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

PurposeBarrett'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 &; MethodsIn 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.ResultsWe 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.ConclusionsThese 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.     

糜烂性食管炎、Barrett食管及食管腺癌中SOX2、CDX2的表达及其临床意义

目的探讨CDX2、SOX2在糜烂性食管炎、Barrett食管的3种不同组织类型(胃底型、贲门型、肠化生型)及食管腺癌(esophageal adenocarcinoma,EAC)中的表达及意义。方法采用免疫组化Eli Vision两步法检测CDX2和SOX2在35例贲门组、23例胃底组、14例肠化组、10例糜烂性食管炎组、7例EAC组、10例正常食管下段黏膜中的表达情况。结果 CDX2在肠化组及EAC组中的阳性率均为85.7%,显著高于其他四组(P0.05);CDX2阳性率在贲门组(11.4%)、胃底组(0)、糜烂性食管炎组(0)及正常食管组(0)中的差异无显著性(P0.05)。CDX2在贲门组(75%)及EAC组(66.7%)以(+)为主,差异无统计学意义(P0.05),与肠化组(91.7%)以()为主显著不同(P0.05)。SOX2在Barrett食管三组中的阳性率均为100%,显著高于EAC组(28.6%)(P0.05)。SOX2以(++)表达方式在胃底组(95.7%)及贲门组(74.3%)中差异无统计学意义(P0.05);显著高于肠化组(50%)和EAC组(50%)(P0.05)。SOX2和CDX2的表达在肠化型Barrett食管中呈负相关(P0.05),在贲门组、胃底组、EAC组中无明显相关(P0.05)。结论短段贲门型Barrett食管中CDX2的阳性率不高,可能只是一种柱状上皮化生,与EAC的关系不大;CDX2在鳞状上皮向特殊肠上皮化生转化过程中发挥重要作用,SOX2的沉默促进EAC发生。     

Loss of heterozygosity of APC and DCC tumor suppressor genes in human sporadic colon cancer

We examined 36 cases of human sporadic colon carcinoma and corresponding normal tissue samples to evaluate loss of heterozygosity at the APC and DCC tumor suppressor genes loci using restriction fragment length polymorphism polymerase chain reaction and variable nucleotide tandem repeat analysis. Observed informativity was 83% for APC and 75% for DCC. DNA from 6 (20%) of 30 informative tumors exhibited loss of heterozygosity at the APC locus. Loss of heterozygosity at the DCC locus was observed in 7 (26%) of 27 informative tumor DNAs. Our results support the view that malignant progression is a consequence of more than one genetic change and suggest that inactivation of APC and DCC genes plays a role in a multistep process of colon tumor progression. Received: 7 August 1998 / Accepted: 15 December 1998     

Expression of MUC1 and MUC2 mucin gene products in Barrett's metaplasia, dysplasia and adenocarcinoma: an immunopathological study with clinical correlation

AIMS: Changes in the histochemical characteristics of the surface epithelial mucins is the hallmark of Barrett's metaplasia. The study investigated the pattern of expression of MUC1 and MUC2 mucin gene products in Barrett's metaplasia, dysplasia and adenocarcinoma as possible indicators of increased malignant potential. METHODS AND RESULTS: Tissue sections from 51 patients with Barrett's intestinal metaplasia, nine with dysplasia (three indefinite) and 28 resected adenocarcinomas were stained with monoclonal antibodies to MUC1 and MUC2. The majority of the patients were men (70/88, 80%) who were treated over a period of 3 years. None of the patients with dysplasia or carcinoma were under surveillance at the time of presentation. All 51 biopsies with Barrett's metaplasia expressed MUC2 and MUC1 was consistently absent. Neither MUC1 or MUC2 were expressed in the dysplastic epithelium whether in its pure form (6/6) or when associated with carcinoma (26/28) (P < 0.005). Three biopsies which were initially classified as high-grade dysplasia expressed MUC1 and these turned out to be carcinomas on further investigations. MUC1 was also expressed in 12/28 (43%) of the adenocarcinomas and majority of these were poorly differentiated stage 3 tumours (P < 0.05). MUC2 was only positive in mucin-secreting carcinomas (4/28; 14%) irrespective of the tumour stage. CONCLUSION: Despite the large number of patients with Barrett's metaplasia and carcinoma, very few patients presented with dysplasia, implying that Barrett's oesophagus is a silent disease in the community presenting late as carcinoma. The study has demonstrated aberrant expression of MUC2 (an intestinal mucin) in Barrett's metaplasia and this expression is lost when the cells become dysplastic. The lack of MUC1 in dysplastic epithelium and its expression in carcinoma could be utilized as a marker which could differentiate dysplasia from carcinoma in mucosal biopsies. Furthermore, expression of MUC1 in advanced stage oesophageal cancers (as in breast cancer) suggests an unfavourable prognosis.     

Expression of survivin, p53, and caspase 3 in Barrett's esophagus carcinogenesis

The regulation of apoptosis, as a distinctive form of programmed cell death, in multistep Barrett's esophagus (BE) carcinogenesis is poorly understood. The aim of this study was to investigate, in the intestinal metaplasia-dysplasia-carcinoma sequence, the role of survivin, an inhibitor of apoptosis; the p53 protein, a tumor suppressor gene involved in cell cycle control; and caspase 3, a protease-inducing apoptosis and inhibited by survivin. Immunohistochemical expression was tested in 40 cases of BE, including 11 low-grade and 19 high-grade dysplasias (HGD), and samples were obtained from 40 surgical specimens of esophagectomy performed for HGD or Barrett's adenocarcinoma. To define the deregulation time of the proteins, overexpression was evaluated in relation to the proliferative and/or maturative compartment. In BE, cytoplasmic expression of survivin and caspase 3 (100% of cases) was significantly higher than expression of p53 (25%). The latter increased with increasing grade of dysplasia. In BE, the expression of survivin, p53, and caspase 3 mainly involved the proliferative compartment, whereas in LGD and HGD, the 3 proteins were coexpressed in both proliferative and maturative compartments. These results indicate that survivin overexpression is an early event in the proliferative compartment of BE, preceding both p53 accumulation and dysplastic changes. Cytoplasmic survivin location may indicate an initial antiapoptotic, more than proliferative, role in the early phases of Barrett carcinogenesis. Expression of caspase 3 in BE and dysplasia may be ascribed to accumulation of the nonactivated form, as the antibody used detects both cleaved and uncleaved caspase 3.     

Molecular analysis of the TP53 gene in Barrett's adenocarcinoma

The TP53 gene is the most frequently mutated gene in human cancers. Barrett's esophagus provides an excellent model by which to understand the genetic events that lead from dysplasia to cancer. We screened for mutations in the TP53 gene by a combination of denaturing gradient gel electrophoresis and DNA sequencing in ten cases of adenocarcinoma arising in Barrett's mucosa. We have identified missense mutations in five of the ten samples, three transitions (R282W, G245S, R248W) and two transversions (E286Q and C176F). In one case we have analyzed biopsy specimens taken from the same site, one year before the patient developed an intra mucosal carcinoma. The mutation that was identified in this high grade dysplastic area was identical to that detected in the cancer. This would suggest TP53 mutations occur as an early genetic event in the development of Barrett's adenocarcinoma. © 1996 Wiley-Liss, Inc.     

A comparison of conventional cytology, DNA ploidy analysis, and fluorescence in situ hybridization for the detection of dysplasia and adenocarcinoma in patients with Barrett's esophagus

New detection methods with prognostic power are needed for early identification of dysplasia and esophageal adenocarcinoma (EA) in patients with Barrett's esophagus (BE). This study assessed the relative sensitivity and specificity of conventional cytology, DNA ploidy analysis with digital image analysis (DIA), and fluorescence in situ hybridization (FISH) for the detection of dysplasia and adenocarcinoma in endoscopic brushing specimens from 92 patients undergoing endoscopic surveillance for BE. FISH used probes to 8q24 (C-MYC), 9p21 (P16), 17q12 (HER2), and 20q13. Four-quadrant biopsies taken every centimeter throughout visible Barrett's mucosa were used as the gold standard. The sensitivity of cytology, DIA, and FISH for low-grade dysplasia was 5%, 5%, and 50%, respectively; for high-grade dysplasia (HGD), 32%, 45%, and 82%, respectively; and for EA, 45%, 45%, and 100%, respectively. FISH was more sensitive (P < .05) than cytology and DIA for low-grade dysplasia, HGD, and EA. The specificity of cytology, DIA, and FISH among patients (n = 14) with tissue showing only benign squamous mucosa was 93%, 86%, and 100% (P = .22), respectively. All patients with a polysomic FISH result had HGD and/or EA within 6 months (n = 33). There was a significant difference between FISH categories (negative, 9p21 loss, gain of a single locus, and polysomy) for progression to HGD/EA (P < .001). These findings suggest that FISH has high sensitivity for the detection of dysplasia and EA in BE patients, with the power to stratify patients by FISH abnormality for progression to HGD/EA. Additional studies are needed to further evaluate the clinical use of FISH.     

Role of epigenetic alterations in the pathogenesis of Barrett's esophagus and esophageal adenocarcinoma

Barrett's esophagus, a pre-malignant condition that can lead to esophageal adenocarcinoma, is characterized by histological changes in the normal squamous epithelium of the esophagus. Numerous molecular changes occur during the multistage conversion of Barrett's metaplasia to dysplasia and frank adenocarcinoma. Epigenetic changes, especially changes in DNA methylation are widespread during this process. Aberrant DNA methylation has been shown to occur at promoters of tumor suppressor genes, adhesion molecules and DNA repair genes during Barrett's esophagus. These epigenetic alterations can be used as molecular biomarkers for risk stratification and early detection of esophageal adenocarcinoma. We also show that genome wide analysis of methylation surprisingly reveals that global hypomethylation and not hypermethylation is the dominant change during Barrett's metaplasia. The transformation of Barrett's esophagus to frank adenocarcinoma is in turn characterized by much smaller wave of selective promoter hypermethylation. These studies reveal many novel, potential targets for new therapies and illustrate the utility of incorporating these epigenetic changes as biomarkers during endoscopic surveillance interval for patients with Barrett's esophagus.     

Mutation analysis of the p53, APC, and p16 genes in the Barrett's oesophagus, dysplasia, and adenocarcinoma.

AIMS: To study the loss of heterozygosity and the presence of mutations at the p53, p16/CDKN2, and APC genes in Barrett's oesophagus, low grade dysplastic oesophageal epithelium, and adenocarcinoma of the oesophagus; to relate the presence of alterations at these genes with the progression from Barrett's oesophagus to adenocarcinoma. METHODS: DNA was extracted from paraffin blocks containing tissue from Barrett's oesophagus (12 samples), low grade dysplasia (15 cases), and adenocarcinoma (14 cases). Loss of heterozygosity (LOH) at the p53, p16, and APC genes was determined by comparing the autoradiographic patterns of several microsatellite markers between the normal tissue and the malignant tissue counterpart. SSCP was used to determine the presence of mutations at p53 (exons 5 to 8), p16 (exon 2), and APC. Homozygous deletion of the p16 gene was defined through polymerase chain reaction followed by Southern blot. RESULTS: LOH at the p53, p16, and APC genes was not observed in Barrett's oesophagus without dysplasia, and increased to 90% (p53), 89% (p16), and 60% (APC) in the adenocarcinomas. The p53 gene was mutated in only two adenocarcinomas (codons 175 and 245). In one case a mutation at the APC gene (codon 1297) was found. No patient had mutation at the second exon of p16. However, this gene was homozygously deleted in three of the 12 adenocarcinomas. CONCLUSIONS: The tumour suppressor genes p53, p16, and APC are often deleted in adenocarcinomas derived from Barrett's oesophagus. Mutations at these genes are also found in the adenocarcinomas, including the homozygous deletion of the p16 gene. However, the absence of genetic alterations in the Barrett's oesophagus and the low grade dysplastic epithelia suggest that mutations at these genes develop later in the progression from Barrett's oesophagus to adenocarcinoma.     

Use of twins in search for tumor suppressor genes

A new approach is applied in the mapping of tumor suppressor genes: analysis of loss of heterozygosity (LOH) in concordant tumors of monozygotic and dizygotic twins. The method relies on recognition of genome locations undergoing loss in both twins in a high proportion of the set of all twin pairs examined. The method effectively pinpoints, and excludes, the loci of potential tumor suppressor genes. With the help of a high density linkage map any such candidates can be placed within a narrow region of a chromosome arm and perhaps matched with known genes. The analysis of the Swedish Twin Registry has shown a clear genetic component for breast cancer. We have identified mono- and dizygotic twins concordant for breast cancer and collected the pathology specimens. Tumor and normal tissue was microdissected and microsatellite analysis carried out to test for allelic loss (LOH) in entirely new and putative chromosomal loci in this cancer. It can be calculated that using only six pairs of informative monozygotic twins, a locus can be incriminated with a high probability. Using increasingly dense markers and search for homozygous deletions, it should be possible to map one or more candidates for breast cancer. Environ. Mol. Mutagen. 30:231–239, 1997. © 1997 Wiley-Liss, Inc.     

Allelic loss involving the tumor suppressor genes APC and MCC and expression of the APC protein in the development of dysplasia and carcinoma in Barrett esophagus

Samples of Barrett metaplastic specialized epithelium (SE), low-grade dysplasia (LGD), high-grade dysplasia (HGD), and invasive adenocarcinoma (CA) derived from 36 esophagectomy specimens were studied for loss of heterozygosity (LOH) in APC and MCC and for expression of APC protein. Of 18 cases that were heterozygous (informative) for APC, LOH was found in none of 14 SE samples, 2 of 8 LGD samples, 3 of 11 HGD samples, and 5 of 17 CA samples. Immunohistochemically, markedly reduced expression of APC protein (< 50% positive cells) was found in 3 of 19 HGD samples and 4 of 35 CA samples but not in SE or LGD samples. Of 17 cases informative for the MCC gene, LOH was detectable in 1 of 14 SE samples, none of 7 LGD samples, none of 9 HGD samples, and 4 of 16 CA samples. Allelic loss of APC and/or loss of APC protein expression occurs earlier in the metaplasia-dysplasia-carcinoma sequence in Barrett esophagus than LOH in the MCC gene. The determination of alterations at APC or MCC would be of limited importance for the surveillance of patients with Barrett esophagus.     

Glucocorticoid receptor and serum‐ and glucocorticoid‐induced kinase‐1 in esophageal adenocarcinoma and adjacent Barrett's esophagus

Barrett's esophagus (BE) is a consequence of gastroesophageal reflux disease and is predisposed to esophageal adenocarcinoma (EAC). EAC is an exemplar model of inflammation‐associated cancer. Glucocorticoids suppress inflammation through glucocorticoid receptor (GR) and serum‐ and glucocorticoid‐induced kinase‐1 (Sgk1) expressions. Therefore, we immunolocalized GR and Sgk1 in EAC and the adjacent BE tissues and studied their association with clinical disease course in 87 patients with EAC who underwent surgical resection (N = 58) or endoscopic submucosal dissection (N = 29). Low GR and Sgk1 expressions in adjacent BE tissues were associated with adverse clinical outcomes (P = 0.0008 and 0.034, respectively). Patients with low Sgk1 expression in EAC cells exhibited worse overall survival (P = 0.0018). In multivariate Cox regression analysis, low GR expression in the adjacent nonmalignant BE tissues was significantly associated with worse overall survival (P = 0.023). The present study indicated that evaluation of GR and Sgk1 expressions in both the EAC cells and adjacent nonmalignant BE tissues could help to predict clinical outcomes following endoscopic and surgical treatments. In particular, the GR status in BE tissues adjacent to EAC was an independent prognostic factor.     

肝原发性淋巴瘤抑制基因杂合性缺失分析

目的 探讨肿瘤抑制基因杂合性缺失(LOH)在肝原发性淋巴瘤(PHL)发生中的作用。方法 采用显微组织切割术从石蜡组织切片中提取DNA,在PCR基础上进行毛细管电泳DNA测序,对9例手术切除的PHL标本进行了视网膜母细胞瘤1基因(Rb1)、腺瘤性息肉病基因(APC)、结直肠癌突变基因(MCC)、结直肠癌缺失基因(DCC)等4种肿瘤抑制基因(TSGS)LOH检测。结果 B细胞系PHL中APC基因LOH发生率为50．0％,其余3种基因未检测到LOH,T细胞系PHL中LOH发生率为APC(33．3％)、Rb1(50．0％)、DCC(20．0％)、MCC(0．0)。结论 PHL中有较高频的APC和．Rb1基因LOH,提示在PHL的形成过程中APC和Rb1基因的变异起重要作用。     

The relationship of endocrine cells, dysplasia and carcinoembryonic antigen in Barrett''s mucosa to adenocarcinoma of the oesophagus

This study was undertaken to assess the prevalence and characteristic hormonal profile of endocrine cells in Barrett's mucosa and to determine to what extent this profile was shared by endocrine cells of adenocarcinomas arising therefrom. In addition, lower oesophageal carcinomas, not associated with columnar metaplasia, were examined to see if they exhibited a different hormonal profile. The patients studied comprised 43 who had had multiple oesophageal biopsies. 35 who had had oesophagogastric resection for adenocarcinoma arising in Barrett's mucosa and 26 in whom the resection showed no metaplastic epithelium adjacent to tumour. Argyrophil cells were present in 90% of biopsies and resections of Barrett's mucosa combined, irrespective of the histological type of metaplastic epithelium. By immunocytochemistry the most frequently identified substance in mucosal endocrine cells was serotonin (82%) followed by somatostatin (54%), secretin (22%) and pancreatic polypeptide (17%). Gastrin, bombesin, cholecystokinin, ACTH and substance P were not identified in metaplastic mucosa in any case. The difference in expression of serotonin by endocrine cells of tumours arising in Barrett's mucosa (31%) and those not (3.8%) was statistically significant (P less than 0.0186). Carcinoembryonic antigen (CEA) was demonstrated in 60% of oesophageal carcinomas, both endocrine positive and endocrine negative. Focal CEA expression was seen in 4.6% of biopsies and 14% of Barrett's mucosa adjacent to tumour. These results indicate a higher prevalence of endocrine cells in Barrett's mucosa than hitherto documented and suggest that serotonin may be a useful marker in distinguishing between primary oesophageal and putative gastric cancers at the gastro-oesophageal junction. The identification of CEA in oesophageal columnar epithelium is of little value in predicting the development of malignancy.     

肝细胞腺瘤肿瘤抑制基因杂合性缺失分析

目的 探讨肿瘤抑制基因杂合性缺失(LOH)在肝细胞腺瘤(HCA)发生中的可能作用。方法 采用显微组织切割术从石蜡组织切片中提取DNA，在聚合酶链式反应(PCR)基础上进行毛细管电泳DNA测序，对12例手术切除的HCA标本进行了视网膜母细胞瘤1基因(Rb1)、腺瘤性息肉病基因(APC)、结直肠癌突变基因(MCC)、结直肠癌缺失基因(DCC)4种肿瘤抑制基因(TSGs)LOH检测。结果 4种肿瘤抑制基因LOH发生率分别为Rb1(2／7，28．5％)、APC(1／10，10．0％)、MCC(0／5，0％)、DCC（0／6，0％)。发生LOH的3例HCA无1例在手术切除后出现肿瘤复发。结论 HCA的LOH是较为少见的分子事件，Rb1和APC基因的LOH可能在少数HCA的发生中起一定作用，但仍不足以支持HCA是肝细胞癌的癌前病变。     

Acidic fibroblast growth factor is progressively increased in the development of oesophageal glandular dysplasia and adenocarcinoma

AIMS: To determine by immunohistochemistry and amplification of cDNA the relationship between fibroblast growth factor (FGF) expression and progressive changes in Barrett's oesophagus associated with oesophageal adenocarcinoma (OA). The FGFs are potent mitogens that possess angiogenic properties and the capability to regulate growth and differentiation of various cell types. They have also been implicated in the development and progression of numerous solid tumours, including some carcinomas of the aerodigestive tract, such as nasopharyngeal carcinoma and pancreatic adenocarcinoma. MATERIAL AND RESULTS: We studied the expression of the two prototypic FGFs, acidic FGF (FGF-1) and basic FGF (FGF-2), in OA and OA precursor lesions, including intestinal metaplasia (IM), low-grade dysplasia (LGD) and high-grade dysplasia (HGD). Fresh tissue from 10 OAs and four associated HGDs was available for the determination of FGF-1 and FGF-2 mRNA expression accomplished by the PCR amplification of cDNA. Using immunohistochemistry, we studied the expression of the FGF-1 and FGF-2 proteins in archival, paraffin-embedded tissue that was available from 17 oesophageal resection specimens that included OAs and OA precursor lesions. As compared to gastric fundic mucosal controls, OAs and HGDs showed significantly enhanced expression of FGF-1 mRNA and protein. IMs and LGDs showed significantly lesser degrees of FGF-1 immunoreactivity that were not increased over controls. In contrast, both the overall percentage of FGF-2-reactive OAs and the overall FGF-2 protein expression, assessed using an immunoreactivity score, are comparable to FGF-2 expression in controls. CONCLUSIONS: It appears that FGF-2 is ubiquitously expressed in OA and in normal oesophageal and gastric mucosa while significant FGF-1 expression is essentially restricted to HGD and OA. Our data also suggest that FGF-1 is sequentially upregulated in the progression from metaplasia to dysplasia and adenocarcinoma.     

Distinction between intestinal metaplasia in the cardia and in Barrett's esophagus: the role of histology and immunohistochemistry

Intestinal metaplasia in Barrett's esophagus (BIM) is a precancerous condition, whereas the carcinogenic potential of intestinal metaplasia of the cardia (CIM) is uncertain. Although clinically important, histological distinction between both conditions by endoscopic biopsies is considered problematic. In the present study, 4-mm samples of BIM (n=31) and CIM (n=9) were selected from esophagectomy specimens that had been resected for esophageal cancer. Slides were coded and stained with hematoxylin and eosin (H&E), Alcian blue-periodic acid-Schiff (PAS), cytokeratins (CK) 7 and 20, and CD10, which labels the intestinal brush border. The predictive value of these stains for the recognition of BIM and CIM was evaluated independently by two senior pathologists. With the use of H&E-stained slides exclusively, BIM samples were categorized correctly in 93.5% and 83.9% of cases (pathologists 1 and 2, respectively), and CIM samples, in 100% and 88.9% of cases. Alcian blue-PAS-positive goblet cells were identified by both investigators in all BIM and CIM samples. BIM-typical CK 7 and 20 immunostaining pattern was identified in 90.3%/83.9% of BIM but only in 11.1%/11.1% of CIM. CD10-positive brush border was present in 32.3%/25.8% of BIM and in 88.9%/88.9% of CIM. When HE-stained slides and immunohistologically stained slides were used together for tissue recognition, BIM were categorized correctly in 90.3%/80.6% of cases, and CIM, in 88.9%/88.9% of cases. In conclusion, BIM and CIM can be usually distinguished on the basis of HE sections. CK 7 and CK 20 expression pattern analysis discriminates correctly between BIM and CIM in the majority of cases. CD10-positive intestinal brush border is present in the majority of CIM but only in a minority of BIM. However, immunohistochemical investigations could not improve the diagnostic accuracy of HE histology alone.     

Database of mutations in the p53 and APC tumor suppressor genes designed to facilitate molecular epidemiological analyses

Germline and somatic mutations in the p53 and APC genes contribute to neoplasia. The patterns of these and other acquired mutations in cancers reflect environmental mutagens and endogenous factors that contribute to carcinogenesis. Herein, we describe a database of almost 2,300 mutations in the p53 and APC genes published until September 1, 1993. In addition to cataloging the mutations, multiple fields of information have been added to facilitate future molecular epidemiological analyses of human cancer. The accuracy of the database has been checked by the present authors and, by soliciting feedback from the original corresponding authors. The strengths and limitations of the primary literature are discussed. © 1996 Wiley-Liss, Inc.     

Role of cytology in the diagnosis of Barrett's esophagus and associated neoplasia

We studied 327 consecutive paired esophageal biopsies and brushing specimens obtained during the same endoscopic session to evaluate the role of cytology for the diagnosis of Barrett's esophagus (BE) and/or surveillance for associated dysplasia. A diagnosis of BE was based on the cytologic presence of goblet cells. Cases were reviewed and categorized into: 1) benign esophageal lesions (125 cases), with 48 cases of Candida (32 cases diagnosed by both techniques and 16 diagnosed only by cytology), 3 cases of herpes simplex with only 1 case diagnosed by cytology, and 74 cases of inflammation and/or repair; 2) benign BE (141 cases), with 74 cases (52%) diagnosed by both techniques, 11 cases by cytology only (8%), and 56 cases (40%) by histology only; 3) low-grade dysplasia (LGD, 30 cases), with 5 cases (17%) diagnosed with both specimens, one case (3%) by cytology only, and 24 cases (80%) by histology only; 4) high-grade dysplasia (HGD, 10 cases), with 8 cases (80%) diagnosed with both specimens, 1 case (10%) by cytology, and 1 case (10%) by histology; and 5) carcinomas (23 cases), with 20 cases (87%) diagnosed with both specimens, 2 cases (9%) by cytology only, and 1 case (4%) by histology only. Our results support the high degree of diagnostic accuracy of cytology for the diagnosis of Barrett's-associated HGD and/or carcinoma, and moderate sensitivity for BE.     

Loss of heterozygosity during the development and progression of differentiated adenocarcinoma of the stomach

In a recent allelotypic analysis of differentiated adenocarcinoma of the stomach, loss of heterozygosity (LOH) was found frequently on chromosomes 2q, 4p, 5q, 6p, 7q, 11q, 14q, 17p, 18q, and 21q. To clarify the sequence of these chromosomal losses during gastric carcinogenesis, microsatellite analysis of the chromosome arms described above was performed in 25 early and 29 advanced differentiated adenocarcinomas of the stomach. LOH on these chromosome arms fell within a range of 20–50 per cent. On 4p, 7q, 14q, 17p, and 21q, LOH was detected at a similar frequency in both early and advanced carcinomas, while LOH on 2q, 5q, 6p, 11q, and 18q was observed more than twice as frequently in advanced than in early lesions. Mean fractional allelic losses (FALs) were 0·221 in early and 0·413 in advanced carcinomas, representing a significant difference (P<0·05). These results suggest that LOH on 4p, 7q, 14q, 17p, and 21q is a relatively early event, while LOH on 2q, 5q, 6p, 11q, and 18q typically accumulates during the progression of gastric carcinogenesis. © 1998 John Wiley & Sons, Ltd.