Molecular insights into gastrointestinal neuroendocrine tumours: importance and recent advances

Prognostic role of hERG1 Potassium Channels in Neuroendocrine Tumours of the Ileum and Pancreas

hERG1 potassium channels are widely expressed in human cancers of different origins, where they affect several key aspects of cellular behaviour. The present study was designed to evaluate the expression and clinical relevance of hERG1 protein in cancer tissues from patients suffering from neuroendocrine tumours (NETs) of ileal (iNETs) and pancreatic (pNETs) origin, with available clinicopathological history and follow-up. The study was carried out by immunohistochemistry with an anti-hERG1 monoclonal antibody. In a subset of samples, a different antibody directed against the hERG1/β1 integrin complex was also used. The analysis showed for the first time that hERG1 is expressed in human NETs originating from either the ileum or the pancreas. hERG1 turned out to have a prognostic value in NETs, showing (i) a statistically significant positive impact on OS of patients affected by ileal NETs, regardless the TNM stage; (ii) a statistically significant positive impact on OS of patients affected by aggressive (TNM stage IV) disease, either ileal or pancreatic; (iii) a trend to a negative impact on OS of patients affected by less aggressive (TNM stage I-III) disease, either ileal or pancreatic. Moreover, in order to evaluate whether ERG1 was functionally expressed in a cellular model of pNET, the INS1E rat insulinoma cell line was used, and it emerged that blocking ERG1 with a specific inhibitor of the channel (E4031) turned out in a significant reduction in cell proliferation.

Differential expression of cell-cycle regulators in human beta-cells derived from insulinoma tissue

INTRODUCTION

The low frequency of beta-cell replication in the adult human pancreas limits beta-cell regeneration. A better understanding of the regulation of human beta-cell proliferation is crucial to develop therapeutic strategies aiming to enhance beta-cell mass.

METHODS

To identify factors that control beta-cell proliferation, cell-cycle regulation was examined in human insulinomas as a model of increased beta-cell proliferation (n=11) and healthy pancreatic tissue from patients with benign pancreatic tumors (n=9). Tissue sections were co-stained for insulin and cell-cycle proteins. Transcript levels of selected cell-cycle factors in beta-cells were determined by qRT-PCR after performing laser-capture microdissection.

RESULTS

The frequency of beta-cell replication was 3.74±0.92% in the insulinomas and 0.11±0.04% in controls (p=0.0016). p21 expression was higher in insulinomas (p=0.0058), and Rb expression was higher by trend (p=0.085), whereas p16 (p<0.0001), Cyclin C (p<0.0001), and p57 (p=0.018) expression levels were lower. The abundance of Cyclin D3 (p=0.62) and p27 (p=0.68) was not different between the groups. The reduced expression of p16 (p<0.0001) and p57 (p=0.012) in insulinomas and the unchanged expression of Cyclin D3 (p=0.77) and p27 (p=0.55) were confirmed using qRT-PCR.

CONCLUSIONS

The expression of certain cell-cycle factors in beta-cells derived from insulinomas and healthy adults differs markedly. Targeting such differentially regulated cell-cycle proteins may evolve as a future strategy to enhance beta-cell regeneration.

Pancreatic endocrine tumors

Pancreatic endocrine tumors have been steadily growing in incidence and prevalence during the last two decades, showing an incidence of 4-5/1,000,000 population. They represent a heterogeneous group with very varying tumor biology and prognosis. About half of the patients present clinical symptoms and syndromes related to substances released from the tumors (Zollinger-Ellison syndrome, insulinoma, glucagonoma, etc) and the other half are so-called nonfunctioning tumors mainly presenting with symptoms such as obstruction, jaundice, bleeding, and abdominal mass. Ten percent to 15% of the pancreatic endocrine tumors are part of an inherited syndrome such as multiple endocrine neoplasia type 1 (MEN-1), von Hippel-Lindau (VHL), neurofibromatosis, or tuberousclerosis. The diagnosis is based on histopathology demonstrating neuroendocrine features such as positive staining for chromogranin A and specific hormones such as gastrin, proinsulin, and glucagon. Moreover, the biochemical diagnosis includes measurement of chromogranins A and B or specific hormones such as gastrin, insulin, glucagon, and vasoactive intestinal polypeptide (VIP) in the circulation. In addition to standard localization procedures, radiology (computed tomography [CT] scan, magnetic resonance imaging [MRI], ultrasound [US]), somatostatin receptor scintigraphy, and most recently positron emission tomography with specific isotopes such as (11)C-5 hydroxytryptamin ((11)C-5-HTP), fluorodopa and (68)Ga-1,4,7,10-tetra-azacyclododecane-N,N',N″,N‴-tetra-acetic acid (DOTA)-octreotate are performed. Surgery is still one of the cornerstones in the management of pancreatic endocrine tumors, but curative surgery is rarely obtained in most cases because of metastatic disease. Debulking and other cytoreductive procedures might facilitate systemic treatment. Cytotoxic drugs, biological agents, such as somatostatin analogs, alpha interferons, mammalian target of rapamycin (mTOR) inhibitors and tyrosine kinase inhibitors are routinely used. Tumor-targeted radioactive treatment is available in many centres in Europe and is effective in patients with tumors that express high content of somatostatin receptors type 2 and 5. In the future, treatment will be based on tumor biology and molecular genetics with the aim of so-called personalized medicine.

Clinical implications of microsatellite instability and MLH1 gene inactivation in sporadic insulinomas

CONTEXT

The molecular pathogenesis of sporadic insulinomas is unknown. There is a lack of biomarker to distinguish benign and malignant form of insulinoma.

OBJECTIVE

Our objective was to confirm the occurrence of microsatellite instability (MSI) in insulinomas, to identify alterations of mismatch repair (MMR) genes in the tumors, and to evaluate the possibility to distinguish benign and malignant insulinoma or to predict the clinical outcome of patients with these alterations.

DESIGN AND PATIENTS

We detected MSI and inactivation of MLH1 gene in 55 sporadic insulinomas by PCR, immunohistochemical staining, allelic typing, analysis of promoter methylation, and exon mutations. Their correlations with clinicopathological characteristics were analyzed with univariate and multivariate statistic analysis.

RESULTS

A high rate of MSI (MSI-H) was found in 33% of sporadic insulinomas. Reduced expression of mutL homolog 1 (MLH1) protein was observed in 36% of insulinomas and correlated with MSI-H (P = 0.008). Promoter methylation and loss of heterozygosity of MLH1 gene was found in 31 and 49% of insulinomas, respectively. Reduced expression of MLH1 and MSI-H were significantly associated with both tumor malignancy (P = 0.033 and P = 4.8 x 10(-6), respectively) and incurable disease (P = 0.006 and P = 0.001, respectively).

CONCLUSION

High frequency of MSI occurred in sporadic insulinomas. The silencing of MLH1 gene may partially contribute to the MSI-H in the tumors. Assessing MSI-H and expressions of MLH1 could be used to distinguish benign and malignant insulinomas and to predict the outcome of patients.

Inherited pancreatic endocrine tumor syndromes: advances in molecular pathogenesis, diagnosis, management, and controversies

Pancreatic endocrine tumors (PETs) can occur as part of 4 inherited disorders, including Multiple Endocrine Neoplasia type 1 (MEN1), von Hippel-Lindau disease (VHL), neurofibromatosis 1 (NF-1) (von Recklinghausen disease), and the tuberous sclerosis complex (TSC). The relative frequency with which patients who have these disorders develop PETs is MEN1>VHL>NF-1>TSC. Over the last few years, there have been major advances in the understanding of the genetics and molecular pathogenesis of these disorders as well in the localization and the medical and surgical treatment of PETs in such patients. The study of PETs in these disorders not only has provided insights into the possible pathogenesis of sporadic PETs but also has presented several unique management and treatment issues, some of which are applicable to patients with sporadic PETs. Therefore, the study of PETs in these uncommon disorders has provided valuable insights that, in many cases, are applicable to the general group of patients with sporadic PETs. In this article, these areas are reviewed briefly along with the current state of knowledge of the PETs in these disorders, and the controversies that exist in their management are summarized briefly and discussed.

Gastrointestinal neuroendocrine tumors: pancreatic endocrine tumors

Pancreatic endocrine tumors (PETs) have long fascinated clinicians and investigators despite their relative rarity. Their clinical presentation varies depending on whether the tumor is functional or not, and also according to the specific hormonal syndrome produced. Tumors may be sporadic or inherited, but little is known about their molecular pathology, especially the sporadic forms. Chromogranin A appears to be the most useful serum marker for diagnosis, staging, and monitoring. Initially, therapy should be directed at the hormonal syndrome because this has the major initial impact on the patient's health. Most PETs are relatively indolent but ultimately malignant, except for insulinomas, which predominantly are benign. Surgery is the only modality that offers the possibility of cure, although it generally is noncurative in patients with Zollinger-Ellison syndrome or nonfunctional PETs with multiple endocrine neoplasia-type 1. Preoperative staging of disease extent is necessary to determine the likelihood of complete resection although debulking surgery often is believed to be useful in patients with unresectable tumors. Once metastatic, biotherapy is usually the first modality used because it generally is well tolerated. Systemic or regional therapies generally are reserved until symptoms occur or tumor growth is rapid. Recently, a number of newer agents, as well as receptor-directed radiotherapy, are being evaluated for patients with advanced disease. This review addresses a number of recent advances regarding the molecular pathology, diagnosis, localization, and management of PETs including discussion of peptide-receptor radionuclide therapy and other novel antitumor approaches. We conclude with a discussion of future directions and unsettled problems in the field.

Treatment of gastrointestinal neuroendocrine tumors with inhibitors of growth factor receptors and their signaling pathways: recent advances and future perspectives

The limited efficacy of conventional cytotoxic treatment regimes for advanced gastrointestinal neuroendocrine cancers emphasizes the need for novel and more effective medical treatment options. Recent findings on the specific biological features of this family of neoplasms has led to the development of new targeted therapies, which take into account the high vascularization and abundant expression of specific growth factors and cognate tyrosine kinase receptors. This review will briefly summarize the status and future perspectives of antiangiogenic, mTOR- or growth factor receptor-based pharmacological approaches for the innovative treatment of gastrointestinal neuroendocrine tumors. In view of the multitude of novel targeted approaches, the rationale for innovative combination therapies, i.e. combining growth factor (receptor)-targeting agents with chemo- or biotherapeutics or with other novel anticancer drugs such as HDAC or proteasome inhibitors will be taken into account.

Prognostic factors at diagnosis and value of WHO classification in a mono-institutional series of 180 non-functioning pancreatic endocrine tumours

BACKGROUND

Non-functioning pancreatic endocrine tumours (NF-PETs) are an aggressive gastroenteropancreatic neoplasm. The present study assessed survival, value of World Health Organisation (WHO) classification and prognostic utility of clinicopathological parameters at diagnosis.

PATIENTS AND METHODS

From 1990 to 2004, 180 patients with NF-PETs were entered in a prospective database, and predictors of prognosis were tested in uni- and multivariate models.

RESULTS

There were 25 (14%) benign lesions, 38 (21%) neoplasms of uncertain behaviour, 100 well-differentiated carcinomas (56%) and 17 poorly differentiated carcinomas (9%). Radical resection was possible in 93 cases (51.6%). Overall 5-, 10- and 15-year survival rates were 67%, 49.3% and 32.8%, respectively, and were significantly higher in radically resected patients (93%, 80.8% and 65.2%, respectively; P < 0.00001). By multivariate analysis, poor differentiation [hazard ratio (HR) 7.3; P = 0.0001], nodal metastases (HR 3.05; P = 0.02), liver metastases (HR 3.29; P = 0.003), K(i)-67 >5% (HR 2.5; P = 0.012) and weight loss (HR 3.06; P = 0.001) were significantly associated with mortality.

CONCLUSION

This study confirms the good long-term survival of patients with NF-PETs and the prognostic value of WHO classification, liver metastases, poor differentiation, Ki-67, nodal metastases and weight loss. These latter two parameters have a prognostic value similar to that of liver metastases and Ki-67.

Rap1/B-Raf signaling is activated in neuroendocrine tumors of the digestive tract and Raf kinase inhibition constitutes a putative therapeutic target

OBJECTIVE

Molecular pathogenesis of digestive neuroendocrine tumors (dNETs) is largely unknown. Recently, the serine-threonine kinase B-Raf was identified as an oncogene in endocrine cancer such as thyroid carcinoma. In endocrine cells, the small G-protein Rap1 stimulates mitogen-activated protein kinase (MAPK) signaling by activating B-Raf. We examined the expression of Rap1 and B-Raf in dNETs and their contribution to MAPK signaling in neuroendocrine cell lines. In addition, we explored the effect of suppressing B-Raf kinase by the recently developed inhibitor BAY43-9006 (Sorafinib) on growth, apoptosis and MAPK activation neuroendocrine cell lines.

METHODS AND RESULTS

Expression of Rap1 and B-Raf in dNETs (19 insulinomas, 15 carcinoid tumors and 10 gastrinomas) was examined by immunohistochemistry, which revealed that Rap1 and B-Raf were highly prevalent in the majority of dNETs. Overexpression of Rap1 and B-Raf activated MAPK extracellular dependent kinase (ERK) ERK-2 and ERK-dependent transcription factor Elk-1 in neuroendocrine cell lines Bon and INS-1. Suppression of B-Raf by BAY43-9006 inhibited growth and induced apoptosis in Bon and INS-1 cells. In addition, BAY43-9006 suppressed phosphorylation of MAPK ERK1/2 and its upstream kinase MEK1/2 in Bon and INS-1 cells.

CONCLUSION

These results indicate that Rap1-B-Raf signaling may contribute to pathogenesis of dNETs and provides a molecular target for treatment of dNETs.

Increased islet beta cell replication adjacent to intrapancreatic gastrinomas in humans

AIMS/HYPOTHESIS

Type 1 and type 2 diabetes are characterised by a beta cell deficit. Islet hyperplasia has been described in patients with Zollinger-Ellison syndrome secondary to gastrin-producing tumours (gastrinomas), and gastrin therapy has increased beta cell mass in rodents and human islets in vitro. In the present studies we addressed the following questions: (1) In pancreas specimens from gastrinoma cases, is the fractional beta cell area increased? (2) If so, is this restricted to tumour-adjacent islets or also present in tumour-distant islets? (3) Is new beta cell formation (beta cell replication and islet neogenesis) increased and beta cell apoptosis decreased in pancreas specimens from gastrinoma cases?

METHODS

Pancreas was obtained at surgery from four patients with Zollinger-Ellison syndrome caused by pancreatic gastrinomas and 15 control subjects at autopsy.

RESULTS

Islet fractional beta cell area (p<0.001), islet size (p<0.001) and beta cell replication (Ki67 staining) (p<0.05) were increased in islets adjacent to the tumours, but not in tumour-distant pancreas, compared with control subjects. We did not observe any differences in beta cell apoptosis or in the number of insulin-positive cells in ducts either adjacent to or distant from the tumour.

CONCLUSIONS/INTERPRETATION

One or more factors released by human gastrinomas increase beta cell replication in islets immediately adjacent to the tumour, but not in tumour-distant islets. While these findings demonstrate that adult human beta cells can be driven into the cell cycle, they caution against the therapeutic usefulness of gastrin, since islets located >1 cm away from the gastrinomas did not exhibit changes in beta cell turnover, despite markedly elevated systemic gastrin levels sufficient to cause severe gastrointestinal symptoms.

Chromosome 1q loss of heterozygosity frequently occurs in sporadic insulinomas and is associated with tumor malignancy

The pathogenesis of sporadic insulinomas is not clear, and there are no reliable genetic determinants that are useful to distinguish malignant and benign forms of this tumor. It was reported that 1q LOH might contribute to pathogenesis in gastrinomas and was correlated with tumor progression. However, little data are available on 1q LOH in sporadic insulinomas. In our study, we determine whether 1q LOH occurs in sporadic insulinomas and is associated with tumor malignancy by performing 1q allelotyping with 17 markers in 40 tumors and pair normal DNA. Thirty-five (88%) insulinomas had 1q LOH. Of the 35 insulinomas with 1q LOH, 14 (40%) had 1q21.3-23.2 LOH over a 7.5 cM region (SRO-1), whereas LOH in 21 tumors (60%) occurred at 1q31.3 over an 11.4 cM area (SRO-2). Of 24 tumors without MEN1 LOH, 20 had either SRO-1 or SRO-2 LOH (83%), whereas in 16 tumors with MEN1 LOH, 9 were shown to have LOH at either SRO-1 or SRO-2 (56%) (p = 0.065). This result suggests that LOH at 2 SRO might be MEN1 gene independent and may contribute to the pathogenesis in a subset of insulinomas without MEN1 gene LOH. The presence of 1q21.3-23.2 LOH is significantly associated with malignancy of insulinomas (p = 0.014). The high frequency of LOH at 1q 21.3-23.2 and 1q31.3 suggests these 2 areas may harbor putative tumor suppressor genes that may play an important role in the tumorigenesis of a subset of insulinomas. LOH at 1q21.3-23.2, which was associated with tumor malignancy, could be one of the genetic markers for identifying malignancy in sporadic insulinomas.

Advances in evaluation and management of gastrinoma in patients with Zollinger-Ellison syndrome

Gastrinomas producing Zollinger-Ellison syndrome are the most frequent symptomatic, malignant pancreatic endocrine tumor syndrome. Recently, a number of important studies have examined their molecular pathogenesis and natural history and provided important guidelines for their treatment. Each of these areas is briefly reviewed in this article.

Increased expression of insulin-like growth factor I and/or its receptor in gastrinomas is associated with low curability, increased growth, and development of metastases

PURPOSE

Growth factors, particularly insulin-like growth factor I (IGF-I) and IGF-I receptor (IGF-IR) in some nonendocrine and a few endocrine tumors, are thought important in recurrence, growth, and aggressiveness. Whether this is true of neuroendocrine tumors such as gastrinomas is unclear. The aim of this study was to address this question in gastrinomas.

EXPERIMENTAL DESIGN

IGF-I and IGF-IR expression in gastrinomas from 54 patients with Zollinger-Ellison syndrome were analyzed and correlated with clinical/tumor characteristics. IGF-I and IGF-IR mRNA levels were determined by competitive reverse transcription-PCR. IGF-IR expression, assessed by immunohistochemistry, was done on a subset.

RESULTS

IGF-IR mRNA was found in 100% and IGF-I in 89%. IGF-I mRNA expression varied by >254-fold, IGF-IR by 2,670-fold, and the levels correlated in a given tumor. The IGF-IR level was lower in gastrinomas of patients who were rendered disease free and increased levels correlated with tumor growth, aggressiveness, extent, and with liver metastases. Increased IGF-I levels correlated with increased growth, tumor extent, and aggressiveness. Neither IGF-IR nor IGF-I levels correlated with tumor location, size, or its clinical/functional features. The IGF-IR correlated with disease-free survival. IGF-IRbeta was found in 31 of 32 tumors (97%) by immunohistochemistry.

CONCLUSIONS

These results indicate that IGF-I and IGF-IR are expressed in almost all gastrinomas. Furthermore, assessment of IGF-I/IGF-IR expression in gastrinomas may be clinically useful in identifying those patients with more aggressive tumors who might benefit from more aggressive treatment.

Hereditary hormone excess: genes, molecular pathways, and syndromes

Hereditary origin of a tumor helps toward early discovery of its mutated gene; for example, it supports the compilation of a DNA panel from index cases to identify that gene by finding mutations in it. The gene for a hereditary tumor may contribute also to common tumors. For some syndromes, such as hereditary paraganglioma, several genes can cause a similar syndrome. For other syndromes, such as multiple endocrine neoplasia 2, one gene supports variants of a syndrome. Onset usually begins earlier and in more locations with hereditary than sporadic tumors. Mono- or oligoclonal ("clonal") tumor usually implies a postnatal delay, albeit less delay than for sporadic tumor, to onset and potential for cancer. Hormone excess from a polyclonal tissue shows onset at birth and no benefit from subtotal ablation of the secreting organ. Genes can cause neoplasms through stepwise loss of function, gain of function, or combinations of these. Polyclonal hormonal excess reflects abnormal gene dosage or effect, such as activation or haploinsufficiency. Polyclonal hyperplasia can cause the main endpoint of clinical expression in some syndromes or can be a precursor to clonal progression in others. Gene discovery is usually the first step toward clarifying the molecule and pathway mutated in a syndrome. Most mutated pathways in hormone excess states are only partly understood. The bases for tissue specificity of hormone excess syndromes are usually uncertain. In a few syndromes, tissue selectivity arises from mutation in the open reading frame of a regulatory gene (CASR, TSHR) with selective expression driven by its promoter. Polyclonal excess of a hormone is usually from a defect in the sensor system for an extracellular ligand (e.g., calcium, glucose, TSH). The final connections of any of these polyclonal or clonal pathways to hormone secretion have not been identified. In many cases, monoclonal proliferation causes hormone excess, probably as a secondary consequence of accumulation of cells with coincidental hormone-secretory ability.

Zollinger-Ellison syndrome revisited: diagnosis, biologic markers, associated inherited disorders, and acid hypersecretion

Despite general awareness of Zollinger-Ellison syndrome (ZES) by most physicians and more than 3000 articles written about it since 1955, the diagnosis of ZES is still delayed for a mean of 5 years. Recent studies show it is being delayed even more with the widespread use of proton pump inhibitors. A number of tumor markers, in addition to assessing serum gastrin, such as chromogranin A, neuron-specific enolase, and subunits of chorionic gonadotropin, have been proposed for use in either the diagnosis of pancreatic endocrine tumors, such as gastrinomas, or for assessment of tumor extent and growth. In this article important recent insights into the diagnosis of ZES as well as the clinical usefulness of assessing tumor markers for diagnosis and determination of disease extent and growth are discussed. Approximately 25% of ZES cases are due to multiple endocrine neoplasia type 1 (MEN1). A number of important studies in this group of patients are also reviewed. Finally, almost every patient with ZES has marked gastric acid hypersecretion, and its current treatment as well as the long-term possible side effects are reviewed briefly.

Resolved and unresolved controversies in the surgical management of patients with Zollinger-Ellison syndrome

OBJECTIVE

Highlight unresolved controversies in the management of Zollinger-Ellison syndrome (ZES).

SUMMARY BACKGROUND DATA

Recent studies have resolved some of the previous controversies including the surgical cure rate in patients with and without Multiple Endocrine Neoplasia-type1 (MEN1), the biological behavior of duodenal and pancreatic gastrinomas, role of imaging studies to localize tumor, and gastrectomy to manage acid output.

METHODS

Review of the literature based on computer searches in Index Medicus, Pubmed and Ovid.

RESULTS

Current controversies as identified in the literature include the role of endoscopic ultrasound (EUS), surgery in ZES patients with MEN1, pancreaticoduodenectomy (Whipple procedure), lymph node primary gastrinoma, parietal cell vagotomy, reoperation and surgery for metastatic tumor, and the use of minimally invasive surgical techniques to localize and remove gastrinoma.

CONCLUSIONS

It is hoped that future studies will focus on these issues to improve the surgical management of ZES patients.

X-chromosome loss of heterozygosity frequently occurs in gastrinomas and is correlated with aggressive tumor growth

BACKGROUND

Recent studies have shown that tumor growth, rather than hormone overproduction, is the leading cause of death among patients with gastrinomas and other malignant gastrointestinal endocrine tumors. No patient/laboratory characteristics accurately predict which tumors will exhibit aggressive growth. Furthermore, little is known regarding the molecular pathogenesis of these tumors. X-chromosome loss of heterozygosity (LOH) occurs in some nonendocrine tumors, and its presence can be associated with aggressive growth/decreased survival. Data on X-chromosome LOH in gastrointestinal endocrine tumors are conflicting. Therefore, the purpose of the current study was to determine whether X-chromosome LOH occurred in gastrinomas and, if so, whether it was correlated with tumor growth, tumor behavior, and/or prognosis.

METHODS

X chromosome allelotyping was performed using 12 microsatellite markers spaced throughout the chromosome using DNA from leukocytes and microdissected gastrinoma specimens from 16 female patients. The presence of X-chromosome LOH was analyzed for correlations with clinical and laboratory tumor characteristics as well as tumor growth characteristics.

RESULTS

Nine gastrinoma specimens (56%) had X-chromosome LOH, ranging from 6% to 23% at the 12 different loci studied. X-chromosome LOH was significantly associated with aggressive postoperative tumor growth, increased primary tumor size, and pancreatic primaries. In 6 tumor specimens, LOH occurred on Xp22.1-22.3 over a 28.4-centimorgan region.

CONCLUSIONS

X-chromosome LOH was common in gastrinoma specimens from female patients, and its presence was found to be a potentially useful molecular/genetic prognostic factor for aggressive growth.

Gastrinomas: advances in diagnosis and management

Gastrinomas causing Zollinger-Ellison syndrome (ZES) are the most common functional, malignant pancreatic endocrine tumors. In this paper, the diagnosis and treatment of these tumors are reviewed, incorporating recent advances in each area. Furthermore, recent advances in their pathology, molecular pathogenesis, and aspects of their localization using somatostatin receptor scintigraphy, as well as their treatment are discussed. Recent data from our NIH prospective studies on patients with ZES are included to illustrate many of these points.

Co-existence of hyperparathyroidism, hypergastrinaemia and multiple gastric carcinoids is not always due to incomplete expression of the MEN-1 syndrome

Until recently, the association of primary hyperparathyroidism and gastric carcinoid, with or without hypergastrinaemia, had been considered an incomplete form of multiple endocrine neoplasia type 1. This is because it seemed unlikely that the rare joint appearance of these diseases could occur only by chance. It is now possible to evaluate the pathogenetic involvement of the multiple endocrine neoplasia type 1 gene in many, apparently sporadic, clinical conditions. This is a case report of a female mimicking multiple endocrine neoplasia type 1 due to the presence of hyperparathyroidism, gastric carcinoid, and hypergastrinaemia. However, involvement of the MEN-1 gene (exons 2-10) was not detected, whereas hypergastrinaemia was attributed to a chronic atrophic gastritis.

Current surgical management of Zollinger-Ellison syndrome (ZES) in patients without multiple endocrine neoplasia-type 1 (MEN1)

The role of surgery in the management of patients with sporadic (not part of multiple endocrine neoplasia type 1) Zollinger-Ellison syndrome (ZES) is controversial. In this setting, 60-90% of gastrinomas are malignant and medical therapy can control the gastric acid hypersecretion in virtually every patient. Therefore, the progression of tumor is the major determinant of survival. Surgery will cure approximately one-third of patients with sporadic ZES. It will decrease the development of liver metastases and may improve survival. Somatostatin receptor scintigraphy is the best preoperative localization study. Its results are as good as all other imaging studies combined. Operative techniques should always include duodenotomy (opening the duodenum) and meticulous dissection of lymph nodes in the gastrinoma triangle, because duodenal primary tumors are often missed and lymph node primary tumors or metastases are common. Postoperative evaluation should include secretin test because it is the most sensitive method to document cure and detect tumor recurrence.