Discordance between flow cytometric abnormalities and dysplasia in Barrett's esophagus

Ploidy and Proliferation Evaluated by Flow Cytometry. An Overview of Techniques and Impact in Oncology

Flow cytometric methods for the assessment of nuclear and chromosomal DNA content and of cell proliferation (including methods based on pulse-chase of bromodeoxyuridine and on monoclonal antibodies against nuclear oncoproteins and proliferation-associated antigens) are illustrated by examples and analyzed critically. The impact of most of these techniques for the study of human solid tumors, with exception of nuclear DNA content evaluation, appears still limited. In particular, new studies of cell lines and clinical material from human tumors using new proliferation markers and multiparameter flow cytometry are necessary to solve a considerable number of methodologic and scientific problems.

Genetic Insights in Barrett's Esophagus and Esophageal Adenocarcinoma

Beginning in the 1980s, an alarming rise in the incidence of esophageal adenocarcinoma (EA) led to screening of patients with reflux to detect Barrett's esophagus (BE) and surveillance of BE to detect early EA. This strategy, based on linear progression disease models, resulted in selective detection of BE that does not progress to EA over a lifetime (overdiagnosis) and missed BE that rapidly progresses to EA (underdiagnosis). Here we review the historical thought processes that resulted in this undesired outcome and the transformation in our understanding of genetic and evolutionary principles governing neoplastic progression that has come from application of modern genomic technologies to cancers and their precursors. This new synthesis provides improved strategies for prevention and early detection of EA by addressing the environmental and mutational processes that can determine "windows of opportunity" in time to detect rapidly progressing BE and distinguish it from slowly or nonprogressing BE.

Medical and endoscopic management of high-grade dysplasia in Barrett's esophagus

The management of high-grade dysplasia in Barrett's esophagus has clearly changed over recent years. The risk of cancer development is still substantial, with about one in three patients developing cancer, but a number of patients do not develop cancer. The nature of high-grade dysplasia has also been genetically elucidated with more evidence of chromosomal instability being present at this stage than previously thought. Therapy of the condition has evolved more toward endoscopic therapy, given the good results of radio-frequency ablation and photodynamic therapy in eliminating dysplasia and decreasing cancer development in randomized controlled trial. The best candidates for treatment include compliant patients that have relatively short segments of Barrett's esophagus, an anatomically straight segment, lack of nodularity, and an intact p16. However, even with excellent long-term results similar to surgical resection, the risk of recurrence is present in over 14% of patients, which indicates that there will be a need to continue surveillance endoscopy in these patients.

Early events during neoplastic progression in Barrett's esophagus

Barrett's esophagus is a condition in which the stratified squamous epithelium of the distal esophagus is replaced by specialized intestinal metaplasia. Clinical management of Barrett's esophagus, like many other "premalignant" conditions, is characterized by overdiagnosis of benign early changes that will not cause death or suffering during the lifetime of an individual and underdiagnosis of life-threatening early disease. Recent studies of a number of different types of cancer have revealed much greater genomic complexity than was previously suspected. This genomic complexity could create challenges for early detection and prevention if it develops in premalignant epithelia prior to cancer. Neoplastic progression unfolds in space and time, and Barrett's esophagus provides one of the best models for rapid advances, including "gold standard" cohort studies, to distinguish individuals who do and do not progress to cancer. Specialized intestinal metaplasia has many properties that appear to be protective adaptations to the abnormal environment of gastroesophageal reflux. A large body of evidence accumulated over several decades implicates chromosome instability in neoplastic progression from Barrett's esophagus to esophageal adenocarcinoma. Small, spatial scale studies have been used to infer the temporal order in which genomic abnormalities develop during neoplastic progression in Barrett's esophagus. These spatial studies have provided the basis for prospective cohort studies of biomarkers, including DNA content abnormalities (tetraploidy, aneuploidy) and a biomarker panel of 9p LOH, 17p LOH and DNA content abnormalities. Recent advances in SNP array technology provide a uniform platform to assess chromosome instability.

Aneuploidy and overexpression of Ki67 and p53 as markers for neoplastic progression in Barrett's esophagus: a case-control study

OBJECTIVES

Surveillance of patients with Barrett's esophagus (BE) aims at early detection and treatment of neoplastic changes, particularly esophageal adenocarcinoma (EAC). The histological evaluation of biopsy samples has its limitations, and biomarkers may improve early identification of BE patients at risk for progression to EAC. The aim of this study was to determine the predictive value of p53, Ki67, and aneuploidy as markers of neoplastic progression in BE.

METHODS

A total of 27 BE patients with histologically proven progression to high-grade dysplasia (HGD) or EAC (cases) and 27 BE patients without progression (controls) were selected and matched for age, gender, and duration of follow-up. Dysplasia grade was determined in 212 biopsy samples obtained during surveillance endoscopies from cases and in 231 biopsy samples collected from controls. DNA ploidy status was determined by flow cytometry, whereas Ki67 and p53 expression was determined by immunohistochemistry. Hazard ratios (HRs) were calculated by Cox regression adjusted for potentially confounding variables.

RESULTS

A univariate analysis showed that low-grade dysplasia (LGD) increased the risk of developing HGD/EAC compared with no dysplasia (HR 3.6; 95% confidence interval (CI): 1.6 - 8.1). Aneuploidy (HR 3.5; 95% CI: 1.3-9.4), strong Ki67 overexpression (HR 5.2; 95% CI: 1.5-17.6), and moderate p53 overexpression (HR 6.5; 95% CI: 2.5-17.1) were also associated with an increased risk of developing HGD/EAC, independent of the histological result. A multivariable analysis showed that in the presence of LGD, p53 overexpression, and to a lesser extent, Ki67 overexpression remained important risk factors for neoplastic progression, whereas aneuploidy was no longer predictive.

CONCLUSIONS

p53 overexpression and, to a lesser extent, Ki67 overexpression could predict neoplastic progression in BE irrespective of the histological result. These markers may be useful for identifying patients at an increased risk of developing EAC, either alone or used as a panel.

Assessment of chromosomal gains as compared to DNA content changes is more useful to detect dysplasia in Barrett's esophagus brush cytology specimens

Abnormal DNA ploidy status has been suggested as a prognostic factor for Barrett's esophagus progression into esophageal adenocarcinoma (EAC). The aim of the study was to compare image cytometry DNA analysis (ICDA) and fluorescent in situ hybridization (FISH) in the assessment of DNA ploidy status in Barrett's esophagus (BE), and to determine the value of these abnormalities as an adjunct to conventional cytology in detection of dysplasia and EAC. Brush cytology specimens of 90 BE patients were examined using ICDA and FISH with peri-centromeric probes for chromosomes 7 and 17. The results of ICDA and FISH were compared with each other, and with dysplasia grade or EAC as determined by histology and cytology. FISH and ICDA detected abnormalities in 41% (37/90) and 22% (19/90) of the BE cases, respectively. Gains of chromosome 7 and/or 17 were present in 13% of nondysplasia cases, which further increased with dysplasia stage, while overall DNA content aneuploidy was detected predominantly in high grade dysplasia (HGD) and EAC. Using FISH results combined with cytology, we were able to identify IND/LGD (indefinite/ low grade dysplasia) with a sensitivity and specificity of 75 and 76%, respectively. FISH alone detected HGD/EAC with a high sensitivity and specificity of 85 and 84%, which was superior to that of cytology alone. Thus, FISH is more sensitive than ICDA to detect chromosomal abnormalities in BE brush cytology specimens. FISH detects chromosomal gains in early stages of BE and represents a valuable adjunct to conventional cytology to detect dysplasia or EAC.

Conclusions from the histological diagnosis of low-grade intraepithelial neoplasia in Barrett's oesophagus

OBJECTIVE

It is well known that low-grade intraepithelial neoplasia (LGIN) in Barrett's oesophagus (BE) might progress to high-grade intraepithelial neoplasia (HGIN) or carcinoma. Since accurate diagnosis of LGIN is difficult, general pathologists are frequently uncertain about the diagnosis of LGIN and its follow-up risks. The purpose of this study was to analyse the divergence between the diagnoses of general and specialized gastrointestinal pathologists.

MATERIAL AND METHODS

Fifty consecutive patients with a previous diagnosis of LGIN in BE, made by a general pathologist, were included in our study. The histopathological slides of every patient were reassessed in a blinded fashion by two specialized gastrointestinal (GI) pathologists. Inter-observer variability was calculated using kappa statistics.

RESULTS

LGIN was confirmed by specialized pathologists in only 25/50 patients (50%). Twenty-one patients (42%) had Barrett's metaplasia without intraepithelial neoplasia and in 4 patients (8%) HGIN or Barrett's carcinoma (BC) was revealed. Inter-observer agreement between the general and specialized pathologists for the diagnosis of LGIN was poor (kappa = - 0.17) and good between both of the specialized pathologists (kappa = 0.69). Patients with HGIN/BC were treated by endoscopic resection or surgery. In patients with LGIN, ablative therapy was performed. Complete response was achieved in 25 patients, but 3 patients developed HGIN and 1 patient developed BC after 10+/-3.6 months.

CONCLUSIONS

BE with LGIN is difficult to diagnose. Inter-observer variability is unacceptable between general and specialized pathologists and therefore when diagnosing LGIN a second opinion should always be sought by a specialized GI pathologist. Ablation therapy seems to be effective in patients with LGIN, but follow-up endoscopies are necessary to detect metachronous neoplasia.

NSAIDs modulate CDKN2A, TP53, and DNA content risk for progression to esophageal adenocarcinoma

BACKGROUND

Somatic genetic CDKN2A, TP53, and DNA content abnormalities are common in many human cancers and their precursors, including esophageal adenocarcinoma (EA) and Barrett's esophagus (BE), conditions for which aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) have been proposed as possible chemopreventive agents; however, little is known about the ability of a biomarker panel to predict progression to cancer nor how NSAID use may modulate progression. We aimed to evaluate somatic genetic abnormalities with NSAIDs as predictors of EA in a prospective cohort study of patients with BE.

METHODS AND FINDINGS

Esophageal biopsies from 243 patients with BE were evaluated at baseline for TP53 and CDKN2A (p16) alterations, tetraploidy, and aneuploidy using sequencing; loss of heterozygosity (LOH); methylation-specific PCR; and flow cytometry. At 10 y, all abnormalities, except CDKN2A mutation and methylation, contributed to EA risk significantly by univariate analysis, ranging from 17p LOH (relative risk [RR] = 10.6; 95% confidence interval [CI] 5.2-21.3, p < 0.001) to 9p LOH (RR = 2.6; 95% CI 1.1-6.0, p = 0.03). A panel of abnormalities including 17p LOH, DNA content tetraploidy and aneuploidy, and 9p LOH was the best predictor of EA (RR = 38.7; 95% CI 10.8-138.5, p < 0.001). Patients with no baseline abnormality had a 12% 10-y cumulative EA incidence, whereas patients with 17p LOH, DNA content abnormalities, and 9p LOH had at least a 79.1% 10-y EA incidence. In patients with zero, one, two, or three baseline panel abnormalities, there was a significant trend toward EA risk reduction among NSAID users compared to nonusers (p = 0.01). The strongest protective effect was seen in participants with multiple genetic abnormalities, with NSAID nonusers having an observed 10-y EA risk of 79%, compared to 30% for NSAID users (p < 0.001).

CONCLUSIONS

A combination of 17p LOH, 9p LOH, and DNA content abnormalities provided better EA risk prediction than any single TP53, CDKN2A, or DNA content lesion alone. NSAIDs are associated with reduced EA risk, especially in patients with multiple high-risk molecular abnormalities.

Multistage carcinogenesis in Barrett's esophagus

The multistage carcinogenesis of esophageal adenocarcinoma is a process of clonal evolution within Barrett's esophagus neoplasms. The initiating event for Barrett's esophagus is unknown, but is associated with chronic gastric reflux which probably also promotes progression. Inactivation of both alleles of CDKN2A appear to be early events causing clonal expansion. Clones with TP53 inactivated expand if they have already inactivated CDKN2A. After TP53 has been inactivated, tetraploid and aneuploid clones tend to develop. The final events that lead to invasion and metastasis are unknown. Evolutionary biology provides important tools to understand clonal evolution in progression and cancer prevention.

Dysplasia and risk of further neoplastic progression in a regional Veterans Administration Barrett's cohort

OBJECTIVES

No published data are available on the risk of further neoplastic progression in Barrett's patients stratified by baseline dysplasia status. Our aims were to estimate and compare the risk of progression to high-grade dysplasia or cancer in groups of Barrett's patients stratified by baseline dysplasia status.

METHODS

Consecutive Barrett's cases from 1988-2002 were identified via pathology databases in a regional VA health-care system and medical record data were abstracted. The risk of progression to high-grade dysplasia or cancer was measured and compared in cases with versus without low-grade dysplasia within 1 yr of index endoscopy using survival analysis.

RESULTS

A total of 575 Barrett's cases had 2,775 patient-years of follow-up. There were 13 incident cases of high-grade dysplasia and two of cancer. The crude rate of high-grade dysplasia or cancer was 1 of 78 patient-years for those with baseline dysplasia versus 1 of 278 patient-years for those without (p= 0.001). One case of high-grade dysplasia in each group underwent successful therapy. One incident cancer case underwent successful resection and the other was unresectable. Two cases with high-grade dysplasia later developed cancer, one died postoperatively, the other was unresectable. When these two cases were included (total of four cancers), the crude rate of cancer was 1 of 274 patient-years for those with baseline dysplasia versus 1 of 1,114 patient-years for those without.

CONCLUSIONS

In a large cohort study of Barrett's, incident malignancy was uncommon. The rate of progression to high-grade dysplasia or cancer was significantly higher in those with baseline low-grade dysplasia. These data may warrant reevaluation of current Barrett's surveillance strategies.

Evaluation of p53 mutations in premalignant esophageal lesions and esophageal adenocarcinoma using laser capture microdissection

p53 mutations have been implicated in the development of esophageal malignancies. The purpose of this study was to assess more accurately the incidence and types of p53 mutations in Barrett's esophagus (BE) with and without dysplasia and in esophageal adenocarcinoma, using pure preparations of epithelial cells obtained by laser capture microdissection (LCM). Assays were performed on paraffin-embedded tissue samples of normal antrum and premalignant and malignant esophageal samples from 57 patients, including 16 controls, 10 with BE metaplasia alone, 20 with BE-associated dysplasia, and 11 with BE-associated adenocarcinoma. All tissues were processed for LCM. DNA was extracted from isolated cells, and polymerase chain reaction (PCR) was performed using oligonucleutide primers for exons 5-8 of p53. PCR products were processed for DNA sequencing. p53 sequence abnormalities were identified in 2/16 cases of normal antrum and regenerative/chemical gastritis, 1/10 cases of BE, 1/20 cases of BE with dysplasia, and 2/11 cases of adenocarcinomas. The abnormalities occurred in exons 7 and 8 in the form of point mutations. Our results, using LCM, show that p53 gene mutations are relatively rare in esophageal preneoplastic and neoplastic conditions. Only point mutations were detected, but no deletions/insertions were identified.

DNA abnormalities as marker of risk for progression of Barrett's esophagus to adenocarcinoma: image cytometric DNA analysis in formalin-fixed tissues

OBJECTIVES

To examine DNA content abnormalities in patients with Barrett's esophagus (BE) who progress to esophageal adenocarcinoma, using image cytometric DNA analysis (ICDA) of formalin-fixed tissues.

METHODS

Studies were performed on archived biopsies of BE patients' undergoing endoscopic surveillance before developing adenocarcinoma. A comparison group consisted of BE patients' free of cancer during a follow-up period of over 9 yr. Tissue sections were analyzed for the degree of dysplasia and for DNA content abnormalities, using image cytometry. Additional patients were also analyzed in a cross-sectional study of 56 BE cases with and without dysplasia, including 12 cases of adenocarcinoma.

RESULTS

Five patients developed adenocarcinoma during follow-up and earlier biopsies obtained before cancer diagnosis showed specialized intestinal metaplasia (SIM) followed by low-grade dysplasia (LGD) in one, SIM followed by high-grade dysplasia (HGD) in one, LGD in two, and HGD in one case. All five showed some DNA abnormality at baseline or in interval biopsies. In the comparison group, five of seven patients showed normal diploid DNA at baseline and on follow-up biopsies. One patient initially had diploid DNA, but developed aneuploidy 11 yr later. Another case initially had aneuploidy, but was diploid on follow-up. Overall, DNA abnormalities were found in 13% of cases with SIM without dysplasia, 60% with LGD, 73% with HGD, and 100% with adenocarcinoma.

CONCLUSIONS

(i) Image cytometric DNA analysis is a useful method to examine DNA abnormalities in formalin-fixed tissues and may be more sensitive in predicting progression to adenocarcinoma than HGD. (ii) Histological dysplasia of any grade and DNA abnormalities, help identify BE patients at high risk for adenocarcinoma.

Barrett's esophagus: model of neoplastic progression

Human cancer progression is characterized by clonal expansion of cells with accumulated genetic errors. Invasive carcinomas contain all the genetic errors that were acquired during neoplastic progression and then continue to accumulate further abnormalities, leading to tumor heterogeneity. Many investigations of human cancer have given valuable insights in genetic abnormalities important for tumor biology. Early events responsible for neoplastic progression, however, are often impossible to investigate in invasive cancers because the premalignant tissue in which the tumors develop are often overgrown and the premalignant conditions cannot be studied in vivo because they are either not detected owing to lack of symptoms or are removed before cancer develops. Unlike many other premalignant conditions Barrett's esophagus is often associated with symptoms leading to diagnosis at an early stage before cancer develops, and the premalignant epithelium is seldom removed at an early stage of cancer progression. Furthermore, in patients who present with invasive carcinoma the tumor is often surrounded by premalignant epithelium, which is available for further investigations. Therefore Barrett's esophagus is an excellent model in which to study the early events of neoplastic progression. It may not only contribute to a better understanding of the neoplastic process but also provide a base for safer assessment of cancer risk during surveillance for early detection of esophageal adenocarcinoma.

Biomarkers in Barrett's esophagus

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

Barrett's esophagus and Barrett's-related dysplasia

Barrett's esophagus is a complication of chronic gastroesophageal reflux disease and can be diagnosed when there is an endoscopic abnormality in which a biopsy shows evidence of specialized columnar epithelium, characterized by the presence of acid mucin-containing goblet cells. Much of the controversy in this body of literature relates to the complex anatomy of the esophagogastric junction and the difficulty in precisely identifying this landmark at endoscopy. By definition, in Barrett's esophagus, the squamocolumnar junction is proximal to the esophagogastric junction. Although fundic-type or cardiac-type (junctional) columnar epithelium may be present in Barrett's esophagus, it is only the presence of specialized columnar epithelium that is diagnostic of this condition. Patients with Barrett's esophagus are at risk of progressing to esophageal dysplasia and adenocarcinoma. There are several problems with using dysplasia as a marker for increased cancer risk in these patients, including problems with sampling error and intra- and interobserver variation in the recognition of dysplasia. It may be difficult to distinguish regenerative epithelial changes from dysplasia, low-grade from high-grade dysplasia, and high-grade dysplasia from intramucosal adenocarcinoma. Finally, there are relatively few prospective data evaluating the natural history of high-grade dysplasia. The management of patients with Barrett's-related dysplasia is controversial and varies from institution to institution. Future emphasis should be on cost-effective techniques for sampling as much of the esophageal mucosa as possible in patients who are at the highest risk of progressing to dysplasia and adenocarcinoma. Identification of biomarkers that identify such patients before the histologic recognition of dysplasia will be an area of intensive research.

Barrett's esophagus: clinical characteristics

Barrett's metaplasia develops in 6-14% of individuals with gastroesophageal reflux. Barrett's adenocarcinomas are increasing in epidemic proportions for as yet unknown reasons, approximately 0.5-1% of patients with Barrett's will develop adenocarcinoma. Heartburn duration and frequency (but not severity), male gender, and Caucasian race are major risk factors for developing cancer. Obesity and smoking are weak risk factors. Survival is determined by depth of tumor invasion (stage). Once invasion of the muscularis propia occurs, the vast majority of patients will have developed widespread metastasis, even when clinical staging studies are negative. No currently available therapy results in prolonged survival once metastases develop. Thus, the more widespread use of effective surveillance strategies is the only currently available means for reducing the morbidity and mortality associated with Barrett's adenocarcinoma.

Dysplasia in barrett's esophagus. New techniques and markers

In this article, the authors describe the histologic features and classification of dysplasia in Barrett's esophagus. The histologic problems in the diagnosis and grading of dysplasia are discussed. Techniques that can serve as aids to the histologic diagnosis of dysplasia, such as flow cytometry and molecular markers, are reviewed.

Endosonography in the evaluation of patients with Barrett's esophagus and high-grade dysplasia

Endosonography, which provides high-resolution images of the esophageal wall, could potentially detect carcinoma not visible endoscopically in patients with Barrett's esophagus and high-grade dysplasia. We studied the ability of endosonography to detect early esophageal carcinoma in 9 patients with Barrett's esophagus and high-grade dysplasia who were candidates for esophagectomy. Pre-operative endoscopy and biopsy revealed high-grade dysplasia without evidence of carcinoma in all patients. Pre-operative endosonographic evaluations were compared to the pathologic diagnoses of resected specimens. Post-operatively, 3 of the 9 patients were found to have intra-mucosal carcinoma. Endosonography identified a tumor in only 1 of these 3 patients and over-staged it as invasive carcinoma (T2, N1). In 2 of the 6 patients without intra-mucosal carcinoma, endosonography predicted invasive carcinoma (T2, N0). Endoscopy revealed mucosal nodularity in each of the 3 over-staged patients. We conclude that recommendation of the routine use of endosonography to determine the need for surgery in patients with Barrett's esophagus and high-grade dysplasia would be premature, because the current generation of echo-endoscopes does not reliably differentiate between benign and malignant wall thickening.

Molecular biology of Barrett's adenocarcinoma

OBJECTIVE

To review the current knowledge on the genetic alterations involved in the development and progression of Barrett's esophagus-associated neoplastic lesions.

SUMMARY BACKGROUND DATA

Barrett's esophagus (BE) is a premalignant condition in which the normal squamous epithelium of the esophagus is replaced by metaplastic columnar epithelium. BE predisposes patients to the development of esophageal adenocarcinoma. Endoscopic surveillance can detect esophageal adenocarcinomas when they are early and curable, but most of the adenocarcinomas are detected at an advanced stage. Despite advances in multimodal therapy, the prognosis for invasive esophageal adenocarcinoma is poor. A better understanding of the molecular evolution of the Barrett's metaplasia to dysplasia to adenocarcinoma sequence may allow improved diagnosis, therapy, and prognosis.

METHODS

The authors reviewed data from the published literature to address what is known about the molecular changes thought to be important in the pathogenesis of BE-associated neoplastic lesions.

RESULTS

The progression of Barrett's metaplasia to adenocarcinoma is associated with several changes in gene structure, gene expression, and protein structure. Some of the molecular alterations already showed promise as markers for early cancer detection or prognostication. Among these, alterations in the p53 and p16 genes and cell cycle abnormalities or aneuploidy appear to be the most important and well-characterized molecular changes. However, the exact sequence of events is not known, and probably multiple molecular pathways interact and are involved in the progression of BE to adenocarcinoma.

CONCLUSIONS

Further research into the molecular biology of BE-associated adenocarcinoma will enhance our understanding of the genetic events critical for the initiation and progression of Barrett's adenocarcinoma, leading to more effective surveillance and treatment.

Endoscopic detection of dysplasia in patients with Barrett's esophagus using light-scattering spectroscopy

BACKGROUND & AIMS

We conducted a study to assess the potential of light-scattering spectroscopy (LSS), which can measure epithelial nuclear enlargement and crowding, for in situ detection of dysplasia in patients with Barrett's esophagus.

METHODS

Consecutive patients with suspected Barrett's esophagus underwent endoscopy and systematic biopsy. Before biopsy, each site was sampled by LSS using a fiberoptic probe. Diffusely reflected white light was spectrally analyzed to obtain the size distribution of cell nuclei in the mucosal layer, from which the percentage of enlarged nuclei and the degree of crowding were determined. Dysplasia was assigned if more than 30% of the nuclei exceeded 10 microm and the histologic findings compared with those of 4 pathologists blinded to the light-scattering assessment. The data were then retrospectively analyzed to further explore the diagnostic potential of LSS.

RESULTS

Seventy-six sites from 13 patients were sampled. All abnormal sites and a random sample of nondysplastic sites were reviewed by the pathologists. The average diagnoses were 4 sites from 4 different patients as high-grade dysplasia (HGD), 8 sites from 5 different patients as low-grade dysplasia (LGD), 12 as indefinite for dysplasia, and 52 as nondysplastic Barrett's. The sensitivity and specificity of LSS for detecting dysplasia (either LGD or HGD) were 90% and 90%, respectively, with all HGD and 87% of LGD sites correctly classified. Decision algorithms using both nuclear enlargement and crowding further improved diagnostic accuracy, and accurately classified samples into the 4 histologic categories.

CONCLUSIONS

LSS can reliably detect LGD and HGD in patients with Barrett's esophagus.

The diagnosis of dysplasia and malignancy in Barrett's oesophagus

Barrett's metaplasia is associated with an increased risk for adenocarcinoma. Adenocarcinoma develops through a multistep process characterized by defects in genes and morphological abnormalities. The early morphological changes of the process are called 'dysplasia'. Dysplasia is defined as an unequivocal neoplastic (premalignant) transformation confined within the basement membrane. For most Western pathologists malignancy is defined as invasion and characterized by a breach through the basement membrane. Japanese pathologists rely on cytological atypia and complex branching of crypts. Cytological and architectural abnormalities allow identification of dysplasia on routinely stained sections. A distinction is made between low- and high-grade dysplasia. The differential diagnosis between low-grade dysplasia and reactive changes can be difficult. Therefore a second opinion is strongly recommended, not only for high-grade dysplasia but also for low-grade. Immunohistochemistry for p53 and flow cytometry for detection of aneuploidy can support the diagnosis. Identification of dysplasia and malignancy depends on the number of biopsy samples examined. The minimum number of biopsies required has not yet been determined and depends partly on the length of the metaplastic segment. It has been proposed to sample with four quadrant biopsies at 20-mm intervals. New endoscopic techniques can increase the diagnostic yield. Endoscopically visible lesions increase the risk of finding malignancy. The time sequence for the progression of dysplasia is not known but progression from low- to high-grade and cancer has been shown to occur over a period of years although it may not be inevitable.

Predictors of progression to cancer in Barrett's esophagus: baseline histology and flow cytometry identify low- and high-risk patient subsets

OBJECTIVE

Barrett's esophagus develops in 5-20% of patients with gastroesophageal reflux disease and predisposes to esophageal adenocarcinoma. The value of endoscopic biopsy surveillance is questioned because most patients do not develop cancer. Furthermore, observer variation in histological diagnosis makes validation of surveillance guidelines difficult because varying histological interpretations may lead to different estimated rates of progression. Thus, objective biomarkers need to be validated for use with histology to stratify patients according to their risk for progression to cancer.

METHODS

We prospectively evaluated patients using a systematic endoscopic biopsy protocol with baseline histological and flow cytometric abnormalities as predictors and cancer as the outcome.

RESULTS

Among patients with negative, indefinite, or low-grade dysplasia, those with neither aneuploidy nor increased 4N fractions had a 0% 5-yr cumulative cancer incidence compared with 28% for those with either aneuploidy or increased 4N. Patients with baseline increased 4N, aneuploidy, and high-grade dysplasia had 5-yr cancer incidences of 56%, 43%, and 59%, respectively. Aneuploidy, increased 4N, or HGD were detected at baseline in all 35 patients who developed cancer within 5 yr.

CONCLUSIONS

A systematic baseline endoscopic biopsy protocol using histology and flow cytometry identifies subsets of patients with Barrett's esophagus at low and high risk for progression to cancer. Patients whose baseline biopsies are negative, indefinite, or low-grade displasia without increased 4N or aneuploidy may have surveillance deferred for up to 5 yr. Patients with cytometric abnormalities merit more frequent surveillance, and management of high-grade dysplasia can be individualized.

Relationship between dysplasia, p53 protein accumulation, DNA ploidy, and Glut1 overexpression in Barrett metaplasia

BACKGROUND

There is a need for molecular markers of malignant progression in Barrett metaplasia (BM). The aim of this study is to determine the relationship between dysplasia, p53 protein accumulation, DNA ploidy, and Glut1 in BM.

METHODS

Sections of esophageal biopsy specimens from 120 patients with BM were evaluated for dysplasia, p53 protein, and Glut1 expression by immunohistochemistry, and DNA ploidy by Feulgen stain and image analysis. In cases with diploid DNA histograms, the percentage cells in the G0G1 and G2M phases of the cell cycle were determined.

RESULTS

Of 108 diploid cases 19 (28%) of 69 cases with G0G1 > or = 90% or G2M > or = 8.33% were p53-positive, in contrast to only 1 (3%) of 39 cases with lower G0G1 or G2M (P = 0.0008). Of 32 p53-positive cases 11 (32%) were aneuploid, in contrast to none (0%) of 88 p53-negative cases (P < 0.0001). Ten (91%) of 11 aneuploid cases were high-grade dysplasial adenocarcinoma (HGD/CA), compared with only 1 (1%) of 109 diploid cases (P < 0.0001). Five (45%) of 11 cases with HGD/CA were Glut1-positive, in contrast to none (0%) of 109 cases without HGD/CA (P < 0.0001).

CONCLUSIONS

Our data strongly suggest that in BM, after oxidative DNA damage, as a result of gastroesophageal reflux, there is an increase in the percentage of cells in the G0G1 or G2M phases of the cell cycle to enable repair of damaged DNA; in some of these cases this is followed sequentially by p53 gene mutation and protein accumulation, DNA aneuploidy, HGD, and CA with or without Glut1 overexpression. These events can be detected in routinely processed biopsy samples.

Clonal expansion and loss of heterozygosity at chromosomes 9p and 17p in premalignant esophageal (Barrett's) tissue

BACKGROUND

Abnormalities involving the p16 (also known as cyclin-dependent kinase N2 [CDKN2], p16 [INK4a], or MTS1) and p53 (also known as TP53) tumor suppressor genes are highly prevalent in esophageal adenocarcinomas. Loss of heterozygosity (LOH) at 9p21 and 17p13 chromosomes (locations for p16 and p53 genes, respectively) is frequently observed in the premalignant condition, Barrett's esophagus. We studied extensively the distribution and heterogeneity of LOH at 9p and 17p chromosomes throughout the Barrett's segment in patients who have not yet developed esophageal adenocarcinoma.

METHODS

We evaluated 404 samples from 61 consecutive patients enrolled in the Seattle Barrett's Esophagus Study from February 1995 through September 1998. All patients had high-grade dysplasia but no diagnosis of cancer. The samples were assayed for LOH at 9p and 17p chromosomes after amplification of genomic DNA by use of polymerase chain reaction and DNA genotyping. The cell fractions were purified by flow cytometry on the basis of DNA content and proliferation-associated antigen labeling. Association between LOH at 9p and LOH at 17p with flow cytometric abnormalities was determined by chi-squared test, and logistic regression models were used to model and test for the extent to which a particular genotype was found in 2-cm intervals.

RESULTS AND CONCLUSIONS

LOH at 9p and 17p chromosomes are highly prevalent somatic genetic lesions in premalignant Barrett's tissue. LOH at 9p is more common than LOH at 17p in diploid samples and can be detected over greater regions of Barrett's epithelium. In most patients with high-grade dysplasia, the Barrett's mucosa contains a mosaic of clones and subclones with different patterns of LOH. Some clones had expanded to involve extensive regions of Barrett's epithelium. LOH at 9p and 17p chromosomes may be useful biomarkers to stratify patients' risk of progression to esophageal cancer.

Barrett's esophagus. Reducing the risk of progression to adenocarcinoma

Barrett's metaplasia develops in 6% to 14% of individuals with gastroesophageal reflux. Barrett's adenocarcinomas are increasing in epidemic proportions for, as yet unknown, reasons; approximately 0.5% to 1% of patients with Barrett's metaplasia develop adenocarcinoma. Heartburn duration and frequency (but not severity), male gender, and white race are major risk factors for developing cancer. Obesity and smoking are weak risk factors. Survival is determined by depth of tumor invasion (stage). Once invasion of the muscularis propria occurs, most patients have developed widespread metastasis, even when clinical staging studies are negative. No currently available therapy results in prolonged survival once metastases develop. Thus, the more widespread use of effective surveillance strategies is the only currently available means for reducing the morbidity and mortality associated with Barrett's adenocarcinoma.

Esofagectomia transiatal para o tratamento do adenocarcinoma do esôfago

A esofagite de refluxo associada ao epitélio de colunar do esôfago predispõe ao adenocarcinoma, cuja incidência vem aumentando nos últimos anos. Entre 1976 e 1993, os autores trataram 11 pacientes com adenocarcinoma primário do esôfago. Em dois casos, a neoplasia desenvolveu-se em epitélio colunar ectópico no esôfago cervical e torácico. Nos demais casos, ocorreu no terço distal do esôfago em epitélio colunar de Barrett, em pacientes com sintomas clínicos de esofagite de refluxo, dos quais sete eram portadores de hérnia de hiato e refluxo gastroesofágico previamente documentados. Nove pacientes foram submetidos a esofagectomia transiatal com esofagogastroplastia, um foi submetido a esofagectomia distal com interposição de jejuno e o último a esofagogastroplastia retroestemal sem esofagectomia. A exceção de três pacientes, os demais tiveram operações consideradas curativas. Cinco doentes encontravam-se em estádios mais iniciais, ainda sem comprometimento linfonodal. Não houve mortalidade operatória, sendo que as principais complicações foram a fístula da anastomose esofagogástrica e a abertura da cavidade pleural, ambas ocorrendo em dois pacientes. A sobrevida média dos pacientes foi de 40,5 meses. Três pacientes permanecem vivos e sem evidência de doença (estádio 0, I e IIA) com 64, 94 e 117 meses de seguimento. Concluiu-se que a esofagectomia neste tipo de tumor é um procedimento seguro e que a sobrevida a longo prazo é possível quando os tumores em estadio inicial são tratados adequadamente.

Barrett's Esophagus and Barrett's Associated Neoplasia: Etiology and Pathologic Features

BACKGROUND: The incidence of Barrett's esophagus (BE) has been increasing in recent years. Patients with BE have 30- to 125-fold increased risk of developing adenocarcinoma. New techniques allowing early diagnosis, in addition to the identification of markers capable of predicting tumor progression, are needed. METHODS: The authors discuss the diagnostic features of BE and BE-associated neoplasia. RESULTS: BE can exhibit different types of metaplastic mucosa, but only the specialized (intestinal) mucosa has the potential to progress to dysplasia and carcinoma. The problems associated with diagnosing BE and with predicting the behavior of this condition are outlined. CONCLUSIONS: Studies are underway to identify molecular markers capable of predicting which BE patient will progress to carcinoma. Brush cytology and flow cytometry may become useful tools in the early detection of this disease.

Flow cytometric DNA analysis and p53 protein expression show a good correlation with histologic findings in patients with Barrett's esophagus

BACKGROUND

There is a considerable degree of subjectivity and, therefore, substantial interobserver and intraobserver disagreement in the diagnosis and grading of dysplastic lesions in Barrett's esophagus (BE). The aim of this study was to evaluate the usefulness of DNA flow cytometry and immunohistochemical staining for p53 protein as objective methods to complement the conventional histologic diagnosis of dysplasia in patients with this disease. The most common problems and the possible advantages of using these procedures are analyzed briefly in this article.

METHODS

Formalin fixed, paraffin embedded tissue from 55 patients diagnosed with BE were processed for flow cytometric measurements (ploidy and proliferation index) and p53 immunostaining.

RESULTS

Both the cytometric data and the positivity of staining for p53 revealed a statistically significant increase throughout the following sequence: no dysplasia --> indefinite for dysplasia --> low grade dysplasia --> high grade dysplasia --> adenocarcinoma. There was also a highly significant correlation between the results of the cytometric study and the positivity of staining for p53.

CONCLUSIONS

In the future, the use of this procedure could play an important role in the evaluation of patients with BE. Considering that staining for p53 is technically simple, economical, and quick, and the materials required are available to most pathology laboratories, this method appears to be a firm candidate for application as a biomarker in BE. The authors have shown that it is possible to obtain adequate results for cytometric analysis with small formalin fixed, paraffin embedded biopsies if a strict protocol for the acceptance of tissue samples and/or histograms is observed.

The histopathology and biologic prognostic factors of Barrett's esophagus: a review

In Barrett's esophagus, stratified squamous mucosa of the lower third of the esophagus is replaced by columnar mucosa, as a complication of chronic gastroesophageal reflux. The presence of Barrett's esophagus appears to be a major factor in the progression to adenocarcinoma of the lower third of the esophagus. Therefore it is crucial to identify the subset of patients at risk for the development of adenocarcinoma. Dysplasia is an important histologic feature to evaluate because it identifies those patients who require follow-up. The diagnosis of biopsies with lesser degrees of abnormalities, however, makes microscopic evaluation less helpful in identifying patients who need more frequent endoscopic biopsy surveillance. DNA ploidy and the use of monoclonal antibodies, such as suppressor gene product p53, oncogene cerbB-2, and Ki-67, have added dramatically to our understanding of the biology of Barrett's metaplasia and have given us objective indicators to predict the presence of an increased risk of developing cancer.

Morphology of Barrett's esophagus and Barrett's-associated dysplasia and adenocarcinoma

This article has reviewed the morphologic features of BE and its complications of dysplasia and adenocarcinoma in routinely processed endoscopic biopsy and resection specimens. In addition, the problems related to the diagnosis of dysplasia in tissue samples have been analyzed, and the role of esophageal brush cytology in the diagnosis of these lesions has been reviewed.

Mutations of p53 in Barrett's esophagus and Barrett's cancer: a prospective study of ninety-eight cases

We had previously identified p53 mutations in Barrett's esophagus and therefore began a multiinstitutional study to determine their significance as a marker for malignancy. Ninety-eight patients from four institutions were studied. Forty-eight patients (37 men and 11 women, mean age 56.2 years) had Barrett's esophagus with metaplasia or dysplasia but no evidence of malignancy at a mean follow-up of 2.2 years. Barrett's esophagus was classified as metaplasia with no evidence of dysplasia in 32 patients, as low-grade dysplasia in 13, and as high-grade dysplasia in three. The other 50 patients (46 men and four women, mean age 60.2 years) had adenocarcinoma arising in Barrett's esophagus. Tissues from normal stomach or esophagus, tumor, and Barrett's esophagus were obtained for deoxyribonucleic acid analysis by endoscopic biopsy from patients with Barrett's esophagus or cancer or during operations on some patients with Barrett's cancer. Exons 5 through 9 of the p53 gene were studied for mutations by single-strand conformational polymorphism analysis after polymerase chain reaction amplification. Mutations detected by single-strand conformational polymorphism analysis were confirmed by deoxyribonucleic acid sequencing. None of the tissue samples from patients with Barrett's esophagus alone and no dysplasia or low-grade dysplasia had any p53 mutations, but one of the three patients with high-grade dysplasia and no evidence of invasive malignancy did have a p53 mutation. Of the 50 patients with Barrett's cancer, however, 23 (46%) had p53 mutations in Barrett's epithelium, tumors, or both. Twenty of these patients had p53 mutations in the tumor only (n = 16) or in both tumor and Barrett's epithelium (n = 4), suggesting that the mutation plays a direct role in carcinogenesis. Mutations in Barrett's epithelium were found in one patient in the group without malignancy and in seven patients with cancer (one with no dysplasia, two with low-grade dysplasia, and five with high-grade dysplasia). In three patients with cancer, mutations occurred only in Barrett's epithelium, suggesting that such mutations may also be a marker for genomic instability. Mutations were predominantly found in exons 5, 7, and 8, and transitions from guanine to adenine were the most frequent changes. Mutations of p53 are clearly involved in the pathogenesis of Barrett's cancer for a subset of patients (46%), and the fact that we could detect mutations in premalignant Barrett's epithelium supports the hypothesis that p53 mutations may be a useful marker for patients at increased risk for development of invasive cancer.

Prognostic value of DNA index, S-phase fraction and p53 protein accumulation after surgical resection of esophageal squamous-cell carcinomas in Thailand

The prognostic value of cell nuclear DNA content, S-phase fraction and p53 protein accumulation in esophageal squamous-cell carcinomas was studied in a consecutive series of 80 patients from a high-incidence region of southern Thailand, who underwent esophagectomy between 1983 and 1993. Flow cytometry was used to determine tumor ploidy, DNA index and S-phase fraction, while p53 protein accumulation was evaluated immunohistochemically using the monoclonal anti-p53 antibody, CO7. Biomarkers were correlated with clinico-pathologic findings and survival by univariate and multivariate analysis. p53 protein was found in 40 tumors (50%), and was associated with significantly reduced overall survival. In patients with immunopositive tumors, depth of primary tumor invasion, lymph-node status. TNM stage and tumor grade were also significant prognostic factors. Additional predictors of reduced overall survival after esophagectomy, determined by flow cytometry, included S-phase fraction above 10%, aneuploidy (DNA index 1.2-1.8) and multiploidy (DNA index > 2.2). This study further implicates p53 in the pathogenesis of esophageal squamous-cell carcinoma. Prognostic factors such as p53 protein, S-phase fraction and DNA index may be useful in stratifying patients for adjuvant therapies in future clinical trials of esophageal cancer.

Flow cytometric analysis of the DNA content in colorectal adenomas with focal cancers

BACKGROUND & AIMS

Variable results have been reported on the nuclear DNA content of colorectal polyps. The significance of DNA aneuploidy in the malignant transformation of colorectal polyps was evaluated.

METHODS

We analyzed by flow cytometry the nuclear DNA content of freshly frozen samples of 50 colorectal adenomas with or without focal cancers, analyzing separately the adenomatous and cancerous regions of the polyps.

RESULTS

In the adenomatous regions of the 50 polyps, the DNA was diploid in 43 and aneuploid in 7; the adenomas with DNA aneuploidy in the adenomatous regions were more frequently accompanied by focal cancers than were the DNA-diploid adenomas (P < 0.01). In 60% of the polyps with DNA aneuploidy in the cancerous regions, the DNA was also aneuploid in the adenomatous region and had similar DNA indices; this result suggests that the DNA aneuploidy had already occurred during the adenomatous stage, which lends support to the concept of the adenoma-carcinoma sequence. DNA aneuploidy in the adenomatous region was significantly correlated with the size of colorectal polyps (P < 0.05).

CONCLUSIONS

DNA aneuploidy may be an important indicator for the early diagnosis of malignant transformation of colorectal polyps.

Barrett's esophagus, dysplasia, and adenocarcinoma

In Barrett's esophagus the normal stratified squamous epithelium lining the esophagus becomes replaced by metaplastic columnar epithelium containing goblet cells; it develops as a complication of chronic gastroesophageal reflux disease and predisposes the patient to adenocarcinoma. The frequency with which it leads to adenocarcinoma is not established with certainty, but the reported prevalence averages approximately 10% when the diagnosis of Barrett's esophagus is first made. The estimated incidence of adenocarcinoma varies from one in 152 to one in 441 cases per patient year, or a 30- to 125-fold excess risk. Esophageal adenocarcinoma arises only in patients with metaplastic columnar epithelium. Dysplasia precedes adenocarcinoma in Barrett's esophagus and arises from the metaplastic epithelium; it has been proposed as a marker for detecting patients at high risk for developing carcinoma. Problems with the use of dysplasia as a marker for cancer risk include difficulty in differentiating it from reactive change, variability in diagnosis and grading between observers and when the same observer interprets the sections on different occasions, and lack of understanding of its natural history. Methods other than dysplasia for detecting patients at highest risk for developing carcinoma have been sought, but flow cytometric analysis of DNA content is the only one proven to be valuable to date. Flow cytometric abnormalities correlate well with histological progression in Barrett's esophagus. The prevalence of elevated S phase and G2/tetraploid fractions and of aneuploid cell populations increases with histological progression from metaplasia to indefinite/low grade dysplasia to high grade dysplasia and cancer. Flow cytometric abnormalities in endoscopic biopsy specimens identify those patients with a higher risk of progression to high grade dysplasia or adenocarcinoma.

The management of high grade dysplasia and early cancer in Barrett's esophagus. A multidisciplinary problem

BACKGROUND

The incidence of Barrett's-associated esophageal adenocarcinoma is rising, but experience in the treatment of high-grade dysplasia (HGD) or early cancer is limited. Based on an endoscopic surveillance program, the authors developed a systematic multidisciplinary approach to this problem.

METHODS

Surgical resection was considered if biopsies of the Barrett's segment, performed according to a published protocol, showed invasive cancer, intramucosal carcinoma, or repeated evidence of HGD. The type of resection was based on the length of the Barrett's segment and included an en bloc lymph node dissection for staging purposes. Careful intraoperative pathologic evaluation ensured that all of the Barrett's mucosa was resected.

RESULTS

From 1984 to 1993, 27 consecutive patients (23 men, 4 women), with median age of 61 years (range, 45-75 years) underwent surgical exploration. Indications for operation were invasive cancer in 17 patients, intramucosal carcinoma in 5 patients, and HGD in 5 patients. Median length of the Barrett's segment was 9 cm (range, 1-17 cm). Only 15 patients (55%) had abnormalities visible with endoscopic examination that were potentially suspicious for malignancy. Twenty-six patients underwent resection with complete removal of the Barrett's mucosa, 20 by Ivor Lewis esophagogastrectomy, and 6 by transhiatal esophagectomy. Pathologic tumor stages were: TisN0M0 in 10 patients; T1N0M0 in 11 patients; T2N0M0 in 2 patients; T3N0M0 in 3 patients; and T1NXM1 in 1 patient. There were no postoperative deaths or anastomotic leaks. Major complications occurred in 4 patients. With a median follow-up of 3.7 years, 22 patients were alive, and only 2 patients had recurrences.

CONCLUSIONS

This increasingly important group of patients with HGD or early carcinoma in the Barrett's esophagus has a high chance of cure but requires careful multidisciplinary treatment by the surgeon, gastroenterologist, and pathologist.

p53 mutations in Barrett's adenocarcinoma and high-grade dysplasia

BACKGROUND/AIMS

Allelic losses of chromosome 17p and overexpression of p53 protein have been reported in Barrett's adenocarcinomas. This study aimed to determine the stage in which p53 mutations arise in neoplastic progression in Barrett's esophagus and their relationship to the clonal evolution of cancer.

METHODS

Fourteen patients with high-grade dysplasia, adenocarcinoma, or both arising in Barrett's esophagus were evaluated. Flow cytometric cell sorting was used to obtain purified populations of neoplastic cells for analysis of p53 mutations. DNA was extracted, and exons 5 through 9 of the p53 gene were amplified by polymerase chain reaction. Amplified DNA was sequenced and analyzed by automated sequencing.

RESULTS

Nine of the 14 patients had p53 mutations. Six of the 9 patients had regions of high-grade dysplasia that could be evaluated; all 6 had p53 mutations in high-grade dysplasia. In 3 patients, the same p53 mutations were found in both high-grade dysplasia and adenocarcinoma. All 14 patients had aneuploidy. In 4 patients, diploid cell populations could also be evaluated for p53 mutations; 3 of the 4 patients had p53 mutations in diploid cell populations. In 2 patients, the same p53 mutation was found in multiple aneuploid cell populations within a cancer.

CONCLUSIONS

p53 mutations occur frequently in Barrett's adenocarcinomas. They develop in diploid cell populations. The same p53 mutations are then found in aneuploid cell populations in high-grade dysplasia, in cancer, and in multiple aneuploid cell populations in cancer.

DNA or cell kinetics flow cytometry analysis of 33 small gastrointestinal cancers treated by photodynamic therapy

BACKGROUND

Photodynamic therapy (PDT) mediated by hematoporphyrin derivative (HPD) is a new treatment for cancers of small volume undergoing Phase II or III clinical trials in various medical fields. However, there is a lack of prognostic criteria of efficacy as in other cancer treatment.

METHODS

Cell DNA content or cell kinetics throughout the cell cycle were analyzed by flow cytometry and propidium iodide staining before and after HPD-PDT in 33 patients with Tis or T1 cancers of the gastrointestinal tract. The authors compared results in near-diploid cancers with those obtained in normal corresponding tissue.

RESULTS

Complete local tumor destruction and negative histologic findings (complete response [CR]) were observed in 17 of 33 patients during a period averaging 15.7 months. Flow cytometry DNA analysis was feasible in 32 patients. Aneuploidy, found in 15 of the 32 indicated a poor prognosis because 5 of 15 patients with aneuploid tumors were classified as having CR, compared with 12 of 17 patients with near-diploid tumors (P < 0.05). Changes in ploidy after PDT in 11 patients consisted of a reduction in the number of aneuploid peaks in 8 patients and the appearance of one aneuploid peak in 3 patients. Percentages of cells in SG2M phase in near-diploid tumors differed from those observed in control subjects for adenocarcinomas, and there was no significant decrease after HPD-PDT. There was no correlation between the decrease of SG2M cells and the response to HPD-PDT.

CONCLUSION

Results obtained with PDT in this series of patients confirm previously published findings. Changes occurring in the ploidy of PDT-treated patients demonstrate that PDT acts directly on cancer cells in humans and not only on tumor vasculature. However, response to PDT varies from one cell population to another. The appearance of aneuploid populations after PDT suggests that destruction of sensitive cell populations allows the growth of aneuploid clones that initially are not detectable by flow cytometry.

Potential application of p53 as an intermediate biomarker in Barrett's esophagus

Diagnosis of the neoplastic progression in Barrett's esophagus using the histologic classification of dysplasia is frequently difficult. The tumor suppressor protein p53, when mutated, confers a promoter effect on cell growth. The purpose of this study was to evaluate the applicability of p53 as an intermediate biomarker of malignancy in Barrett's esophagus. Archival analysis of 100 biopsy specimens of Barrett's esophagus and 10 esophageal adenocarcinomas were compared with 35 chronic esophagitis biopsy specimens. Immunocytochemistry using an anti-p53 monoclonal antibody was performed and elevated immunoreactivity quantitated microscopically. Data were analyzed using a logistic regression model. Significant p53 immunoreactivity occurred as follows: chronic esophagitis (0%), Barrett's esophagus without dysplasia (10%), with low-grade dysplasia (60%), with high-grade dysplasia (100%), and adenocarcinoma (70%). All cases of Barrett's esophagus were significantly immunoreactive when compared with the chronic esophagitis cases (p = 0.001). There was an increase in p53 immunoreactivity as the histologic classification progressed toward adenocarcinoma (p = 0.001). Progression to high-grade dysplasia may be predicted based on p53 immunoreactivity. These findings suggest a role for p53 as an intermediate biomarker in Barrett's esophagus.