the prediction accuracy of the AJCC treatment response grading (77%). CONCLUSIONS: miRNA-ratio biomarkers identified using next generation sequencing can be used to predict disease free survival following neoadjuvant chemoradiotherapy and esophagectomy in patients with esophageal adenocarcinoma.

MicroRNA profile in neosquamous esophageal mucosa following ablation of Barrett's esophagus.

AIM: To investigate the microRNA expression profile in esophageal neosquamous epithelium from patients who had undergone ablation of Barrett's esophagus. METHODS: High throughput screening using TaqMan® Array Human MicroRNA quantitative PCR was used to determine expression levels of 754 microRNAs in distal esophageal mucosa (1 cm above the gastro-esophageal junction) from 16 patients who had undergone ablation of non-dysplastic Barrett's esophagus using argon plasma coagulation vs pretreatment mucosa, post-treatment proximal normal non-treated esophageal mucosa, and esophageal mucosal biopsies from 10 controls without Barrett's esophagus. Biopsies of squamous mucosa were also taken from 5 cm above the pre-ablation squamo-columnar junction. Predicted mRNA target pathway analysis was used to investigate the functional involvement of differentially expressed microRNAs. RESULTS: Forty-four microRNAs were differentially expressed between control squamous mucosa vs post-ablation neosquamous mucosa. Nineteen microRNAs were differentially expressed between post-ablation neosquamous and post-ablation squamous mucosa obtained from the more proximal non-treated esophageal segment. Twelve microRNAs were differentially expressed in both neosquamous vs matched proximal squamous mucosa and neosquamous vs squamous mucosa from healthy patients. Nine microRNAs (miR-424-5p, miR-127-3p, miR-98-5p, miR-187-3p, miR-495-3p, miR-34c-5p, miR-223-5p, miR-539-5p, miR-376a-3p, miR-409-3p) were expressed at higher levels in post-ablation neosquamous mucosa than in matched proximal squamous and healthy squamous mucosa. These microRNAs were also more highly expressed in Barrett's esophagus mucosa than matched proximal squamous and squamous mucosa from controls. Target prediction and pathway analysis suggests that these microRNAs may be involved in the regulation of cell survival signalling pathways. Three microRNAs (miR-187-3p, miR-135b-5p and miR-31-5p) were expressed at higher levels in post-ablation neosquamous mucosa than in matched proximal squamous and healthy squamous mucosa. These miRNAs were expressed at similar levels in pre-ablation Barrett's esophagus mucosa, matched proximal squamous and squamous mucosa from controls. Target prediction and pathway analysis suggests that these microRNAs may be involved in regulating the expression of proteins that contribute to barrier function. CONCLUSION: Neosquamous mucosa arising after ablation of Barrett's esophagus expresses microRNAs that may contribute to decreased barrier function and microRNAs that may be involved in the regulation of survival signaling pathways.

Toward More Efficient Surveillance of Barrett's Esophagus: Identification and Exclusion of Patients at Low Risk of Cancer.

BACKGROUND: Endoscopic surveillance of Barrett's esophagus (BE) is probably not cost-effective. A sub-population with BE at increased risk of high-grade dysplasia (HGD) or esophageal adenocarcinoma (EAC) who could be targeted for cost-effective surveillance was sought. METHODS: The outcome for BE surveillance from 2003 to 2012 in a structured program was reviewed. Incidence rates and incidence rate ratios for developing HGD or EAC were calculated. Risk stratification identified individuals who could be considered for exclusion from surveillance. A health-state transition Markov cohort model evaluated the cost-effectiveness of focusing on higher-risk individuals. RESULTS: During 2067 person-years of follow-up of 640 patients, 17 individuals progressed to HGD or EAC (annual IR 0.8%). Individuals with columnar-lined esophagus (CLE) ≥2 cm had an annual IR of 1.2% and >8-fold increased relative risk of HGD or EAC, compared to CLE <2 cm [IR-0.14% (IRR 8.6, 95% CIs 4.5-12.8)]. Limiting the surveillance cohort after the first endoscopy to individuals with CLE ≥2 cm, or dysplasia, followed by a further restriction after the second endoscopy-exclusion of patients without intestinal metaplasia-removed 296 (46%) patients, and 767 (37%) person-years from surveillance. Limiting surveillance to the remaining individuals reduced the incremental cost-effectiveness ratio from US$60,858 to US$33,807 per quality-adjusted life year (QALY). Further restrictions were tested but failed to improve cost-effectiveness. CONCLUSIONS: Based on stratification of risk, the number of patients requiring surveillance can be reduced by at least a third. At a willingness-to-pay threshold of US$50,000 per QALY, surveillance of higher-risk individuals becomes cost-effective.

Measuring Outcomes of Laparoscopic Anti-reflux Surgery: Quality of Life Versus Symptom Scores?

INTRODUCTION: Outcome following fundoplication for gastroesophageal reflux can be measured using objective tests, symptom scores and quality of life (QoL) measures. Which is best and how these assessments correlate is uncertain. To determine the utility of assessment measures we compared a general QoL measure (SF-36) and a disease-specific measure (GERD-hr-QoL) with symptom and satisfaction scores in individuals following fundoplication. METHODS: 329 individuals underwent fundoplication between 2000 and 2015 in 2 centres in Australia and the Netherlands. Patients were assessed before and 3, 12 and 24 months after surgery using 10-point Likert scales to assess heartburn and satisfaction, the SF-36 questionnaire and the GERD-hr-QoL questionnaire. SF-36 scores were converted into component scores: Physical Component Scale (PCS) score and Mental Component Scale (MCS) score. Correlations between QoL measures and clinical outcomes were determined. RESULTS: Surgery relieved heartburn (7.0 vs. 0.0 median, P < 0.001) and patients were highly satisfied with the outcome (median 9.0). PCS and MCS scores improved after surgery (PCS 40.9 vs. 46.0, P < 0.001; MCS 47.6 vs. 50.3, P = 0.027). GERD-hr-QoL scores also improved after surgery (15.7 vs. 3.7, P < 0.001). Correlations between PCS and MCS scores versus heartburn and satisfaction scores were generally weak or absent. However, correlations between GERD-hr-QoL versus heartburn and satisfaction scores were moderate to strong. CONCLUSION: Despite improvements in scores, the SF-36 correlated poorly with clinical outcome measures, and its use to measure outcome following fundoplication is questioned. However, the GERD-hr-QoL correlated well with the symptom scores, suggesting this disease-specific QoL measure is a better tool for assessing anti-reflux surgery outcome.

Circulating Serum Exosomal miRNAs As Potential Biomarkers for Esophageal Adenocarcinoma.

BACKGROUND: The poor prognosis and rising incidence of esophageal adenocarcinoma highlight the need for improved detection methods. The potential for circulating microRNAs (miRNAs) as biomarkers in other cancers has been shown, but circulating miRNAs have not been well characterized in esophageal adenocarcinoma. We investigated whether circulating exosomal miRNAs have potential to discriminate individuals with esophageal adenocarcinoma from healthy controls and non-dysplastic Barrett's esophagus. METHODS: Seven hundred fifty-eight miRNAs were profiled in serum circulating exosomes from a cohort of 19 healthy controls, 10 individuals with Barrett's esophagus, and 18 individuals with locally advanced esophageal adenocarcinoma. MiRNA expression was assessed using all possible permutations of miRNA ratios per individual. Four hundred eight miRNA ratios were differentially expressed in individuals with cancer compared to controls and Barrett's esophagus (Mann-Whitney U test, P < 0.05). The 179/408 ratios discriminated esophageal adenocarcinoma from healthy controls and Barrett's esophagus (linear regression, P < 0.05; area under receiver operating characteristic (ROC) > 0.7, P < 0.05). A multi-biomarker panel (RNU6-1/miR-16-5p, miR-25-3p/miR-320a, let-7e-5p/miR-15b-5p, miR-30a-5p/miR-324-5p, miR-17-5p/miR-194-5p) demonstrated enhanced specificity and sensitivity (area under ROC = 0.99, 95% CI 0.96-1.0) over single miRNA ratios to distinguish esophageal adenocarcinoma from controls and Barrett's esophagus. CONCLUSIONS: This study highlights the potential for serum exosomal miRNAs as biomarkers for the detection of esophageal adenocarcinoma.

A fixed-point algorithm for estimating amplification efficiency from a polymerase chain reaction dilution series.

BACKGROUND: The polymerase chain reaction amplifies and quantifies small amounts of DNA. It is a cyclic process, during each cycle of which each strand of template DNA is copied with probability approaching one: the amount of DNA approximately doubles and this amount can be estimated fluorimetrically each cycle, producing a set of fluorescence values hereafter referred to as the amplification curve. Commonly the biological question of relevance is one of the ratio of DNA concentrations in two samples: a ratio that is deduced by comparing the two amplification curves, usually by way of a plot of fluorescence against cycle number. Central to this analysis is measuring the extent to which one amplification curve is shifted relative to the other, a measurement often accomplished by defining a threshold or quantification cycle, C q , for each curve: the fractional cycle number at which fluorescence reaches some threshold or at which some other criterion (maximum slope, maximum rate of change of slope) is satisfied. We propose an alternative where position is measured relative to a reference curve; position equates to the cycle shift which maximizes the correlation between the reference and the observed fluorescence sequence. A key parameter of the reference curve is obtained by fixed-point convergence. RESULTS: We consider the analysis of dilution series constructed for the estimation of qPCR amplification efficiency. The estimate of amplification efficiency is based on the slope of the regression line when the C q is plotted against the logarithm of dilution. We compare the approach to three commonly used methods for determining C q ; each is applied to publicly accessible calibration data sets, and to ten from our own laboratory. As in the established literature we judge their relative merits both from the standard deviation of the slope of the calibration curve, and from the variance in C q for replicate fluorescence curves. CONCLUSIONS: The approach does not require modification of experimental protocols, and can be applied retrospectively to existing data. We recommend that it be added to the methodological toolkit with which laboratories interpret their real-time PCR data.

Cost-effectiveness of endoscopic surveillance of non-dysplastic Barrett's esophagus.

BACKGROUND: Endoscopic surveillance for non-dysplastic Barrett's esophagus (BE) is contentious and its cost effectiveness unclear. OBJECTIVE: To perform an economic analysis of endoscopic surveillance strategies. DESIGN: Cost-utility analysis by using a simulation Markov model to synthesize evidence from large epidemiologic studies and clinical data for surveillance, based on international guidelines, applied in a coordinator-managed surveillance program. SETTING: Tertiary care hospital, South Australia. PATIENTS: A total of 2040 patient-years of follow-up. INTERVENTION: (1) No surveillance, (2) 2-yearly endoscopic surveillance of patients with non-dysplastic BE and 6-monthly surveillance of patients with low-grade dysplasia, (3) a hypothetical strategy of biomarker-modified surveillance. MAIN OUTCOME MEASUREMENTS: U.S. cost per quality-adjusted life year (QALY) ratios. RESULTS: Compared with no surveillance, surveillance produced an estimated incremental cost per QALY ratio of $60,858. This was reduced to $38,307 when surveillance practice was modified by a hypothetical biomarker-based strategy. Sensitivity analyses indicated that the likelihood that surveillance alone was cost-effective compared with no surveillance was 16.0% and 60.6% if a hypothetical biomarker-based strategy was added to surveillance, at an acceptability threshold of $100,000 per QALY gained. LIMITATIONS: Treatment options for BE that overlap those for symptomatic GERD were omitted. CONCLUSION: By using best available estimates of the malignant potential of BE, endoscopic surveillance of patients with non-dysplastic BE is unlikely to be cost-effective for the majority of patients and depends heavily on progression rates between dysplasia grades. However, strategies that modify surveillance according to cancer risk might be cost-effective, provided that high-risk individuals can be identified and prioritized for surveillance.

Cost-effectiveness of Barrett's oesophagus screening and surveillance.

Endoscopic screening and surveillance of patients with Barrett's oesophagus to detect oesophageal cancer at earlier stages is contentious. As a consequence, their cost-effectiveness is also debatable. Current health economic evidence shows mixed results for demonstrating their value, mainly due to varied assumptions around progression rates to cancer, quality of life and treatment pathways. No randomized controlled trial exists to definitively support the efficacy of surveillance programs and one is unlikely to be undertaken. Contemporary treatment, cost and epidemiological data to contribute to cost-effectiveness analyses are needed. Risk assessment to stratify patients at low- or high-risk of developing cancer should improve cost-effectiveness outcomes as higher gains will be seen for those at higher risk, and medical resource use will be avoided in those at lower risk. Rapidly changing technologies for imaging, biomarker testing and less-invasive endoscopic treatments also promise to lower health system costs and avoid adverse events in patients.

Can miRNA profiling allow us to determine which patients with esophageal cancer will respond to chemoradiotherapy?

Evaluation of: Ko MA, Zehong G, Virtanen C et al. miRNA expression profiling of esophageal cancer before and after induction chemoradiotherapy. Ann. Thorac. Surg. 94(4), 1094-1103 (2012). Most patients undergoing surgery for esophageal cancer are treated before surgery with chemotherapy and radiotherapy. However, some tumors respond poorly to these treatments. The article under evaluation profiled miRNA levels in esophageal cancers from patients who did respond to chemoradiotherapy versus those who did not. A large number of miRNAs were differentially expressed between responders versus nonresponders, and patients with either decreased miR-135b or increased miR-145 expression in cancer tissue had improved disease-free survival. Although this study has several limitations, including a mixed cohort of patients with adenocarcinoma and squamous cell carcinoma, and the absence of a validation set of patients, the results do suggest that a miRNA profiling approach may be able to circumvent one of the primary challenges for biomarker development, molecular heterogeneity.

MicroRNAs and esophageal cancer--implications for pathogenesis and therapy.

There are several microRNAs that have been consistently reported to be differentially expressed in esophageal squamous cell carcinoma vs. normal squamous tissue, with prognostic associations for miR-21 (invasion, positive nodes, decreased survival), miR-143 (disease recurrence, invasion depth), and miR-375 (inversely correlated with advanced stage, distant metastasis, poor overall survival, and disease-free survival). There is also evidence that miR-375 regulates gene expression associated with resistance to chemotherapy. Hence, microRNA expression assays have the potential to provide clinically relevant information about prognosis and potential response to chemotherapy in patients with esophageal squamous cell carcinoma. Results are inconsistent, however, for microRNAs across different studies for esophageal adenocarcinoma (EAC) vs. its precursor lesion Barrett's esophagus. These inconsistencies may partly result from pathological and/or molecular heterogeneity in both Barrett's esophagus and EAC, but may also result from differences in study designs or different choices of comparator tissues. Despite these inconsistencies, however, several mRNA/protein targets have been identified, the cancer related biology of some of these targets is well understood, and there are clinico-pathological associations for some of these mRNA targets. MicroRNAs also have potential for use in therapy for esophageal cancers. The development of new delivery methods, such as minicells and autologous microvesicles, and molecular modifications such as the addition of aromatic benzene pyridine analogs, have facilitated the exploration of the effects of therapeutic microRNAs in vivo. These approaches are producing encouraging results, with one technology in a phase I/IIa clinical trial.

Chronic elevation of pulmonary microvascular pressure in chronic heart failure reduces bi-directional pulmonary fluid flux.

AIMS: Chronic heart failure leads to pulmonary vascular remodelling and thickening of the alveolar-capillary barrier. We examined whether this protective effect may slow resolution of pulmonary oedema consistent with decreased bi-directional fluid flux. METHODS AND RESULTS: Seven weeks following left coronary artery ligation, we measured both fluid flux during an acute rise in left atrial pressure (n = 29) and intrinsic alveolar fluid clearance (n = 45) in the isolated rat lung. Chronic elevation of pulmonary microvascular pressure prevented pulmonary oedema and decreased lung compliance when left atrial pressure was raised to 20 cmH2O, and was associated with reduced expression of endothelial aquaporin 1 (P = 0.03). However, no other changes were found in mediators of fluid flux or cellular fluid channels. In isolated rat lungs, chronic LV dysfunction (LV end-diastolic pressure and infarct circumference) was also inversely related to alveolar fluid clearance (P ≤ 0.001). The rate of pulmonary oedema reabsorption was estimated by plasma volume expansion in eight patients with a previous clinical history of chronic heart failure and eight without, who presented with acute pulmonary oedema. Plasma volume expansion was reduced at 24 h in those with chronic heart failure (P = 0.03). CONCLUSIONS: Chronic elevation of pulmonary microvascular pressure in CHF leads to decreased intrinsic bi-directional fluid flux at the alveolar-capillary barrier. This adaptive response defends against alveolar flooding, but may delay resolution of alveolar oedema.

Molecular biomarkers and ablative therapies for Barrett's esophagus.

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

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

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

COX-2 mRNA is increased in oesophageal mucosal cells by a proton pump inhibitor.

BACKGROUND: Barrett's oesophagus develops in some individuals with gastro-oesophageal reflux and is the precursor to oesophageal adenocarcinoma. Proton pump inhibitors (PPIs) suppress gastric acid production and are used to treat reflux. Clinical trials suggest that cyclooxygenase (COX) inhibitors might prevent oesophageal cancer, although PPIs could offset this by increasing COX-2 expression in Barrett's oesophagus. To investigate this, we evaluated the impact of a PPI on COX expression in oesophageal mucosal cells. METHODS: The effect of the PPI esomeprazole on COX-1 and COX-2 mRNA levels in oesophageal cells was determined. Oesophageal cell lines OE33 (adenocarcinoma-derived) and HET-1A (immortalized squamous cells) and a control intestinal cell line HT29 (colon carcinoma) were treated for 24 h, with increasing concentrations of the esomeprazole. RESULTS: COX-2, but not COX-1, mRNA levels dose-dependently increased in OE33 and HET-1A cells versus esomeprazole concentration. COX-2 mRNA levels did not increase in HT29 cells. CONCLUSIONS: Exposure to esomeprazole increases COX-2 mRNA in oesophageal cells. This might contribute to the lack of benefit for COX inhibitors for oesophageal cancer prevention in recent clinical studies.