Real-world implementation of non-endoscopic triage testing for Barrett's oesophagus during COVID-19

BACKGROUND

The Coronavirus pandemic (COVID-19) curtailed endoscopy services, adding to diagnostic backlogs. Building on trial evidence for a non-endoscopic oesophageal cell collection device coupled with biomarkers (Cytosponge), an implementation pilot was launched for patients on waiting lists for reflux and Barrett's oesophagus surveillance.

AIMS

(i) To review reflux referral patterns and Barrett's surveillance practices. (ii) To evaluate the range of Cytosponge findings and impact on endoscopy services.

DESIGN AND METHODS

Cytosponge data from centralized laboratory processing (trefoil factor 3 (TFF3) for intestinal metaplasia (IM), haematoxylin & eosin for cellular atypia and p53 for dysplasia) over a 2-year period were included.

RESULTS

A total of 10 577 procedures were performed in 61 hospitals in England and Scotland, of which 92.5% (N = 9784/10 577) were sufficient for analysis. In the reflux cohort (N = 4074 with gastro-oesophageal junction sampling), 14.7% had one or more positive biomarkers (TFF3: 13.6% (N = 550/4056), p53: 0.5% (21/3974), atypia: 1.5% (N = 63/4071)), requiring endoscopy. Among samples from individuals undergoing Barrett's surveillance (N = 5710 with sufficient gland groups), TFF3-positivity increased with segment length (odds ratio = 1.37 per cm (95% confidence interval: 1.33-1.41, P < 0.001)). Some surveillance referrals (21.5%, N = 1175/5471) had ≤1 cm segment length, of which 65.9% (707/1073) were TFF3 negative. Of all surveillance procedures, 8.3% had dysplastic biomarkers (4.0% (N = 225/5630) for p53 and 7.6% (N = 430/5694) for atypia), increasing to 11.8% (N = 420/3552) in TFF3+ cases with confirmed IM and 19.7% (N = 58/294) in ultra-long segments.

CONCLUSIONS

Cytosponge-biomarker tests enabled targeting of endoscopy services to higher-risk individuals, whereas those with TFF3 negative ultra-short segments could be reconsidered regarding their Barrett's oesophagus status and surveillance requirements. Long-term follow-up will be important in these cohorts.

GWAS meta-analysis of 16 790 patients with Barrett's oesophagus and oesophageal adenocarcinoma identifies 16 novel genetic risk loci and provides insights into disease aetiology beyond the single marker level

OBJECTIVE

Oesophageal cancer (EC) is the sixth leading cause of cancer-related deaths. Oesophageal adenocarcinoma (EA), with Barrett's oesophagus (BE) as a precursor lesion, is the most prevalent EC subtype in the Western world. This study aims to contribute to better understand the genetic causes of BE/EA by leveraging genome wide association studies (GWAS), genetic correlation analyses and polygenic risk modelling.

DESIGN

We combined data from previous GWAS with new cohorts, increasing the sample size to 16 790 BE/EA cases and 32 476 controls. We also carried out a transcriptome wide association study (TWAS) using expression data from disease-relevant tissues to identify BE/EA candidate genes. To investigate the relationship with reported BE/EA risk factors, a linkage disequilibrium score regression (LDSR) analysis was performed. BE/EA risk models were developed combining clinical/lifestyle risk factors with polygenic risk scores (PRS) derived from the GWAS meta-analysis.

RESULTS

The GWAS meta-analysis identified 27 BE and/or EA risk loci, 11 of which were novel. The TWAS identified promising BE/EA candidate genes at seven GWAS loci and at five additional risk loci. The LDSR analysis led to the identification of novel genetic correlations and pointed to differences in BE and EA aetiology. Gastro-oesophageal reflux disease appeared to contribute stronger to the metaplastic BE transformation than to EA development. Finally, combining PRS with BE/EA risk factors improved the performance of the risk models.

CONCLUSION

Our findings provide further insights into BE/EA aetiology and its relationship to risk factors. The results lay the foundation for future follow-up studies to identify underlying disease mechanisms and improving risk prediction.

Multi-omic cross-sectional cohort study of pre-malignant Barrett's esophagus reveals early structural variation and retrotransposon activity

Barrett's esophagus is a pre-malignant lesion that can progress to esophageal adenocarcinoma. We perform a multi-omic analysis of pre-cancer samples from 146 patients with a range of outcomes, comprising 642 person years of follow-up. Whole genome sequencing reveals complex structural variants and LINE-1 retrotransposons, as well as known copy number changes, occurring even prior to dysplasia. The structural variant burden captures the most variance across the cohort and genomic profiles do not always match consensus clinical pathology dysplasia grades. Increasing structural variant burden is associated with: high levels of chromothripsis and breakage-fusion-bridge events; increased expression of genes related to cell cycle checkpoint, DNA repair and chromosomal instability; and epigenetic silencing of Wnt signalling and cell cycle genes. Timing analysis reveals molecular events triggering genomic instability with more clonal expansion in dysplastic samples. Overall genomic complexity occurs early in the Barrett's natural history and may inform the potential for cancer beyond the clinically discernible phenotype.

Longitudinal tracking of 97 esophageal adenocarcinomas using liquid biopsy sampling

BACKGROUND

The incidence of esophageal adenocarcinoma (EAC) is rapidly rising and has a 5-year survival rate of <20%. Beyond TNM (tumor-node-metastasis) staging, no reliable risk stratification tools exist and no large-scale studies have profiled circulating tumor DNA (ctDNA) at relapse in EAC. Here we analyze the prognostic potential of ctDNA dynamics in EAC, taking into account clonal hematopoiesis with indeterminate potential (CHIP).

PATIENTS AND METHODS

A total of 245 samples from 97 patients treated with neoadjuvant chemotherapy and surgery were identified from the prospective national UK Oesophageal Cancer Clinical and Molecular Stratification (OCCAMS) consortium data set. A pan-cancer ctDNA panel comprising 77 genes was used. Plasma and peripheral blood cell samples were sequenced to a mean depth of 7082× (range 2196-28 524) and ctDNA results correlated with survival.

RESULTS

Characteristics of the 97 patients identified were as follows: 83/97 (86%) male, median age 68 years (SD 9.5 years), 100% cT3/T4, 75% cN+. EAC-specific drivers had higher variant allele fractions than passenger mutations. Using stringent quality criteria 16/79 (20%) were ctDNA positive following resection; recurrence was observed in 12/16 (75%) of these. As much as 78/97 (80%) had CHIP analyses that enabled filtering for CHIP variants, which were found in 18/78 (23%) of cases. When CHIP was excluded, 10/63 (16%) patients were ctDNA positive and 9/10 of these (90%) recurred. With correction for CHIP, median cancer-specific survival for ctDNA-positive patients was 10.0 months versus 29.9 months for ctDNA-negative patients (hazard ratio 5.55, 95% confidence interval 2.42-12.71; P = 0.0003). Similar outcomes were observed for disease-free survival.

CONCLUSIONS

We demonstrate in a large, national, prospectively collected data set that ctDNA in plasma following surgery for EAC is prognostic for relapse. Inclusion of peripheral blood cell samples can reduce or eliminate false positives from CHIP. In future, post-operative ctDNA could be used to risk stratify patients into high- and low-risk groups for intensification or de-escalation of adjuvant chemotherapy.

A biomarker panel predicts progression of Barrett's esophagus to esophageal adenocarcinoma

Progression from Barrett's esophagus (BE) to esophageal adenocarcinoma (EAC) is uncommon but the consequences are serious. Predictors of progression are essential to optimize resource utilization. This study assessed the utility of a promising panel of biomarkers applicable to routine paraffin embedded biopsies (FFPE) to predict progression of BE to EAC in a large population-based, nested case-control study.We utilized the Amsterdam-based ReBus nested case-control cohort. BE patients who progressed to high-grade dysplasia (HGD)/EAC (n = 130) and BE patients who never progressed (n = 130) were matched on age, sex, length of the BE segment, and duration of endoscopic surveillance. All progressors had minimum 2 years of endoscopic surveillance without HGD/EAC to exclude prevalent neoplasia. We assessed abnormal DNA content, p53, Cyclin A, and Aspergillus oryzae lectin (AOL) in FFPE sections. We performed conditional logistic regression analysis to estimate odds ratio (OR) of progression based on biomarker status.Expert LGD (OR, 8.3; 95% CI, 1.7-41.0), AOL (3 vs. 0 epithelial compartments abnormal; OR, 3.6; 95% CI, 1.2-10.6) and p53 (OR, 2.3; 95% CI, 1.2-4.6) were independently associated with neoplastic progression. Cyclin A did not predict progression and DNA ploidy analysis by image cytometry was unsuccessful in the majority of cases, both were excluded from the multivariate analysis. The multivariable biomarker model had an area under the receiver operating characteristic curve of 0.73.Expert LGD, AOL, and p53 independently predict neoplastic progression in BE patients and are applicable to routine practice. These biomarkers can aid in selecting patients for endoscopic ablation or more intensive surveillance.

Multicentre cohort study to define and validate pathological assessment of response to neoadjuvant therapy in oesophagogastric adenocarcinoma

BACKGROUND

This multicentre cohort study sought to define a robust pathological indicator of clinically meaningful response to neoadjuvant chemotherapy in oesophageal adenocarcinoma.

METHODS

A questionnaire was distributed to 11 UK upper gastrointestinal cancer centres to determine the use of assessment of response to neoadjuvant chemotherapy. Records of consecutive patients undergoing oesophagogastric resection at seven centres between January 2000 and December 2013 were reviewed. Pathological response to neoadjuvant chemotherapy was assessed using the Mandard Tumour Regression Grade (TRG) and lymph node downstaging.

RESULTS

TRG (8 of 11 centres) was the most widely used system to assess response to neoadjuvant chemotherapy, but there was discordance on how it was used in practice. Of 1392 patients, 1293 had TRG assessment; data were available for clinical and pathological nodal status (cN and pN) in 981 patients, and TRG, cN and pN in 885. There was a significant difference in survival between responders (TRG 1-2; median overall survival (OS) not reached) and non-responders (TRG 3-5; median OS 2·22 (95 per cent c.i. 1·94 to 2·51) years; P < 0·001); the hazard ratio was 2·46 (95 per cent c.i. 1·22 to 4·95; P = 0·012). Among local non-responders, the presence of lymph node downstaging was associated with significantly improved OS compared with that of patients without lymph node downstaging (median OS not reached versus 1·92 (1·68 to 2·16) years; P < 0·001).

CONCLUSION

A clinically meaningful local response to neoadjuvant chemotherapy was restricted to the small minority of patients (14·8 per cent) with TRG 1-2. Among local non-responders, a subset of patients (21·3 per cent) derived benefit from neoadjuvant chemotherapy by lymph node downstaging and their survival mirrored that of local responders.

Past, present and future of Barrett's oesophagus

Barrett's oesophagus is a condition which predisposes towards development of oesophageal adenocarcinoma, a highly lethal tumour which has been increasing in incidence in the Western world over the past three decades. There have been tremendous advances in the field of Barrett's oesophagus, not only in diagnostic modalities, but also in therapeutic strategies available to treat this premalignant disease. In this review, we discuss the past, present and future of Barrett's oesophagus. We describe the historical and new evolving diagnostic criteria of Barrett's oesophagus, while also comparing and contrasting the British Society of Gastroenterology guidelines, American College of Gastroenterology guidelines and International Benign Barrett's and CAncer Taskforce (BOBCAT) for Barrett's oesophagus. Advances in endoscopic modalities such as confocal and volumetric laser endomicroscopy, and a non-endoscopic sampling device, the Cytosponge, are described which could aid in identification of Barrett's oesophagus. With regards to therapy we review the evidence for the utility of endoscopic mucosal resection and radiofrequency ablation when coupled with better characterization of dysplasia. These endoscopic advances have transformed the management of Barrett's oesophagus from a primarily surgical disease into an endoscopically managed condition.

Pilot study of cytological testing for oesophageal squamous cell dysplasia in a high-risk area in Northern Iran

Background:

Oesophageal squamous cell carcinoma (ESCC) is a fatal disease with 5-year survival rates of <5% in Northern Iran. Oesophageal squamous dysplasia (ESD) is the precursor histologic lesion of ESCC. This pilot study was conducted to assess the feasibility, safety, and acceptability of non-endoscopic cytological examination of the oesophagus and to provide initial data on the accuracy of cytological atypia for identifying patients with ESD in this very-high-risk area.

Methods:

Randomly selected asymptomatic participants of the Golestan Cohort Study were recruited. A cytological specimen was taken using a capsule sponge device and evaluated for atypical cells. Sections of the cytological specimen were also stained for p53 protein. Patient acceptability was assessed using a visual analogue scale. The cytological diagnosis was compared with a chromoendoscopic examination using Lugol's solution.

Results:

Three hundred and forty-four subjects (43% male, mean (s.d.) age 55.6 (7.9) years) were referred to the study clinic. Three hundred and twelve met eligibility criteria and consented, of which 301 subjects (96.5%) completed both cytological and endoscopic examinations. There were no complications. Most of the participants (279; 92.7%) were satisfied with the examination. The sensitivity and specificity of the cytological examination for identifying subjects with high-grade ESD were 100 and 97%, respectively. We found an accuracy of 100% (95% CI=99–100%) for a combination of cytological examination and p53 staining to detect high-grade ESD.

Conclusions:

The capsule sponge methodology seems to be a feasible, safe, and acceptable method for diagnosing precancerous lesions of the oesophagus in this population, with promising initial accuracy data for the detection of high-grade ESD.

Endoscopic TriModal imaging and biomarkers for neoplasia conjoined: a feasibility study in Barrett's esophagus

In Barrett's esophagus (BE), the normal squamous lining of the esophagus is replaced by specialized columnar epithelium. Endoscopic surveillance with autofluorescence imaging (AFI) and molecular biomarkers have been studied separately to detect early neoplasia (EN) in BE. The combination of advanced-imaging modalities and biomarkers has not been investigated; AFI may help detecting biomarkers as a risk-stratification tool. We retrospectively evaluated a cohort of patients undergoing endoscopy for EN in BE with AFI and correlated five biomarkers (HPP1, RUNX3, p16, cyclin A, and p53) in tissue samples with AFI and dysplasia status. Fifty-eight samples from a previous prospective study were selected: 15 true-positive (TP: AFI-positive, EN), 21 false-positive (FP: AFI-positive, no EN), 12 true-negative (TN1; AFI-negative, no EN in sample), 10 true-negative (TN2: AFI-negative, no EN in esophagus). Methylation-specific RT-PCR was performed for HPP1, RUNX3, p16, and immunohistochemistry for cyclin A, p53. P < 0.05 was considered statistically significant. Bonferroni correction was used for multiple comparisons. P16, cyclin A, p53 correlated with dysplasia (P < 0.01, P = 0.003, P < 0.001, respectively). Increased p16 methylation was observed between TP versus TN2 (P = 0.003) and TN1 versus TN2 (P = 0.04) subgroups, suggesting a field defect. Only p53 correlated with AFI-status (P = 0.003). After exclusion of EN samples, significance was lost. Although correlation with dysplasia status was confirmed for p16, cyclin A and p53, underlining the importance of these biomarkers as an early event in neoplastic progression, none of the investigated biomarkers correlated with AFI status. A larger prospective study is needed to assess the combination of AFI and a larger panel of biomarkers to improve risk stratification in BE.

Integrative analysis of array-comparative genomic hybridisation and matched gene expression profiling data reveals novel genes with prognostic significance in oesophageal adenocarcinoma

BACKGROUND AND AIMS

The incidence of oesophageal adenocarcinoma (OAC) has been increasing rapidly with a dismal survival rate of less than 20%. Understanding the genomic aberrations and biology of this cancer may enhance disease interventions. This study aimed to use genome-wide genomic and expression data to enhance the understanding of OAC pathogenesis and identify groups with differential outcomes.

METHODS

Array-comparative genomic hybridisation (aCGH) analysis was carried out on 56 fresh frozen OAC resection samples with long-term clinical follow-up data. Samples with aberrations were further analysed with whole-genome single-nucleotide polymorphism arrays to confirm aCGH findings. Matched gene expression microarray data were used to identify genes with high copy number-expression correlations. Nested-multiplex PCR on DNA from microdissected specimens and fluorescence in situ hybridisation assays were used for target validation. Immunohistochemistry on the same cohort and independent samples (n=371) was used for subsequent validation. Kaplan-Meier survival analyses were performed based on aCGH data after unsupervised K-means clustering (K=5, 50 iterations) and immunohistochemistry data.

RESULTS

aCGH identified 17 common regions (>5% samples) of gains and 11 common regions of losses, including novel regions in OAC (loci 11p13 and 21q21.2). Integration of aCGH data with matched gene expression microarray data highlighted genes with high copy number-expression correlations: two deletions (p16/CDKN2A, MBNL1) and four gains (EGFR, WT1, NEIL2, MTMR9). Immunohistochemistry demonstrated protein over-expression of targets with gains: EGFR (10%), WT1 (20%), NEIL2 (14%) and MTMR9 (25%). These targets individually (p<0.060) and in combination had prognostic significance (p=0.008). On the genomic level, K-means clustering identified a cluster (32% of cohort) with differential log(2) ratios of 16 CGH probes (p<4×10(-7)) and a worse prognosis (median survival=1.37 years; p=0.015).

CONCLUSIONS

Integration of aCGH and gene expression data identified copy number aberrations and novel genes with prognostic potential in OAC.

Non-endoscopic screening biomarkers for Barrett's oesophagus: from microarray analysis to the clinic

BACKGROUND AND AIMS

Barrett's oesophagus predisposes to oesophageal adenocarcinoma but the majority of patients are undiagnosed. A novel non-endoscopic cytological screening device, called a capsule sponge, makes population-based screening for the disease a feasible option. However, due to the mixed cell population retrieved by the capsule sponge, biomarkers specific for Barrett's oesophagus are required.

METHODS

Three publically available microarray datasets were used to identify putative biomarkers present in Barrett's oesophagus but absent from normal oesophagus and gastric mucosa. Validation was performed by qPCR (n = 10 each of normal oesophagus, Barrett's oesophagus, gastric mucosa) and immunohistochemistry (normal oesophagus, n = 20; Barrett's oesophagus, n = 21; gastric mucosa, n = 24; duodenum, n = 18). The biomarker was then prospectively evaluated on capsule sponge specimens from 47 patients with Barrett's oesophagus and 99 healthy controls.

RESULTS

2/14 genes identified, dopa decarboxylase (DDC) and Trefoil factor 3 (TFF3), were confirmed by qPCR to be upregulated in Barrett's oesophagus compared to normal oesophagus (p<0.01) and gastric mucosa (p<0.01 and p<0.05, respectively). Immunohistochemistry confirmed that DDC protein expression was restricted to Barrett's oesophagus but was confined to <1% of the cells within the crypt compartment. TFF3 protein was expressed to high levels at the luminal surface of Barrett's oesophagus compared to absent expression in normal oesophagus and gastric mucosa (p<0.001). Using the capsule sponge 36/46 patients with Barrett's oesophagus (one inadequate sample) and 6/96 controls were positive for TFF3 giving a sensitivity of 78% and a specificity of 94%.

CONCLUSIONS

TFF3 is a promising marker for Barrett's oesophagus screening since it is expressed at the luminal surface of Barrett's oesophagus but not in adjacent tissue types and may be applied to a non-endoscopic screening device.

Generation and validation of a revised classification for oesophageal and junctional adenocarcinoma

BACKGROUND

Oesophageal adenocarcinoma is the commonest oesophageal malignancy in the West, but is staged using a system designed for squamous cell carcinoma. The aim was to develop and validate a staging system for oesophageal and junctional adenocarcinoma.

METHODS

Patients with oesophageal adenocarcinoma (Siewert types I and II) undergoing oesophagectomy with curative intent were randomly assigned to generation (313 patients) and validation (131) data sets. Outcome in the generation data set was associated with histopathological features; a revised node (N) classification was derived using recursive partitioning and tested on the validation data set.

RESULTS

A revised N classification based on number of involved lymph nodes (N0, none; N1, one to five; N2, six or more) was prognostically significant (P < 0.001). Patients with involved nodes on both sides of the diaphragm, regardless of number, had the same outcome as the N2 group. When applied to the validation data set, the revised classification (including nodal number and location) provided greater discrimination between node-positive patients than the existing system (P < 0.001).

CONCLUSION

A revised N classification based on number and location of involved lymph nodes provides improved prognostic power and incorporates features that may be useful before surgery in clinical management decisions.

The influence of symptom type and duration on the fate of the metaplastic columnar-lined Barrett's oesophagus

BACKGROUND

Prolonged gastro-oesophageal reflux resulting in columnar metaplasia of the oesophagus is the main risk factor for oesophageal adenocarcinoma.

AIM

To examine the duration of symptoms and associations of different symptoms with the development of columnar-lined oesophagus, dysplasia and adenocarcinoma.

METHODS

UK multicentre cohort study of patients with columnar-lined oesophagus whose date of symptom onset (1082 patients) and/or types of symptoms reported (1681 patients) were documented. Follow-up was examined by analysis of histological reports from the registering centers.

RESULTS

Symptoms of dysphagia/odynophagia and nausea/vomiting were associated with development of dysplasia. High-grade dysplasia and adenocarcinoma were associated with dysphagia/odynophagia and weight loss. Median duration from symptom onset to detection of columnar-lined oesophagus without intestinal metaplasia: 2.6 years, columnar-lined oesophagus with intestinal metaplasia: 5.0 years, indefinite changes for dysplasia: 19.3 years and low-grade dysplasia: 30.0 years. One tenth of patients had developed high-grade dysplasia at 9.6 years and one tenth had developed adenocarcinoma at 13.8 years from symptom onset.

CONCLUSIONS

In patients with columnar-lined oesophagus, symptoms of dysphagia/odynophagia and nausea/vomiting were associated with a higher risk of development of dysplasia and adenocarcinoma. There is a trend for longer duration of symptoms to the detection of dysplasia.

Mechanisms and sequelae of E-cadherin silencing in hereditary diffuse gastric cancer

Around 25-40% of cases of hereditary diffuse gastric cancer (HDGC) are caused by heterozygous E-cadherin (CDH1) germline mutations. The mechanisms for loss of the second allele still remain unclear. The aims of this study were to elucidate mechanisms for somatic inactivation of the wild-type CDH1 allele and to seek evidence for cadherin switching. Archival tumour material was analysed from 16 patients with CDH1 germline mutations and seven patients fulfilling HDGC criteria without CDH1 germline mutations. The 16 CDH1 exons were sequenced. E-cadherin promoter methylation was analysed by bisulphite sequencing and pyrosequencing and allele specificity was determined using polymorphic loci. Loss of heterozygosity was analysed using microsatellite markers. Cadherin expression levels were determined by real-time RT-PCR and immunohistochemistry. Six of 16 individuals with germline mutations had at least one second hit mechanism. Two exonic mutations (exon 9 truncating, exon 3 missense) and four intronic mutations which may affect splicing were identified. Tumours from 4/16 individuals had promoter hypermethylation that was restricted to the A allele haplotype in three cases. E-cadherin loss (mRNA and protein) generally correlated with identification of a second hit. In cases without germline E-cadherin mutations there was no evidence for somatic mutation or significant promoter methylation. P-cadherin (>25% cells) was expressed in 7/13 (54%) and 4/5 (80%) with and without germline CDH1 mutations, respectively, independent of complete E-cadherin loss. Overall, inactivation of the second CDH1 allele occurs by mutation and methylation events. Methylation is commonly allele-specific and is uncommon without germline mutations. P-cadherin over-expression commonly occurs in individuals with diffuse type gastric cancer.

Histopathological and molecular analysis of gastrectomy specimens from hereditary diffuse gastric cancer patients has implications for endoscopic surveillance of individuals at risk

Hereditary diffuse gastric cancer (HDGC) is caused by germline E-cadherin (CDH1) mutations in 25-40% of tested families. Management options for asymptomatic mutation carriers are fraught, since endoscopic surveillance can miss cancer foci and prophylactic gastrectomy has profound clinical sequelae. The aims of this study were to evaluate the impact of current surveillance practices on pre-operative diagnosis and to characterize the microscopic lesions in gastrectomy specimens to better inform clinical practice. Histological assessment and mapping of endoscopic surveillance and gastrectomy specimens were performed for eight asymptomatic CDH1 mutation carriers. E-cadherin expression and proliferation were analysed and evidence of epithelial-mesenchymal transition (EMT) was sought by immunohistochemistry for vimentin and cytokeratin 8/18. Four of eight patients had lesions detected at endoscopic surveillance. A median of 20.5 (range 0-66) signet ring foci were identified per gastrectomy (including in situ lesions and pagetoid spread). Foci were predominantly identified in the fundus and body (90% endoscopic biopsies and 85% in gastrectomy). The likelihood of detecting foci pre-operatively was positively correlated with the number of biopsies taken and the number of lesions in the gastrectomy specimen. E-cadherin expression in gastrectomy specimens was reduced or absent in all of the foci compared with the intervening gastric tissue, suggesting that these lesions are polyclonal. The foci had a low proliferative index (<2%) and there was no evidence for EMT. Multiple endoscopic biopsy sampling of the gastric mucosa increases the yield of microscopic cancer foci. The low proliferative index and lack of EMT suggests that these foci may represent an indolent stage of HDGC.

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.

Impaired transforming growth factor beta signalling in Barrett's carcinogenesis due to frequent SMAD4 inactivation

BACKGROUND AND AIMS

Transforming growth factor beta (TGF-beta) is frequently involved in gastrointestinal carcinogenesis although its contribution to oesophageal adenocarcinoma (AC) and its precursor Barrett's oesophageal epithelium (BE) metaplasia are unclear.

METHODS

Expression of TGF-beta signalling components was assessed by reverse transcription-polymerase chain reaction (PCR), western blot, and immunohistochemistry in oesophageal endoscopic biopsies and cell lines. Genomic alterations in SMAD4 were characterised by fluorescence in situ hybridisation, methylation specific PCR, and sequencing. Functional integrity of TGF-beta signalling was assessed by characterisation of p21 and proliferation status. Smad4 negative BIC-1 cells were transiently transfected with smad4 and TGF-beta responsiveness evaluated.

RESULTS

smad4 mRNA expression was progressively reduced in the metaplasia-dysplasia-adenocarcinoma sequence (p<0.01). A quarter of AC samples displayed an abnormal Smad4 protein isoform, with no corresponding changes in gene sequence or organisation. Methylation of smad4 has not been described previously but we found promoter methylation in 70% of primary AC samples. In 6/8 oesophageal cell lines, chromosomal rearrangements affected the smad4 locus. Lack of smad4 expression in BIC-1 cells occurred secondary to loss of one copy and extensive deletion of the second allele's promoter region. TGF-beta dependent induction of p21 and downregulation of minichromosome maintenance protein 2 was lost in >80% of BE and AC. TGF-beta failed to inhibit proliferation in 5/8 oesophageal cell lines. In BIC-1, the antiproliferative response was restored following transient transfection of smad4 cDNA.

CONCLUSIONS

In BE carcinogenesis, downregulation of Smad4 occurs due to several different mechanisms, including methylation, deletion, and protein modification. Frequent alterations in TGF-beta signalling lead to a functionally significant impairment of TGF-beta mediated growth suppression.

Comparative genomic hybridization of esophageal adenocarcinoma and squamous cell carcinoma cell lines

We compared whole genomic changes in cell lines generated from esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC). To do so, we investigated chromosomal DNA copy number changes in four EAC cell lines and three ESCC cell lines using comparative genomic hybridization (CGH). Frequent gains of chromosome 5p, 8q, and 20q occurred in both ESCC and EAC cell lines, but gains of 3q, 5q, and 9q were mainly seen in ESCC cell lines; gain of chromosome 10q25-qtel was mainly seen in EAC cell lines. It was noticeable that 18q12 loss existed in 2 EAC and 1 ESCC cell lines in our study. The chromosomal abnormalities common to all of the cell lines may help to identify candidate genes related to both EAC and ESCC. The chromosome aberrations mainly seen in either EAC or ESCC cell lines are in keeping with their known different etiology and may lead to the identification of genes important for disease specific pathogenesis.

Barrett's oesophagus and oesophageal adenocarcinoma: how does acid interfere with cell proliferation and differentiation?

Acid, a principal component of gastro-oesophageal refluxate, may contribute to the development and malignant progression of Barrett's oesophagus. Oesophageal pH monitoring studies have demonstrated that patients with Barrett's oesophagus have severe and chronic acid reflux. However, there is overlap between the amount of acid exposure in patients with oesophagitis compared with patients with Barrett's oesophagus. This suggests that factors other than acid may be important in the aberrant oesophageal cell differentiation process that leads to the development of the metaplastic Barrett's mucosa. The other factors important in the aetiology of Barrett's oesophagus are poorly understood but probably include both genetic and environmental factors.

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.

Barrett metaplasia: reassessment of treatment and follow-up

PURPOSE OF REVIEW

The incidence of esophageal adenocarcinoma continues to rise in the Western world, with a mean 5-year survival of less than 20%. There has therefore been increasing interest in the precursor lesion, Barrett's esophagus. However, adenocarcinoma will not develop in most patients with Barrett's esophagus. This review summarizes the data on the management of Barrett's esophagus that have been published since January 2003.

RECENT FINDINGS

The control of reflux symptoms significantly improves quality of life, and surgical antireflux therapy may gradually cause regression of the Barrett segment compared with proton pump inhibitor therapy. The data substantiate the claim that the cancer risk in Barrett esophagus is lower than had hitherto been suggested. The risk factors for progression include increasing age and length of segment, macroscopic inflammatory changes, loss of heterozygosity over several genetic loci, and increased proliferation status. The extent of high-grade dysplasia may not accurately predict cancer development, and continued surveillance, rather than intervention, for such patients may decrease the chances of curative treatment. Long-term follow-up data are beginning to accumulate for nonsurgical treatment strategies. Chemoprevention trials are under way to evaluate the role of acid suppression and nonsteroidal anti-inflammatory drugs and their derivatives.

SUMMARY

At this time, endoscopic surveillance and surgical management remain the mainstay, but continued research efforts should enable risk stratification and cancer prevention in the future.

Clinical implications of E-cadherin associated hereditary diffuse gastric cancer

Approximately 1-3% of gastric cancers arise as a result of inherited gastric cancer predisposition syndromes. These may be of the diffuse or intestinal type. Linkage analysis has recently implicated E-cadherin mutations in an estimated 25% of families with an autosomal dominant predisposition to diffuse type gastric cancers. This subset of gastric cancer has been termed hereditary diffuse gastric cancer (HDGC).

E-cadherin mutations and hereditary gastric cancer: prevention by resection?

BACKGROUND

A small percentage of gastric cancers (1-3%) arise as a result of clearly identified inherited gastric cancer predisposition syndromes. Recently, linkage analysis has implicated E-cadherin (CDH1) mutations in a subset of dominantly inherited gastric cancers termed hereditary diffuse gastric cancer (HDGC). Heterozygotes with the CDH1 mutation have a 70-80% chance of developing gastric cancer and once patients have invasive, symptomatic disease there is a high associated morbidity and mortality. As a result prophylactic gastrectomy has been advocated for affected family members identified by genetic screening. There are many issues to be considered in order to determine whether prophylactic gastrectomy is the optimal management strategy for these patients.

METHODS

A MEDLINE literature search was performed and combined with our own experience in order to identify relevant background information on hereditary gastric cancer. In particular we extracted information about prophylactic gastrectomy in HDGC patients.

RESULTS

Once the decision has been undertaken to perform genetic testing, the therapeutic options are either endoscopic screening with the aim of identifying an early, curable lesion or prophylactic surgery. Two groups have published their data on prophylactically resected stomachs in asymptomatic patients from affected families. In these series all of the post-gastrectomy specimens had microscopic evidence of diffuse gastric cancer confined within the mucosal layer. These early cancers had not been identified by endoscopic surveillance. Technical issues surrounding the age at which to operate, the best operation to reduce the risk of post-operative complications and the risk of other cancers developing in other organs in these patients are still controversial. Long-term follow-up studies in specialist centres are required to resolve these issues.

CONCLUSIONS

From the limited experience so far the estimated risk reduction of gastric cancer by gastrectomy is significant.

Inflammatory gradient in Barrett's oesophagus: implications for disease complications

INTRODUCTION

Barrett's oesophageal epithelium (BE) is clinically important due to the associated inflammatory and malignant complications which are unevenly distributed throughout the BE segment. As the immunoregulatory environment may influence disease manifestations, we analysed the inflammatory and cytokine responses throughout the BE mucosa. We then investigated whether the inflammatory gradient is related to the distribution of metaplastic cell subtypes, epithelial exposure to the components of refluxate, or squamocolumnar cell interactions.

METHODS

Fifty consecutive patients with long segment BE were recruited. The segmental degree of endoscopic and histopathological inflammation was graded, and expression of interleukin (IL)-1 beta, IL-8, IL-4, and IL-10 were determined by ELISA following organ culture with or without addition of acid or bile salts. Mucin staining and IL-10 immunohistochemistry were performed. The effect of squamocolumnar interactions on cytokine expression were analysed using cocultures of squamous (OE-21) and BE (TE7) carcinoma cell lines.

RESULTS

There was a histopathological inflammatory gradient in BE. Inflammation was maximal at the new squamocolumnar junction with > or = 2-fold increase in proinflammatory IL-8 and IL-1 beta expression. The proximal proinflammatory response could not be explained by the distribution of metaplastic subtypes. Pulsatile exposure of BE to acid and bile, as well as juxtaposition of BE to squamous epithelial cells in culture, increased expression of IL-1 beta. In contrast, inflammation was minimal distally with a significant increase in anti-inflammatory IL-10 expression and 4/6 cancers occurred distally.

CONCLUSIONS

Specific cytokine responses may contribute to the localisation of inflammatory and malignant complications within BE.

Diversity in the oesophageal phenotypic response to gastro-oesophageal reflux: immunological determinants

BACKGROUND AND AIMS

Approximately 10% of adults experience gastro-oesophageal reflux symptoms with a variable oesophageal response. A total of 60% have no endoscopic abnormality, 30% have oesophagitis, and 10% have Barrett's oesophagus. We investigated whether the inflammatory cell infiltrate and cytokine profiles of these clinical phenotypes merely vary in severity or are fundamentally different.

METHODS

Patients with reflux symptoms and a normal oesophagus (n=18), oesophagitis (n=26), and Barrett's oesophagus (n=22 newly diagnosed, n=28 surveillance) were recruited. Endoscopic and histopathological degrees of inflammation were scored. Cytokine expression was determined by competitive reverse transcriptase-polymerase chain reaction and immunohistochemistry.

RESULTS

In oesophagitis, endoscopic and histopathological grades of inflammation correlated highly. mRNA expression of proinflammatory interleukin (IL)-1beta, IL-8, and interferon gamma (IFN-gamma) were increased 3-10-fold compared with non-inflamed squamous or Barrett's oesophageal samples. There was a modest increase in anti-inflammatory IL-10 but no increase in IL-4. In Barrett's oesophagus, 29/50 had no endoscopic evidence of inflammation and histopathological inflammation was mild in 17/50 and moderate in 24/50, independent of acid suppressants. Expression of IL-1beta, IL-8, and IFN-gamma was similar to non-inflamed squamous mucosa. IL-10 was increased 1.6-fold similar to oesophagitis. IL-4 was increased fourfold, with 100-fold increase in IL-4/T cell receptor expression, compared with squamous oesophagus or oesophagitis.

CONCLUSIONS

Barrett's oesophagus is characterised by a distinct Th-2 predominant cytokine profile compared with the proinflammatory nature of oesophagitis. The specific oesophageal immune responses may influence disease development and progression.

Women in hospital medicine: career choices and opportunities

A significant number of women now enter hospital medicine. However, many do not make the expected progression within the medical specialties. The Royal College of Physicians set up a working party to examine and collect evidence on the career choices and progression of women in the hospital medical specialties under its remit and published a report of this evidence. This article outlines the findings of the report and the implications for hospital medicine.

Upright versus supine reflux in gastroesophageal reflux disease

BACKGROUND

Postural measures are early recommendations in the management of heartburn, and are aimed at preventing acid reflux through an incompetent lower esophageal sphincter (LES). However, LES incompetence is found in only a minority of patients, and transient LES relaxations, primarily in the upright position, are currently recognized as the main pathophysiological abnormality in gastroesophageal reflux disease (GERD). We investigated the importance of supine acid reflux in patients with GERD.

METHODS

Upon review of their clinical, manometric, pH monitoring and endoscopic characteristics, 85 patients with reflux symptoms were classified into three groups: Group A (n=22), consisting of symptomatic patients without esophagitis or pathological reflux; group B (n=38), symptomatic patients with reflux but no endoscopic esophagitis; and group C (n=25), symptomatic patients with both ulcerative or complicated esophagitis and pathological reflux.

RESULTS

All groups were similar in age distribution. Groups B and C had a higher prevalence of hiatal hernia and reflux symptoms. Manometry revealed similar LES pressures in groups A and B, but lower LES pressure in group C (P < 0.005). In groups A and B, supine reflux, in terms of percentage of time with pH < 4, was less pronounced than upright reflux (P < 0.0001). In contrast, group C supine reflux was as pronounced as the upright reflux.

CONCLUSIONS

The majority of patients reflux in the upright position. Only patients with complicated esophagitis have significant bipositional acid reflux. These findings suggest that unless the patient has severe reflux disease, postural measures may not be indicated.

Rigorous surveillance protocol increases detection of curable cancers associated with Barrett's esophagus

Esophageal adenocarcinoma is increasing in incidence and has a high mortality unless detected early. Barrett's esophagus is the only known risk factor for this cancer; however, whether endoscopic surveillance reduces morbidity and mortality is controversial. Endoscopic cancer surveillance programes for Barrett's esophagus are not routinely practiced in the UK, and this is the first study to examine whether a rigorous surveillance protocol increases the detection rate of early oesophageal cancer. All patients with a diagnosis of Barrett's esophagus or associated adenocarcinoma attending Havering Hospitals NHS Trust between 1992 and 1998 were included. A retrospective analysis was made of patients undergoing informal surveillance (96 patients, 1992-1997) and a prospective analysis was conducted following the implementation of a rigorous protocol (108 patients, 1997-1998). Over the same time periods Barrett's associated cancers diagnosed in patients not undergoing surveillance were analyzed (262 patients 1992-1997, 98 patients 1997-1998). From 1992 to 1997, one case of high-grade dysplasia was detected (N = 96, 1%). From 1997 to 1998, two cancers and three high-grade dysplasias were detected during rigorous surveillance (N = 108, 4.6%). Three of these patients have had curative esophagectomies (one high-grade dysplasia and two T1,N0,M0 tumors). In 1992-1997, 10 patients were found to have cancer in previously undiagnosed Barrett's esophagus (N = 262, 3.8%). Of 3/10 cancers treated surgically, one patient had a curative procedure (T1,N0,M0). In 1997-1998, nine patients were found to have de novo Barrett's esophagus cancer (N = 88, 10.2%) and three had curative resections (T1,N0,M0). Two of the patients with T1 lesions had no endoscopic evidence of cancer but were detected as a result of the multiple biopsy protocol. In conclusion, a rigorous biopsy protocol increases the detection of early cancer in Barrett's esophagus.

Novel adaptation of brush cytology technique for short-term primary culture of squamous and Barrett's esophageal cells

BACKGROUND

Esophageal disease research is impeded by a paucity of nonmalignant cell lines. Furthermore, culture of primary esophageal cells is difficult because of a lack of cell adhesion and contamination. The aim of this study was to develop a short-term culture method to facilitate cell physiologic studies by using primary esophageal cells.

METHODS

By using a cytology brush, squamous and Barrett's epithelial cells were obtained from the esophagus of patients undergoing upper endoscopy. Cells were brushed onto chamber slides and allowed to adhere to the surface. Primary culture media was then added and cells were maintained at 37 degrees C for up to 72 hours. Cell yield and viability were calculated after trypan blue staining. For cell physiologic studies, cells were loaded with pH-sensitive dye BCECF-AM and intracellular pH measured on a dual excitation fluorescence microscope after an ammonium chloride prepulse. At the end of the physiologic experiments, cells were fixed in methanol and acetone and the cell type was verified with cytokeratin immunocytochemistry.

RESULTS

Viable human esophageal cells were maintained in culture for up to 72 hours. The cells extruded trypan blue, and BCECF-AM was cleaved to BCECF by an intact cell membrane and permitted intracellular pH measurements. The epithelial cell origin of the cells was confirmed by cytokeratin staining. There was no contamination over the culture period and no overgrowth by lymphocytes or fibroblasts.

CONCLUSIONS

This novel adaptation of brush cytology technique enables short-term culture of esophageal cells for in vitro studies. This rapid, simple primary culture technique is suitable for endoscopy and does not require the immediate, time-consuming laboratory techniques.

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

Barrett's oesophagus, a significant complication of gastro-oesophageal reflux disease (GERD), is the single most important risk factor for oesophageal adenocarcinoma. The strong association between Barrett's oesophagus and chronic GERD suggests that abnormal oesophageal acid exposure plays an important role in this condition. The progression of Barrett's oesophagus from specialized intestinal metaplasia to dysplasia and finally invasive carcinoma is incompletely understood, but increased and disordered proliferation is a key cellular event. In ex vivo organ culture experiments, cell proliferation is increased after exposure to short pulses of acid, whilst proliferation is reduced in Barrett's oesophagus specimens taken from patients with oesophageal acid exposure normalized by antisecretory therapy. In long-term clinical studies, consistent and profound intra-oesophageal acid suppression with proton pump inhibitors decreases cell proliferation and increases differentiation in Barrett's oesophagus, but the clinical importance of such favourable effects on these surrogate markers is not clear. In clinical practice, proton pump inhibitors relieve symptoms and induce partial regression to squamous epithelium, but abnormal oesophageal acid exposure and the risk for dysplasia or adenocarcinoma persist in many patients. The ability of proton pump inhibitors to suppress acid profoundly and consistently may be critical in the long-term management of Barrett's oesophagus.

Differentiation and proliferation in Barrett's esophagus and the effects of acid suppression

BACKGROUND & AIMS

Maintenance of normal epithelial differentiation and proliferation is an important goal in cancer chemoprevention. Because acid has a dynamic effect on cell proliferation/differentiation of Barrett's esophagus (BE) ex vivo, we investigated the relationship between differentiation, proliferation, and dysplasia in BE biopsy specimens and explored the role of normalization of intraesophageal pH in altering the BE phenotype.

METHODS

Endoscopic biopsy specimens of BE (with or without dysplasia) were analyzed for (1) villin, a differentiation marker, by immunoblotting; (2) proliferating cell nuclear antigen (PCNA), a proliferation marker, by immunohistochemistry; and (3) dysplasia by histology before and after 6 months of normalization of intraesophageal pH (confirmed by 24-hour pH monitoring) with lansoprazole.

RESULTS

At baseline, there was a negative correlation (r = -0.79) between villin and PCNA expression. Six months later, PCNA expression decreased and villin expression increased (P < 0.001) in 24 patients whose intraesophageal pH normalized. Fifteen patients had persistently pathological intraesophageal acid reflux and no change in villin or PCNA expression. There were no differences in the occurrence of dysplasia after 6 months in either group.

CONCLUSIONS

In BE, there is an inverse relationship between villin and PCNA. In turn, dysplasia is unrelated to villin expression and well correlated with PCNA expression. Complete symptom eradication with lansoprazole does not guarantee normalization of intraesophageal pH profile in BE patients. Effective intraesophageal acid suppression favors differentiation and decreases proliferation. The intriguing possibility that acid suppression can be used to prevent dysplasia remains to be explored.

Altered sodium-hydrogen exchange activity is a mechanism for acid-induced hyperproliferation in Barrett's esophagus

Acid produces a dynamic effect on the cell phenotype of Barrett's esophagus (BE) ex vivo. An acid pulse induces hyperproliferation, whereas continuous acid exposure promotes differentiation. To examine the mechanism for acid pulse-induced hyperproliferation, we studied the Na+/H+ exchanger (NHE), which plays a role in the control of intracellular pH and cell proliferation. NHE was inhibited pharmacologically in endoscopic BE biopsies using amiloride analogs. Cell proliferation was assessed after pulsed or continuous acid exposure using tritiated thymidine incorporation assays and immunohistochemical analysis of proliferating cell nuclear antigen expression. The NHE-dependent intracellular pH response to an acid pulse was examined by pH-sensitive microfluorimetry using a Barrett's adenocarcinoma cell line TE7. NHE inhibition significantly reduced the hyperproliferative acid-pulse effect. Furthermore, the acid-pulse activation of NHE occurred via increased transporter activity (22Na uptake) without any change in NHE-1 protein levels. Inhibition of protein kinase C (PKC), an NHE activator, also reduced the hyperproliferative response. The response of TE7 cells to an acid pulse was similar to that of BE biopsies in terms of cell proliferation and NHE and PKC dependence. Acid-pulse exposure of TE7 cells resulted in intracellular acidification followed by reneutralization to an intracellular pH greater than preacidosis values. We conclude that NHE may mediate the hyperproliferative response of BE to an acid pulse via changes in intracellular pH.

Recent developments in the molecular characterization of Barrett's esophagus

Barrett's esophagus, or specialized intestinal metaplasia, is a common condition associated with gastroesophageal reflux and an increased risk for adenocarcinoma of the esophagus and gastric cardia. Currently, clinical surveillance for early detection of adenocarcinoma relies on the histopathological assessment of dysplasia. In this review we present data from the published literature, and combine this with results from our own research, to address what is currently known about the environmental factors and the molecular changes thought to be important in the pathogenesis of Barrett's esophagus. The most important and well-characterized molecular changes, preceding the development of dysplasia, are alterations in the p53 and erbB-2 genes and aneuploidy. These molecular changes, as well as environmental influences, such as the quality and quantity of gastroduodenal refluxate, may result in abnormal cell proliferation which in turn promotes further genetic abnormalities and deregulation of cell growth. The identification of molecular changes, in the context of predisposing environmental factors, will enhance our understanding of the malignant progression of Barrett's esophagus leading to more effective surveillance and treatment.

Acid modulation of HT29 cell growth and differentiation. An in vitro model for Barrett's esophagus

Cell proliferation and differentiation are influenced by environmental factors, including the extracellular pH. We recently showed, using an ex vivo organ culture system of human mucosal Barrett's esophageal biopsies, that acid has a highly variable effect on cell proliferation and differentiation depending on the pattern of acid exposure. Study of the mechanisms underlying these dynamic effects of acid on this premalignant intestinal-like epithelium is hampered by lack of an immortalized cell line. We therefore investigated the effect of acid exposure on the human colonic carcinoma cell line HT29, chosen because of its intestinal cell derivation and its ability to differentiate in vitro. HT29 cells exposed to pH 5 medium either continuously (up to 3 weeks), or as a short (1 hour) pulse, were compared with cells cultured at pH 7.4. Villin expression was induced only by long term acid exposure, and correlated with the development of differentiated polarized cells that contain a brush border and microvillus inclusions. Chronic acid exposure arrested cell proliferation, whereas a 1 hour acid-pulse enhanced cell proliferation, as determined by [3H]thymidine incorporation assays and proliferating cell nuclear antigen expression. Serum starvation attenuated the hyperproliferative effect of an acid-pulse. In addition, the doubling time of at least the first cell cycle after an acid-pulse was shortened. The Na/H exchanger is likely to play a role since the hyperproliferative acid-induced response was blocked by amiloride; and the activity of the exchanger was increased at acidic pH as determined by 22Na uptake. These results support a role for extracellular pH on cell proliferation and differentiation of HT29 cells. Furthermore, these findings parallel the dynamic effects of acid on Barrett's esophagus, and suggest that HT29 cells could serve as an in vitro model for studying the mechanism of acid modulation in Barrett's esophagus.

Esophageal manifestations of rheumatic disorders

This study was performed to review information on functional and anatomic esophageal manifestations in patients with rheumatic disorders and to outline their pathogenesis, diagnosis, and treatment in light of the current medical, endoscopic, and surgical advances. A MEDLINE search of English-language articles published between 1985 and 1995, reviews of the bibliographies of textbooks, and a manual search of the reference lists of relevant articles formed the data sources, all combined with our own clinical experience. Primary research and review articles addressing the pathogenesis, diagnosis, treatment, prognosis, and complications of esophageal disease occurring in a rheumatic context were selected, with emphasis on recently developed medical, endoscopic, and surgical methods for diagnosis and management. Study design and quality were assessed, with particular attention paid to methods and aims. Relevant data on frequency, clinical presentation, and relationship to underlying rheumatic disorder, prognosis, and clinical management were analyzed. Esophageal manifestations are common in patients with rheumatic diseases and range in nature and severity from functional myopathic or neuropathic esophageal dysmotility to extrinsic lumenal compression and esophageal mucosal damage from gastroesophageal acid reflux or opportunistic infection. The primary symptoms of heartburn, dysphagia, odynophagia, chest pain, and bleeding may be directly related to the underlying rheumatic disease or may be the unwanted effects of therapy with nonsteroidal antiinflammatory drugs, immunosuppressants, or disease-modifying agents. Easily over-looked in the context of a multisystemic disease, these esophageal symptoms may be amenable to simple treatments, but frequently require a thorough assessment by modern, sophisticated diagnostic tools. In many instances, functional and structural involvement of the esophagus in patients with rheumatic disorders requires a high index of suspicion for an early diagnosis, correct assessment, intensive surveillance, and aggressive therapy to avoid end-organ damage and decline in quality of life. Significant recent advances in the understanding of esophageal pathophysiology, the development of diagnostic techniques, progress in diagnostic and therapeutic endoscopy, and minimally invasive surgery allow early detection and effective long-term therapy for esophageal dysfunction associated with rheumatic diseases.

Testosterone concentrations in men on chronic glucocorticosteroid therapy

To determine whether free (or active) testosterone concentrations are reduced in men receiving glucocorticosteroids for chronic inflammatory diseases, 17 men (mean age 55.5 years) receiving a mean daily dose of 16.3 mg prednisolone, and 13 control patients (mean age 52.2 years) receiving no prednisolone, were studied. Serum testosterone and the testosterone/sex hormone binding globulin (SHBG) ratio were measured. The testosterone/SHBG ratio (a measure of free (active) testosterone) was significantly reduced in patients treated with prednisolone (p = 0.026), thus showing that glucocorticosteroids reduce free testosterone in male patients. This may be an important cause of glucocorticosteroid-induced osteoporosis, and suggests an additional approach to bone prophylaxis and treatment.

Dynamic effects of acid on Barrett's esophagus. An ex vivo proliferation and differentiation model

Barrett's esophagus (BE), or specialized intestinal metaplasia, is a premalignant heterogeneous epithelium associated with reflux and an increased risk for adenocarcinoma. Since acid is a major component of refluxate, we investigated its effects ex vivo on cell differentiation as determined by villin expression; and on cell proliferation, as determined by tritiated thymidine incorporation and proliferating cell nuclear antigen expression. To mimic known physiological conditions, endoscopic biopsies of normal esophagus, BE, and duodenum were exposed, in organ culture, to acidified media (pH 3-5) either continuously, or as a 1-h pulse and compared with exposure to pH 7.4 for up to 24 h. Before culture, villin expression was noted in 25% of BE samples, and increased after 6 or 24 h of continuous acid to 50% or 83% of BE samples, respectively. Increased villin expression correlated with ultrastructural maturation of the brush border. In contrast, an acid-pulse followed by culture at pH 7.4, did not alter villin expression in BE. Moreover, continuous acid exposure blocked cell proliferation in BE, whereas, an acid-pulse enhanced cell proliferation, as compared to pH 7.4. Based on our ex vivo findings, we propose a model in which the diverse patterns of acid exposure in vivo may contribute to the observed heterogeneity and unpredictable progression to neoplasia of BE.