Genomic analysis of Barrett's esophagus after ablative therapy: persistence of genetic alterations at tumor suppressor loci

Shorter time to achieve endoscopic eradication is not associated with improved long-term outcomes in Barrett's esophagus

Quality indicators have been proposed for endoscopic eradication therapy of Barrett's esophagus (BE). One such measure suggests that complete eradication of intestinal metaplasia (CE-IM) should be achieved within 18 months of starting treatment. The aim of this study was to assess whether achievement of CE-IM within 18 months is associated with improved long-term clinical outcomes. This was a retrospective cohort study of BE patients who underwent endoscopic eradication. Time to CE-IM was recorded and categorized as ≤ or > 18 months. The main outcome measures were recurrence of IM and of dysplasia after CE-IM, defined as a single endoscopy without endoscopic evidence of BE or histologic evidence of intestinal metaplasia. Recurrence was analyzed using the Kaplan-Meier method and multivariable Cox proportional hazards modeling. A total of 290 patients were included in the analyses. The baseline histology was high-grade dysplasia or intramucosal carcinoma in 74.2% of patients. CE-IM was achieved in 85.5% of patients, and 54.1% of the cohort achieved CE-IM within 18 months. Achieving CE-IM within 18 months was not associated with reduced risk of recurrence of IM or dysplasia in both unadjusted and adjusted analyses. In this cohort, older age and increased BE length were associated with IM recurrence, and increased hiatal hernia size was associated with dysplasia recurrence. Compared to longer times, achieving CE-IM within 18 months was not associated with a reduced risk of recurrence of IM or dysplasia. Alternative evidence-based quality metrics for endoscopic eradication therapy should be identified.

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.

Changes in gene expression of neo-squamous mucosa after endoscopic treatment for dysplastic Barrett's esophagus and intramucosal adenocarcinoma

BACKGROUND

Endoscopic therapy, including by radiofrequency ablation (RFA) or endoscopic mucosal resection (EMR), is first line treatment for Barrett's esophagus (BE) with high-grade dysplasia (HGD) or intramucosal cancer (IMC) and may be appropriate for some patients with low-grade dysplasia (LGD).

OBJECTIVE

The purpose of this study was to investigate the molecular effects of endotherapy.

METHODS

mRNA expression of 16 genes significantly associated with different BE stages was measured in paired pre-treatment BE tissues and post-treatment neo-squamous biopsies from 36 patients treated by RFA (19 patients, 3 IMC, 4 HGD, 12 LGD) or EMR (17 patients, 4 IMC, 13 HGD). EMR was performed prior to RFA in eight patients. Normal squamous esophageal tissues were from 20 control individuals.

RESULTS

Endoscopic therapy resulted in significant change towards the normal squamous expression profile for all genes. The neo-squamous expression profile was significantly different to the normal control profile for 11 of 16 genes.

CONCLUSION

Endotherapy results in marked changes in mRNA expression, with replacement of the disordered BE dysplasia or IMC profile with a more "normal" profile. The neo-squamous mucosa was significantly different to the normal control squamous mucosa for most genes. The significance of this finding is uncertain but it may support continued endoscopic surveillance after successful endotherapy.

Clonal selection and persistence in dysplastic Barrett's esophagus and intramucosal cancers after failed radiofrequency ablation

OBJECTIVES

Radiofrequency ablation (RFA) is used to successfully eliminate Barrett's esophagus (BE)-related dysplasia or intramucosal carcinoma and aims to cause reversion to squamous epithelium. However, in 20% of cases RFA fails to return the epithelium to squamous phenotype. Follow-up studies show a similar dysplasia recurrence rate. We hypothesize that failed RFA is due to clonally mutated epithelial populations harbored in RFA-privileged sites and that RFA can select for the mutant clonal expansion.

METHODS

A longitudinal case series of 19 patients with BE and high-grade dysplasia or intramucosal carcinoma were studied. DNA was extracted from individual Barrett's glands, deep esophageal glands within mucosal resections and biopsy specimens before and after RFA. Mutations were identified by targeted sequencing of genes commonly mutated in Barrett's adenocarcinoma.

RESULTS

Five patients demonstrated persistent post-RFA pathology with persistent mutations, sometimes detected in deep esophageal glands or neighboring squamous epithelium after several rounds of RFA preceded by mucosal resection. Recurrence of pathology in three other patients was characterized by de novo mutations.

CONCLUSIONS

Protumorigenic mutations can be found in post-ablation squamous mucosa as well as in mutant deep esophageal glands; both are associated with dysplasia recurrence. Following RFA, non-dysplastic Barrett's epithelium can contain mutant clones that are found in a subsequent adenocarcinoma. Ablation may also drive the clonal expansion of pre-existing clones after a "bottleneck" created by the RFA. Overall, recurrence of dysplasia post RFA reflects the multicentric origins of Barrett's clones and highlights the role of clonal selection in carcinogenesis.

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.

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.

p16 gene mutations in Barrett's esophagus in gastric metaplasia - intestinal metaplasia - dysplasia - adenocarcinoma sequence

PURPOSE

Barrett's associated esophageal adenocarcinoma (ADC) is one of the malignancies of most rapidly increasing incidence. The aim of the study was to assess p16 tumor suppressor gene alterations in the ADC premalignant conditions.

MATERIAL & METHODS

In the present study two p16 gene mutations (A148T and I49S) analysis with PCR- RFLP method have been performed in oesophageal biopsy specimen in 33 patients with Barrett's gastric metaplasia (GM), 27 - with Barrett's intestinal metaplasia (IM), 8 - with dysplasia and 11 - with ADC.

RESULTS

We have detected the I49S mutation in 12% (4/33) patients with GM, 18% (5/27) with IM, 50% - with dysplasia (4/8) and in 27% (3/11) - with ADC. The A148T mutation were found in 3% (1/33) patients with GM, 22% (6/27) - IM, 25% (2/8) - dysplasia and 27% patients with ADC (3/11). The frequency of the A148S mutation was rising in GM - IM - dysplasia - ADC sequence and was significantly lower in GM compared to all other grades taken together (p=0.0256). The frequency of the I49S mutation was rising in GM - IM - dysplasia sequence, to drop in ADC cases. There were no significant differences in frequency of the I49S mutation between studied groups.

CONCLUSIONS

These findings are consistent with the hypothesis on the role of the p16 mutations in early phase of Barrett's epithelium progression to ADC. The presence of p16 mutations in esophageal metaplastic columnar epithelium without goblet cells suggest that this pathology may have malignancy potential.

Effectiveness, safety, and cost-effectiveness of photodynamic therapy in Barrett's esophagus: a systematic review

Barrett's esophagus, the management of which remains controversial, is the precursor condition to esophageal adenocarcinoma. A number of endoscopic treatments have been designed as an alternative to surgical resection for patients with high-grade dysplasia. One of these, photodynamic therapy, involves the light activation of a photosensitizer that causes local tissue destruction via oxidation reactions. The present work reviews the effectiveness, safety, and cost-effectiveness of this treatment. A systematic review of the literature recorded in the Medline, Embase, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Database, and the National Health Service Economic Evaluation Database was undertaken. Articles reporting randomized clinical trials of photodynamic therapy for the treatment of Barrett's esophagus, and economic assessments of the procedure, were selected. The quality of the articles was checked. Twelve articles were included in this review: eight randomized, controlled clinical trials and four economic assessments. The clinical trials suffered from methodological limitations, but the economic assessments were considered to be good quality. Photodynamic therapy is effective for the ablation of dysplasia in Barrett's esophagus, although the frequency of adverse events is quite high. The procedure is presented as a cost-effective alternative to intense endoscopic monitoring and esophagectomy. However, the evidence regarding its effectiveness in reducing the number of patients who go on to develop cancer is only incipient. Rigorous, controlled studies with longer follow-up times, in which photodynamic therapy is compared with surgical resection and other endoscopic techniques, are needed.

Endoscopic therapy using radiofrequency ablation for esophageal dysplasia and carcinoma in Barrett's esophagus

Radiofrequency ablation (RFA) is a novel and promising treatment modality for treatment of Barrett's esophagus (BE) with high-grade dysplasia or early carcinoma. RFA can be used as a single-modality therapy for flat-type mucosa or as a supplementary therapy after endoscopic resection of visible abnormalities. The treatment protocol consists of initial circumferential ablation using a balloon-based electrode, followed by focal ablation of residual Barrett's epithelium. RFA is less frequently associated with stenosis and buried glandular mucosa as are other ablation techniques and has shown to be safe and effective in the treatment of patients with BE and early neoplasia. In this article, the technical background, current clinical experience, and future prospects of RFA are evaluated.

A cost-utility analysis of ablative therapy for Barrett's esophagus

BACKGROUND & AIMS

Recommendations for patients with Barrett's esophagus (BE) include endoscopic surveillance with esophagectomy for early-stage cancer, although new technologies to ablate dysplasia and metaplasia are available. This study compares the cost utility of ablation with that of endoscopic surveillance strategies.

METHODS

A decision analysis model was created to examine a population of patients with BE (mean age 50), with separate analyses for patients with no dysplasia, low-grade dysplasia (LGD), or high-grade dysplasia (HGD). Strategies compared were no endoscopic surveillance; endoscopic surveillance with ablation for incident dysplasia; immediate ablation followed by endoscopic surveillance in all patients or limited to patients in whom metaplasia persisted; and esophagectomy. Ablation modalities modeled included radiofrequency, argon plasma coagulation, multipolar electrocoagulation, and photodynamic therapy.

RESULTS

Endoscopic ablation for patients with HGD could increase life expectancy by 3 quality-adjusted years at an incremental cost of <$6,000 compared with no intervention. Patients with LGD or no dysplasia can also be optimally managed with ablation, but continued surveillance after eradication of metaplasia is expensive. If ablation permanently eradicates >or=28% of LGD or 40% of nondysplastic metaplasia, ablation would be preferred to surveillance.

CONCLUSIONS

Endoscopic ablation could be the preferred strategy for managing patients with BE with HGD. Ablation might also be preferred in subjects with LGD or no dysplasia, but the cost effectiveness depends on the long-term effectiveness of ablation and whether surveillance endoscopy can be discontinued after successful ablation. As further postablation data become available, the optimal management strategy will be clarified.

DNA copy number alterations correlate with survival of esophageal adenocarcinoma patients

Despite recent advances in surgical and multidisciplinary treatment, prognosis for patients with esophageal adenocarcinoma remains poor, and the low prognostic significance of pTNM staging suggests that additional parameters are needed. To identify genomic abnormalities characteristic of esophageal adenocarcinoma, a panel of 33 samples obtained at surgery from previously untreated patients were analyzed by muliplex ligation-dependent probe amplification technique. We detected frequent gains of 6p, 8q, 13q, 17q, 20q, and losses of 4q, 5q, 15q, and 18q. When DNA copy number changes were correlated to clinicopathological features of patients no association was found between the number of chromosomal aberrations and gender, age, tumor grade or pTNM staging. However, interestingly, a significant correlation between patient survival and total number of chromosomal aberrations was found when esophageal adenocarcinoma cases were stratified according to the median of survival (20 months) (P=0.002) or the median of aberrations (12 aberrations) (P=0.014). Evaluation of the distribution of gains and losses at the level of single chromosomes indicated that gains on chromosomes 5, 6, 8, 11, 20 and losses on chromosomes 1, 3, 5, 11, and 18 were significantly different in the two survival groups. Furthermore, when single gene imbalances were analyzed in further details, we found that besides alterations that involve genes shared by both survival groups, a few genes (KIAA0170, EMS1, ABCC4, F3, and MIF) were altered only in samples from patients with poor survival. Thus, we established a good correlation between the total number of chromosomal alterations and survival, suggesting that the estimation of total imbalances might represent an additional indicator of disease outcome. In addition, the finding of alterations specific for the more aggressive esophageal adenocarcinoma subset might represent promising biomarkers to increase the accuracy of clinical outcome prediction.

Correlation of histology with biomarker status after photodynamic therapy in Barrett esophagus

BACKGROUND

Currently, histology is used as the endpoint to define success with photodynamic therapy (PDT) in patients with high-grade dysplasia (HGD). Recurrences despite 'successful' ablation are common. The role of biomarkers in assessing response to PDT remains undefined. The objectives of the current study were 1) to assess biomarkers in a prospective cohort of patients with HGD/mucosal cancer before and after PDT and 2) to correlate biomarker status after PDT with histology.

METHODS

Patients who underwent PDT for HGD/mucosal cancer were studied prospectively. All patients underwent esophagogastroduodenoscopy, 4-quadrant biopsies every centimeter, endoscopic mucosal resection of visible nodules, and endoscopic ultrasound. Cytology samples were obtained by using standard cytology brushes. Biomarkers were assessed by using fluorescence in situ hybridization (FISH). The biomarkers that were assessed included loss of 9p21 (site of the p16 gene) and 17p13.1 (site of the p53 gene) loci; gains of the 8q24(c-myc), 17q (HER2-neu), and 20q13 loci; and multiple gains. Patients received PDT 48 hours after the administration of sodium porfimer. Demographic and clinical variables were collected prospectively. Patients were followed with endoscopy and repeat cytology for biomarkers. The McNemar test was used to compare biomarker proportions before and after PDT.

RESULTS

Thirty-one patients were studied. The median patient age was 66 years (interquartile range [IQR], 56-73 years), and 28 patients (88%) were men. The mean Barrett segment length was 5 cm (standard error of the mean, 0.5 cm). Post-PDT biomarkers were obtained after a median duration of 9 months (IQR, 3-12 months). There was a statistically significant decrease in the proportion of several biomarkers assessed after PDT. Six patients without HGD after PDT still had positive FISH results for 1 or more biomarkers: of these, 2 patients (33%) developed recurrent HGD.

CONCLUSIONS

In this initial study, histologic downgrading of dysplasia after PDT was associated with the loss of biomarkers that have been associated with progression of neoplasia in Barrett esophagus. Patients with persistently positive biomarkers appeared to be at a higher risk of recurrent HGD. These findings should be confirmed in a larger study.

Stepwise radical endoscopic resection of the complete Barrett's esophagus with early neoplasia successfully eradicates pre-existing genetic abnormalities

OBJECTIVES

Malignant transformation of Barrett's mucosa is associated with the accumulation of genetic alterations. Stepwise radical endoscopic resection of the Barrett's segment with early neoplasia is a promising new treatment resulting in complete re-epithelialization of the esophagus with neosquamous epithelium. It is unknown whether radical resection also eradicates genetic abnormalities. The aim of this study was to prospectively evaluate whether genetic abnormalities as found in the Barrett's segment before radical resection are effectively eradicated and absent in the neosquamous epithelium.

METHODS

Nine patients with early neoplasia who successfully underwent radical resection were included. Immunohistochemistry (IHC) was performed to assess p53 protein overexpression. DNA fluorescent in-situ hybridization was (DNA-FISH) performed for evaluation of numerical abnormalities of chromosomes 1 and 9, and losses of p16 and p53. Immunohistochemistry and DNA-FISH were performed on endoscopic resection specimens of the neoplasia and on follow-up biopsies of the neosquamous epithelium.

RESULTS

DNA-FISH and IHC showed alterations in the pretreatment samples of all patients. All showed aneusomy of chromosome 1 and 9. Loss of p16 and p53 were seen in 6 and 8 patients. IHC showed intense p53 nuclear staining in seven patients. Post-treatment biopsies showed neosquamous epithelium with a normal diploid signal count for all DNA-FISH probes and normal IHC stainings in all patients.

CONCLUSIONS

Radical resection of Barrett's esophagus with early neoplasia successfully eradicates pre-existing genetic abnormalities and results in neosquamous epithelium without these genetic abnormalities.

Doppler optical coherence tomography monitoring of microvascular tissue response during photodynamic therapy in an animal model of Barrett's esophagus

BACKGROUND

Doppler optical coherence tomography (DOCT) is an imaging modality that allows assessment of the microvascular response during photodynamic therapy (PDT) and may be a powerful tool for treatment monitoring/optimization in conditions such as Barrett's esophagus (BE).

OBJECTIVE

To assess the technical feasibility of catheter-based intraluminal DOCT for monitoring the microvascular response during endoluminal PDT in an animal model of BE.

DESIGN

Thirteen female Sprague-Dawley rats underwent esophagojejunostomy to induce enteroesophageal reflux for 35 to 42 weeks and the formation of Barrett's mucosa. Of these, 9 received PDT by using the photosensitizer Photofrin (12.5 mg/kg intravenous), followed by 635-nm intraluminal light irradiation 24 hours after drug administration. The remaining 4 surgical rats underwent light irradiation without Photofrin (controls). Another group of 5 normal rats, without esophagojejunostomy, also received PDT. DOCT imaging of the esophagus by using a catheter-based probe (1.3-mm diameter) was performed before, during, and after light irradiation in all rats.

RESULTS

Distinct microstructural differences between normal squamous esophagus, BE, and the transition zone between the 2 tissues were observed on DOCT images. Similar submucosal microcirculatory effects (47%-73% vascular shutdown) were observed during PDT of normal esophagus and surgically induced BE. Controls displayed no significant microvascular changes.

CONCLUSIONS

No apparent difference was observed in the PDT-induced vascular response between normal rat esophagus and the BE rat model. Real-time monitoring of PDT-induced vascular changes by DOCT may be beneficial in optimizing PDT dosimetry in patients undergoing this therapy for BE and other conditions.

Increasing genomic instability during premalignant neoplastic progression revealed through high resolution array-CGH

Chromosomal instability is regarded as an underlying mechanism of neoplastic progression, integral to the clonal selection and evolution that leads to cancer. We evaluated chromosomal instability in premalignant Barrett's esophagus tissue using high resolution Affymetrix mapping 100K SNP arrays as patients progressed through three molecular stages of disease-CDKN2A(LOH) only, CDKN2A(LOH)/TP53(LOH), and CDKN2A(LOH)/TP53(LOH) with aneuploidy. Within individuals over time, we observed increases in both numbers and sizes of regions of LOH or copy number change. In the earliest CDKN2A(LOH) only samples, we detected few regions with both copy change and LOH, whereas copy loss and LOH were highly correlated in more advanced samples. These data indicate that genomic instability increases in severity and changes character during neoplastic progression. In addition, distinct patterns of clonal evolution could be discerned within a segment of Barrett's esophagus. Overall, this study illustrates that pre-malignant disease can be associated with extensive instability and clonal dynamics that evolve from an initial stage characterized by small recombination-based alterations to one with larger copy change events likely associated with mitotic instability.

Endoscopic therapy of dysplasia and early-stage cancers of the esophagus

Endoscopic treatments have become a viable alternative for some patients with early-stage esophageal neoplasia. Although esophagectomy remains the standard of care for high-grade dysplasia and superficial cancers, surgical morbidity and mortality may deter patients who are medically unfit or reluctant to undergo surgery. Photodynamic therapy (PDT) and endoscopic mucosal resection (EMR) are the best-studied nonsurgical approaches at present. PDT has been reported to eradicate high-grade dysplasia (HGD) and early Barrett's cancers at rates ranging from 75% to 100% and 17% to 100%, respectively, and a recent randomized controlled trial confirmed that PDT may prevent progression of HGD to cancer. Complete remission rates greater than 90% have also been reported with EMR and other mucosa-ablating interventions, although recurrence rates necessitate close endoscopic surveillance and retreatment in some patients. In addition to PDT and EMR, several emerging endoscopic treatment options for superficial esophageal neoplasia may provide attractive alternatives to surgery.

Barrett's oesophagus?a pathologist's view

Barrett's oesophagus, a precancerous condition for oesophageal adenocarcinoma, detected on endoscopy and confirmed on histology, shows intestinal metaplasia of the lower oesophagus. The significance of microscopic foci of intestinal metaplasia at the gastro-oesophageal junction, corresponding either to so-called 'ultrashort' segment Barrett's oesophagus, or to carditis with intestinal metaplasia, is still a matter of debate. The surveillance of patients with Barrett's oesophagus is still based on systematic biopsy sampling of Barrett's mucosa on endoscopy, looking for dysplasia. Although well-established classifications of dysplasia are now used by most pathologists, there remain numerous problems with this subjective marker (sampling, diagnostic reproducibility, natural history, etc). Therefore, many alternative biomarkers have been proposed, but only DNA aneuploidy, proliferation markers and p53 loss of heterozygosity/overexpression have been shown to be of some use at the present time. Some endoscopic improvements already allow a better selection of biopsies, and it may be that in future new technologies will allow 'virtual biopsies'. On the other hand, the role of pathologists now extends to the evaluation of new therapeutic modalities of early neoplastic lesions in Barrett's oesophagus, especially endoscopic mucosal resection.

Pathologic Risk Factors of Adenocarcinoma of the Gastric Cardia and Gastroesophageal Junction

Available evidence supports the existence of two major pathways of neoplastic development in the gastroesophageal region: the Barrett pathway, related to gastroesophageal reflux disease, and the gastric pathway, related to Helicobacter pylori infection. The existence of an independent junctional pathway is questionable, and gastroesophageal junction adenocarcinomas share features of esophageal and gastric adenocarcinomas. It has been impossible to accommodate all data that are provided by different levels and tools of observation in tumors that develop in the gastroesophageal region in a single, coherent classification. That is why the stratification of pathologic risk in such tumors, and their respective precursors, incorporates features from topography, histology, immunohistochemistry, and molecular pathology.

Laser ablation therapies for Barrett's esophagus

The metaplastic change of the normal squamous epithelium of the distal esophagus into a specialized columnar epithelium is known as Barrett's esophagus (BE) and is associated with an increased risk of adenocarcinoma of the esophagus. It is a frequent complication of gastroesophageal reflux disease (GERD) and up to 10% of patients with GERD suffer from BE. The progression to dysplasia increases the risk of cancer development and the annual risk of developing cancer in Barrett's esophagus is estimated to be 0.5% per year. The management of BE with high grade dysplasia (HGD) is controversial. Recent innovations in endoscopic therapy have allowed for the development of multiple endoscopic techniques, such as photodynamic therapy (PDT), argon plasma coagulation (APC), and endoscopic mucosal resection. In this article, we will discuss primarily photodynamic therapy, and other ablative technologies such as argon plasma coagulation in the treatment of BE.