| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Short Communications |
From the International Agency for Research on Cancer;*
the Fédération des Spécialités
Digestives
and the Laboratoire
d’Anatomie Pathologique,
Hôpital
Edouard Herriot, Lyon, France
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
ADCE occur in the distal part of the esophagus and develop from Barrett’s mucosa, a glandular metaplasia of the squamous epithelium that can vary in height from a few millimeters to a few centimeters. There is evidence that the metaplastic glandular cells are hybrid cells, expressing cytokeratins (CKs) of both squamous (CK4 and 13) and glandular (CK8 and 19) origin2 and having ultrastructural features of both squamous and glandular cells.3 Furthermore, they have been shown to constantly express CK7, in contrast to intestinal metaplastic cells of the cardia mucosa, which never do.4 Barrett’s mucosa is often associated with chronic gastroesophageal acid reflux. However, it can also occur in combination with chronic biliary alkaline reflux as well as in the absence of reflux.5 Factors predisposing to Barrett’s mucosa are not well documented. Recent evidence suggests that expression of certain polymorphic forms of glutathione-S-transferase P1 may be a genetic susceptibility factor for developing Barrett’s mucosa.6 Barrett’s mucosa is a very common lesion that is thought to occur in >10% of the general population in the United States and is associated with a 10-fold increase in the risk of developing ADCE.7
The cardia is the anatomical region corresponding to the transition between esophagus and stomach. It cannot be identified at the macroscopic level. At the microscopic level, the cardia is characterized by a thin mucosa with clear glandular cells, without any acid-secreting cells. It ranges in height from 1 to 5 mm, with an increase in size with age. The term "ADCC" applies to tumors located exclusively in the region of the cardia. However, it has not been established whether these tumors originate from the true cardial mucosa rather than from the neighboring upper fundic mucosa. Intestinal metaplasia can be observed within the cardia, in particular in connection with chronic inflammation. However, there is no clear evidence that this metaplasia predisposes to development of ADCC.
In many studies, it has been common to group ADCC and ADCE as "adenocarcinomas of the esophagogastric junction," and such a grouping may have precluded the identification of specific risk factors other than reflux. The role of tobacco consumption is controversial.8-11 Obesity and anti-hypertensive drugs relaxing the cardial sphincter are considered as indirect risk factors as they may favor chronic gastroesophageal reflux. A high intake of calories, fat, and iron has also been implicated.12,13 In contrast, high ingestion of fiber, niacin, vitamin B6, iron, and zinc8,10,12 has been suggested to protect against tumor development.
At the molecular level, mutation of the tumor-suppressor gene TP53 is the most frequent alteration identified in carcinomas of the esophagogastric junction. In ADCE, TP53 mutations have been detected in 58% of the cases (M. Olivier, personal communication, IARC TP53 mutation database, R4 version). The most frequent type of mutation is C to T transition at a dipyrimidine repeat (CpG) (50%). Mutations are thought to occur early during tumorigenesis, because they are sometimes detectable in Barrett’s mucosa without dysplasia.8,14 Only three retrospective studies have analyzed TP53 mutations in ADCC.15 Together, they show a mutation prevalence of 50%, with a high proportion of transitions at CpG (40%).16,17 In this study, we have used strict criteria to collect at the time of surgery well-characterized cases of ADCC or ADCE. Tumors were classified as ADCE when they predominantly involved the lower part of the esophagus and/or a Barrett’s mucosa could be identified at the macroscopic or at the microscopic level on the surgical samples.18 Tumors were classified as ADCC when they involved the esophagogastric junction, predominantly invading the gastric part, or when they developed at <2 cm from the esophagogastric junction. Our group of ADCE correspond to type I of the classification proposed by Siewert and Stein,19 whereas the tumors we defined as ADCC regroup type II (true cardia tumors) and to type III (tumors from the subcardia region) of this same classification. All tumors were analyzed for the presence of mutations in TP53 and for amplification of MDM2, a gene that encodes a protein involved in the control of p53 function and that has been found to be amplified in some tumors in which TP53 is not mutated. The profile of expression of three CKs (4, 7, and 13), which show specific cell localization, has also been compared. We report that the two groups of patients showed differences in several individual and clinical parameters (sex ratio, associated neoplasms, tobacco smoking), in the prevalence of TP53 mutations and MDM2 amplification, and in the patterns of cytokeratin expression.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Tumor tissues were collected at the time of surgery from patients recruited at the E. Herriot Hospital (Lyon, France). The criteria for inclusion in the study were: 1) the presence of a primary adenocarcinoma of the esophagogastric junction; 2) no primary treatment; and 3) signature of an informed consent form. Most tissue samples were obtained at surgery. However, for ADCE, biopsies were also included in the study after endoscopic detection of tumors of the lower part of the esophagus within a Barrett’s mucosa. ADCC was defined as a tumor centered close to the esophagogastric junction (<2 cm), predominantly invading the stomach without any evidence of a long or a short segment of Barrett’s. Clinical records were reviewed to collect information on the patients’ past medical histories and their tobacco smoking habits. The tissue and data collection protocol was approved by the local and institutional ethical committees.
DNA Extraction
DNA was isolated from microdissected tissue. Tissues were fixed in 10% buffered formalin and embedded in paraffin. Serial 4-µm-thick sections were cut from paraffin blocks. For each sample, morphological assessment was performed on one 4-µm tissue section stained with hematoxylin and eosin. The sections after this one were used for DNA extraction. Briefly, the slides were rehydrated. The areas of interest were selected by analysis of the stained slide and then scraped from the slide using a scalpel blade. The scraped material was transferred into an Eppendorf tube containing 50 µl of extraction buffer (10 mmol/L of Tris-HCl, pH 9, 20 mg/ml of proteinase K, 0.1% Nonidet P-40). Samples were incubated for 3 days at 56°C, with addition of 2 µl of proteinase K (20 mg/ml) twice a day. Proteinase K was then inhibited by incubation at 95°C for 10 minutes.
Immunohistochemistry
Tissue sections were deparaffinized using standard protocols. After inactivation of endogenous peroxidases (30 minutes in 0.3% H2O2/methanol), slides were rehydrated, incubated with a blocking solution (phosphate-buffered saline containing 5% nonfat milk powder) and exposed overnight at 4°C to the primary antibody. For CK and mdm2 protein labeling, this sequence of treatments was preceded by an antigen-unmasking procedure (3 x 5 minutes in a microwave oven for CK4, 7, and 13, and 10 minutes in a pressure cooker for mdm2; Vector Laboratories Inc., Biosys S.A., Compiègne, France). The following primary antibodies were used: CM1 (purified rabbit IgG anti-human p53, 1/500; Novocastra Laboratories Ltd., Newcastle, UK), mdm2(Ab-1) (monoclonal antibody against human mdm2, clone IF2, 1/100; Calbiochem, San Diego, CA), CK4 (monoclonal antibody, clone 6B10, 1/100; Novocastra Laboratories Ltd.), CK7 (monoclonal antibody, clone AE1/AE3, 1/100; DAKO, Copenhagen, Denmark), and CK13 (monoclonal antibody, clone KS-1A3, 1/50; Novocastra Laboratories Ltd.). Incubation with the relevant secondary antibodies (either anti-mouse or an anti-rabbit biotinylated IgG, 1/200, Vectastain Elite-ABC kit; Vector Laboratories Inc.) for 30 minutes at room temperature was followed by streptavidin-peroxidase (1/50, 30 minutes at 37°C). Peroxidase activity was detected with a diaminobenzidine-based detection kit (Vector Laboratories, Inc.) and sections were counterstained with Mayer’s hematoxylin before dehydration and mounting.
TP53 Mutation Analysis
TP53 exons 4 to 9 were analyzed by temporal temperature gradient
electrophoresis using the DGene system (BioRad, Richmond, CA) and the
primers described by Hamelin and colleagues20
(exons 5, 7, and 8) and Guldberg and colleagues21
(exons
4, 6, and 9). DNA was amplified in a DNA thermocycler (Perkin Elmer,
Norwalk, CT) in a 50-µl reaction mixture containing 5 µl of genomic
DNA, 20 pmol of sense and anti-sense primers, 200 µmol/L of each
dNTP, 1x amplification buffer, 1 X Q solution and 0.5 µl (2.5 U) of
Taq polymerase (HotStarTaq DNA polymerase; Qiagen, Hilden,
Germany). Polymerase chain reaction (PCR) conditions were: 15 minutes
at 95°C followed by 35 cycles at 95°C (1 minute), 56°C (exons 5
proximal, 8, and 9) or 62°C (exons 4a, 4b, 5 distal, 6, and 7) (1
minute), 72°C (90 seconds). The reaction was ended by a 10-minutes
extension at 72°C. Heteroduplex formation was induced by denaturation
for 10 minutes at 98°C, followed by 30 minutes at the respective
annealing temperature (56°C or 62°C). Temporal temperature gradient
electrophoresis was run at 130V at temperatures optimized for each DNA
fragment (exon 4p, 4d, 6, and 9: 58 to 70°C; exon 5p: 56 to 70°C;
exon 5d: 63 to 70°C; exon 7: 59 to 70°C; exon 8: 53 to 67°C). A
negative control (wild-type sample) and positive control (known mutant)
were included in each analysis. Samples that showed additional and/or
abnormal bands were re-amplified from genomic DNA and a second temporal
temperature gradient electrophoresis was performed. If confirmed,
mutant alleles were cut from this second gel, re-amplified using the
same primers, and analyzed by direct sequencing after asymmetric PCR
amplifications as previously described.20,22
Two cases
with positive p53 immunostaining (>50%) did not show reproducible
patterns of abnormal bands in temporal temperature gradient
electrophoresis (case 12, Table 1
, and
case 3, Table 2
). In these two cases,
mRNA was isolated from frozen biopsies, and cDNA was prepared and
tested using the yeast functional assay as described by Flaman et
al.23
Positive colonies were sequenced using the ABI PRISM
310 Genetic analyzer (Perkin Elmer Biosystems, Foster City, CA).
|
|
Differential PCR was performed as previously described24 with the following modifications: 5 µl of template DNA was amplified in 50 µl of a reaction mixture containing 20 pmol each of sense and anti-sense primers for MDM2 and for the dopamine D2 receptor gene DRD2 (used as a reference), 200 µmol/L of each dNTP, 1x amplification buffer, 1 X Q solution and 0.5 µl (2.5 U) of HotStarTaq DNA Polymerase (Qiagen). PCR conditions were: 15 minutes at 95°C, followed by 27 cycles at 95°C for 45 seconds, 55°C for 45 seconds, and 72°C for 1 minute with a final extension at 72°C for 5 minutes. The primers were as follows: 5'-GAGGGCTTTGATGTTCCTGA-3' (sense) and 5'-GCTACTAGAA GTTGATGGC-3' (anti-sense) for MDM2, and 5'-CCACTGAATCTGTCCTGGTATG-3' (sense) and 5'-GTGTGGCATAGTAGTTGTAGTGG-3' (anti-sense) for human DRD2. PCR products were electrophoresed on 7.5% polyacrylamide gels stained with ethidium bromide, photographed, and the films were analyzed by scanning densitometry (GS-670; BioRad, Hercules, CA). An MDM2/DRD2 ratio of 2.5 or above was regarded as indicative of MDM2 amplification and a ratio between 2 and 2.5 was regarded as compatible with MDM2 amplification.
Statistical Evaluations
Frequency tables of independent variables were evaluated for statistical significance by Pearson’s chi-square test.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Twenty-six cases of ADCC and 28 cases of ADCE were collected
between 1995 and 1999 (Tables 1 and 2)
. In one case, a tumor was
classified as ADCE on the basis of the previous diagnosis on biopsy of
a Barrett’s mucosa that was no longer detectable at surgery. None of
the patients had received chemotherapy or radiotherapy before biopsy or
surgery.
The mean age of patients was 62.1 ± 13.6 years (range, 25 to 82 years) for ADCC and 68.1 ± 9 years (range, 50 to 82 years) for ADCE. The group of ADCC patients investigated included 17 men and nine women (male/female ratio of 0.65), whereas the ADCE patients were almost exclusively males (27 males and one female; male/female ratio 0.97). Despite the short follow-up period for some of the patients, medical records revealed that five of the ADCC patients had additional tumors. Three women developed a breast adenocarcinoma either before (19 years, patient 42; 2 years, patient 46) or after (3 years, patient 33) diagnosis of ADCC. One of these patients (patient 46) also developed a malignant melanoma 10 years before ADCC. One man (patient 38) had an adenocarcinoma of the intestine 10 years before ADCC and another (patient 29) presented a pleomorphic adenoma of the parotid 5 years before ADCC. Among the ADCE patients, only one patient had a history of a previous cancer (a squamous cell carcinoma of head and neck in a male patient who was a heavy smoker and alcohol drinker). The available data do not suggest the existence of a familial history of cancer in these patients.
Reliable information on tobacco smoking was available for 15 patients with ADCC and for 14 patients with ADCE. Six of these 15 ADCC patients (40%) and 10 of the 14 ADCE patients (71.5%) were regular smokers (>5 packs-year).
The mean size of the 22 resected ADCE (4.5 cm; range, 1 to 8 cm), was not significantly different from that of the ADCC (5.5 cm; range 1.2 to 12 cm). However, the tumors in the two groups differed in their stage distribution with more frequent lymph-node involvement in the ADCC group than in the ADCE group. According to the TNM classification, four ADCE were stage T1N0 (18%), three were T2N0 (13.5%), seven were T3N0 (32%), and eight were T3N1 (36.5%). In comparison, one ADCC was stage T1N0 (4%), one was T2N0 (4%), four were T3N0 (15.5%), and 20 were T3N1 (77%).
TP53 Mutations
TP53 mutations were detected in 8 of 26 (31%) ADCC and in 14 of
28 (50%) ADCE (Tables 1 and 2)
. In two cases of ADCE, two mutations
were detected. The mutation spectrum showed that 5 of 8 (62.5%) of the
ADCC mutations and 5 of 16 (31%) of the ADCE mutations were C to T
transitions at CpG sites (Table 3)
. The
concordance between TP53 mutation status and p53 overexpression, as
detected by immunohistochemistry using the CM-1 antibody, was 92% in
both tumor types (Tables 1 and 2)
.
|
In ADCC, expression of the mdm2 protein (detectable by
immunohistochemistry in at least 10% of the tumor cells) was found in
50% (13 of 26) of the tumors. In nine of these, expression was
detected in >50% of the cells (Figure 1)
. By differential PCR, 19% (5 of 26)
of the ADCC tumors contained an amplified MDM2 gene as detected by a
ratio of >2.5 between the intensities of the MDM2 band and of the DRD2
gene used as control. In addition, two further ADCC showed an MDM2/DRD2
signal ratio between 2 and 2.5 (data not shown). In ADCE, mdm2 protein
was detectable by immunohistochemistry in 40% (10 of 25) of the
tumors, six of them showing positive staining in >50% of the tumor
cells. By differential PCR, only one ADCE showed an MDM2/DRD2 signal
ratio of >2.5 (4%), and one other tumor showed a ratio of between 2
and 2.5. All ADCC and ADCE with amplified MDM2 had wild-type TP53
sequences.
|
Precancerous and cancer lesions usually retain patterns of CK expression that characterize the cells and tissues from which they originate.2 Table 4 shows the pattern of expression of CKs 4, 7, and 13 in ADCC and ADCE. CK4 was expressed in most ADCE (83.5%) and in all ADCC tested. However, the two tumor types differed in the pattern of expression of CK7 and CK13, with >50% of ADCC being negative for both markers, and >80% of ADCE being positive for the same markers. These observations further substantiate the hypothesis that ADCC and ADCE originate from distinct cell types.
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
First, the patient profiles were different in the two tumor types. Although the characteristics of our ADCE patients (mean age, sex ratio) were similar to those reported by others,15-17 our group of ADCC patients included a higher proportion of female patients (35%, versus only 3.5% in ADCE; P < 0.002). The mean age was not significantly different between two groups. The proportion of regular smokers was lower among ADCC patients (47%, compared to 72% for ADCE). However, one of the most striking differences was the clinical history of associated tumors in patients with ADCC. Three of the nine female patients had a history of breast adenocarcinoma, occurring either before (in two cases) or after (in one case) the diagnosis of ADCC. To our knowledge, an association between ADCC and breast cancer has not been previously reported. ADCC has also not been reported in the spectrum of tumors occurring in individuals with germline mutations known to predispose to breast cancer, such as BRCA-1 or -2 carriers, or in the Li-Fraumeni syndrome. Two other individuals with ADCC developed another tumor (one adenocarcinoma of the intestine and one pleomorphic adenoma of the parotid). In contrast, in ADCE, only one patient had a history of associated squamous cell carcinoma of the head and neck, associated with a background of heavy tobacco and alcohol consumption.
Second, the tumors in the two groups showed differences in several molecular markers, including TP53 mutation, MDM2 amplification, and patterns of cytokeratin expression. The prevalence of TP53 mutations was 50% in ADCE, compared with 31% in ADCC (P = 0.09). For ADCE, our data are in agreement with the prevalence reported in the literature (117 mutations described in 205 tumors examined; 57%). However, for ADCC, our results diverge from those reported by Gleeson et al16 (63%) and, to a lesser extent, those of Fléjou et al15 (42%). We believe that these differences are the consequence of using different criteria to distinguish between ADCC and ADCE. The importance of the tumor definition is illustrated in a recent study by Ireland et al,25 who used the classification of Siewert and Stein.19 These authors noted that intestinal metaplasia was detectable in 89% of tumors of the esophagus, 58% of tumors of the cardia, and 33% of tumors of the subcardia. The TP53 mutation prevalence was 53%, 58%, and 17%, in the three subgroups, respectively. It is interesting to note that, in addition to the low prevalence of TP53 mutations, the subcardia group of Ireland et al25 resembles our ADCC group in several clinical features, including the sex ratio of the patients and the stage of the tumors.
The relatively low prevalence of TP53 mutations in ADCC prompted us to investigate the MDM2 status. We found that MDM2 was amplified in 19% of the ADCC analyzed (compared with only 4% in ADCE, P = 0.08). All tumors with amplified MDM2 had wild-type TP53 sequences. The rate of MDM2 amplification observed in ADCC is one of the highest ever reported in human carcinomas.26 These data suggest that amplification and overexpression of MDM2 may represent an alternative mechanism for p53 protein inactivation in ADCC. Although these results are of borderline statistical significance, our results suggest that ADCC and ADCE differ at the molecular level in the prevalence of both TP53 mutations and MDM2 amplification.
Finally, we found that the two types of cancer differed in their profile of expression of CK7 and CK13. CK7 and CK13 were frequently expressed in the ADCE (100% and 85%, respectively). In contrast, less than half of the ADCC samples expressed CK7 and CK13 (41% and 37%, respectively). These differences are consistent with the results of Goldblum,4 who reported that CK7 was constantly expressed in Barrett’s mucosa with intestinal metaplasia, but was never expressed in cardia mucosa with intestinal metaplasia. However, close examination of the upper part of the fundic mucosa revealed the presence of focal CK7 expression at the neck of the glands in a small series of normal gastric mucosa samples (data not shown; P Tanière, G Borghi-Scoazec, JF Mosnier, F Berger, P Hainaut, JY Scoazec, manuscript in preparation). This observation suggests that our detection of a subset of CK7-positive ADCC reflects a possible origin from such glandular structure rather than misclassification. In addition, our data indicate that CK4 and CK13 are not specific markers of a squamous origin of the tumor, because we detected their expression in ADCC, ADCE (Table 4),as well as in adenocarcinoma of the antrum (33% and 89% for, respectively, CK13 and CK4; data not shown).
In conclusion, our results show that ADCC differs from ADCE in the prevalence of TP53 mutations and the frequency of MDM2 amplification, and in the pattern of CK expression. Our results thus strongly support the hypothesis that ADCC and ADCE are two distinct pathological entities. This conclusion is at variance with previous reports by Gleeson et al16 and Fléjou et al,15 who found no major difference between the clinical, epidemiological, and molecular characteristics of these two cancers. The main reason for this discrepancy probably lies in the definition of the lesion. In the present study, the definition of ADCC was based on both localization (within 2 cm of the esophagogastric junction) and on the absence of residual Barrett’s metaplasia at the microscopic level. The presence of residual Barrett’s mucosa with a characteristic profile of CK expression seems to be an essential parameter for distinguishing ADCC from ADCE. Larger studies using precise selection criteria to distinguish between these tumors are necessary to further clarify the differences between the individual and clinical characteristics of the patients, as well as to identify the risk factors specifically associated with each tumor type.
|
Acknowledgements |
|---|
|
Footnotes |
|---|
Accepted for publication September 14, 2000.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
This article has been cited by other articles:
 |
|
 |
|
  S.-H. Kim, H. Nakagawa, A. Navaraj, Y. Naomoto, A. J.P. Klein-Szanto, A. K. Rustgi, and W. S. El-Deiry Tumorigenic Conversion of Primary Human Esophageal Epithelial Cells Using Oncogene Combinations in the Absence of Exogenous Ras Cancer Res., November 1, 2006; 66(21): 10415 - 10424. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. Kamangar, S. M. Dawsey, M. J. Blaser, G. I. Perez-Perez, P. Pietinen, C. J. Newschaffer, C. C. Abnet, D. Albanes, J. Virtamo, and P. R. Taylor Opposing Risks of Gastric Cardia and Noncardia Gastric Adenocarcinomas Associated With Helicobacter pylori Seropositivity. J Natl Cancer Inst, October 18, 2006; 98(20): 1445 - 1452. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. F. Souza and S. J. Spechler Concepts in the Prevention of Adenocarcinoma of the Distal Esophagus and Proximal Stomach CA Cancer J Clin, November 1, 2005; 55(6): 334 - 351. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. Le Calvez, A. Mukeria, J. D. Hunt, O. Kelm, R. J. Hung, P. Taniere, P. Brennan, P. Boffetta, D. G. Zaridze, and P. Hainaut TP53 and KRAS Mutation Load and Types in Lung Cancers in Relation to Tobacco Smoke: Distinct Patterns in Never, Former, and Current Smokers Cancer Res., June 15, 2005; 65(12): 5076 - 5083. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C J Buskens, A Sivula, B P van Rees, C Haglund, G J A Offerhaus, J J B van Lanschot, and A Ristimaki Comparison of cyclooxygenase 2 expression in adenocarcinomas of the gastric cardia and distal oesophagus Gut, December 1, 2003; 52(12): 1678 - 1683. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. T. Miller, S. Aggarwal, T. K. Lin, S. L. Dagenais, J. I. Contreras, M. B. Orringer, T. W. Glover, D. G. Beer, and L. Lin Amplification and Overexpression of the Dual-Specificity Tyrosine-(Y)-Phosphorylation Regulated Kinase 2 (DYRK2) Gene in Esophageal and Lung Adenocarcinomas Cancer Res., July 15, 2003; 63(14): 4136 - 4143. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. G. Casson, S. C. Evans, A. Gillis, G. A. Porter, P. Veugelers, S. J. Darnton, D. L. Guernsey, and P. Hainaut Clinical implications of p53 tumor suppressor gene mutation and protein expression in esophageal adenocarcinomas: Results of a ten-year prospective study J. Thorac. Cardiovasc. Surg., May 1, 2003; 125(5): 1121 - 1131. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. T. Y. Chung, Y. Yamada, R. Pannell, A. Forster, and T. H. Rabbitts The hepatitis C virus internal ribosome entry site facilitates efficient protein synthesis in blood vessel endothelium during tumour angiogenesis Nucleic Acids Res., April 15, 2003; 31(8): e46 - e46. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. van Dekken, J. C. Alers, P. H. J. Riegman, C. Rosenberg, H. W. Tilanus, and K. Vissers Molecular Cytogenetic Evaluation of Gastric Cardia Adenocarcinoma and Precursor Lesions Am. J. Pathol., June 1, 2001; 158(6): 1961 - 1967. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
