Pathomorphologic, biochemical, and diagnostic aspects of gastrinomas (Zollinger-Ellison syndrome)

Diffuse, Adult-Onset Nesidioblastosis/Non-Insulinoma Pancreatogenous Hypoglycemia Syndrome (NIPHS): Review of the Literature of a Rare Cause of Hyperinsulinemic Hypoglycemia

Differential diagnosis of hypoglycemia in the non-diabetic adult patient is complex and comprises various diseases, including endogenous hyperinsulinism caused by functional β-cell disorders. The latter is also designated as nesidioblastosis or non-insulinoma pancreatogenous hypoglycemia syndrome (NIPHS). Clinically, this rare disease presents with unspecific adrenergic and neuroglycopenic symptoms and is, therefore, often overlooked. A combination of careful clinical assessment, oral glucose tolerance testing, 72 h fasting, sectional and functional imaging, and invasive insulin measurements can lead to the correct diagnosis. Due to a lack of a pathophysiological understanding of the condition, conservative treatment options are limited and mostly ineffective. Therefore, nearly all patients currently undergo surgical resection of parts or the entire pancreas. Consequently, apart from faster diagnosis, more elaborate and less invasive treatment options are needed to relieve the patients from the dangerous and devastating symptoms. Based on a case of a 23-year-old man presenting with this disease in our department, we performed an extensive review of the medical literature dealing with this condition and herein presented a comprehensive discussion of this interesting disease, including all aspects from epidemiology to therapy.

Successful Lifetime/Long-Term Medical Treatment of Acid Hypersecretion in Zollinger-Ellison Syndrome (ZES): Myth or Fact? Insights from an Analysis of Results of NIH Long-Term Prospective Studies of ZES

Analysis of the efficacy/pharmacology of long-term/lifetime medical treatment of acid hypersecretion in a large cohort of ZES patients in a prospective study. This study includes the results from all 303 patients with established ZES who were prospectively followed and received acid antisecretory treatment with either H2Rs or PPIs, with antisecretory doses individually titrated by the results of regular gastric acid testing. The study includes patients treated for short-term periods (<5 yrs), patients treated long-term (>5 yrs), and patients with lifetime treatment (30%) followed for up to 48 years (mean 14 yrs). Long-term/lifelong acid antisecretory treatment with H2Rs/PPIs can be successfully carried out in all patients with both uncomplicated and complicated ZES (i.e., with MEN1/ZES, previous Billroth 2, severe GERD). This is only possible if drug doses are individually set by assessing acid secretory control to establish proven criteria, with regular reassessments and readjustments. Frequent dose changes both upward and downward are needed, as well as regulation of the dosing frequency, and there is a primary reliance on the use of PPIs. Prognostic factors predicting patients with PPI dose changes are identified, which need to be studied prospectively to develop a useful predictive algorithm that could be clinically useful for tailored long-term/lifetime therapy in these patients.

Impact of proton pump inhibitor treatment on pancreatic beta-cell area and beta-cell proliferation in humans

INTRODUCTION

Gastrin has been shown to promote beta-cell proliferation in rodents, but its effects in adult humans are largely unclear. Proton pump inhibitors (PPIs) lead to endogenous hypergastrinaemia, and improved glucose control during PPI therapy has been reported in patients with diabetes. Therefore, we addressed whether PPI treatment is associated with improved glucose homoeostasis, islet cell hyperplasia or increased new beta-cell formation in humans.

PATIENTS AND METHODS

Pancreatic tissue specimens from 60 patients with and 33 patients without previous PPI therapy were examined. The group was subdivided into patients without diabetes (n = 27), pre-diabetic patients (n = 31) and patients with diabetes (n = 35).

RESULTS

Fasting glucose and HbA1c levels were not different between patients with and without PPI therapy (P = 0.34 and P = 0.30 respectively). Beta-cell area was higher in patients without diabetes than in patients with pre-diabetes or diabetes (1.33 ± 0.12%, 1.05 ± 0.09% and 0.66 ± 0.07% respectively; P < 0.0001). There was no difference in beta-cell area between patients with and without PPI treatment (1.05 ± 0.08% vs 0.87 ± 0.08%, respectively; P = 0.16). Beta-cell replication was rare and not different between patients with and without PPI therapy (P = 0.20). PPI treatment was not associated with increased duct-cell replication (P = 0.18), insulin expression in ducts (P = 0.28) or beta-cell size (P = 0.63).

CONCLUSIONS

These results suggest that in adult humans, chronic PPI treatment does not enhance beta-cell mass or beta-cell function to a relevant extent.

Zollinger-Ellison syndrome: Revelation of the gastrinoma triangle

Zollinger-Ellison syndrome is a complex condition in which one or more tumors form in the patient's pancreas or upper duodenum. These tumors, called gastrinomas, secrete excessive amounts of gastrin, and almost all develop ulcers. The vast majority of gastrinomas are present within the “gastrinoma triangle,” which is composed of the porta hepatis, duodenal sweep, and pancreatic head. As surgery remains the treatment of choice, localization of the primary lesion is often challenging but essential. We present a 50-year-old man with a tentative diagnosis of Zollinger-Ellison syndrome. His In-111 pentetreotide scan, fused onto a Tc-99m abdomen image, revealed an avid lesion adjacent to the duodenal loop. Operative resection was performed, and a primary pancreatic gastrinoma was diagnosed by immunohistochemical staining. The neuroendocrine tumors have somatostatin receptors upon them. Therefore, a penteteotide scan, using In-111 radiolabelled somatostatin analogues, is the current technique of choice. This dual-isotope display permits a visual perception of anatomic landmarks around the lesion.

Gastrin treatment stimulates β-cell regeneration and improves glucose tolerance in 95% pancreatectomized rats

β-Cell mass reduction is a central aspect in the development of type 1 and type 2 diabetes, and substitution or regeneration of the lost β-cells is a potentially curative treatment of diabetes. To study the effects of gastrin on β-cell mass in rats with 95% pancreatectomy (95%-Px), a model of pancreatic regeneration, rats underwent 95% Px or sham Px and were treated with [15 leu] gastrin-17 (Px+G and S+G) or vehicle (Px+V and S+V) for 15 d. In 95% Px rats, gastrin treatment reduced hyperglycemia (280 ± 52 mg vs. 436 ± 51 mg/dl, P < 0.05), and increased β-cell mass (1.15 ± 0.15 mg)) compared with vehicle-treated rats (0.67 ± 0.15 mg, P < 0.05). Gastrin treatment induced β-cell regeneration by enhancing β-cell neogenesis (increased number of extraislet β-cells in Px+G: 0.42 ± 0.05 cells/mm(2) vs. Px+V: 0.27 ± 0.07 cells/mm(2), P < 0.05, and pancreatic and duodenal homeobox 1 expression in ductal cells of Px+G: 1.21 ± 0.38% vs. Px+V: 0.23 ± 0.10%, P < 0.05) and replication (Px+G: 1.65 ± 0.26% vs. S+V: 0.64 ± 0.14%; P < 0.05). In addition, reduced β-cell apoptosis contributed to the increased β-cell mass in gastrin-treated rats (Px+G: 0.07 ± 0.02%, Px+V: 0.23 ± 0.05%; P < 0.05). Gastrin action on β-cell regeneration and survival increased β-cell mass and improved glucose tolerance in 95% Px rats, supporting a potential role of gastrin in the treatment of diabetes.

The Zollinger-Ellison syndrome and mismeasurement of gastrin

BACKGROUND & AIMS

Zollinger-Ellison syndrome (ZES) is characterized by hypersecretion of gastric acid, severe peptic ulcerations in the upper small intestine, and diarrhea. It is usually diagnosed by measuring increased levels of gastrin in plasma.

METHODS

We examined the accuracy of commercial kits to measure gastrin (7 radioimmunoassays and 5 enzyme-linked immunosorbent assays), using plasma from 40 patients suspected or known to have ZES. Each sample was analyzed using the 12 kits and a reference assay that measures bioactive gastrin in plasma, irrespective of size and amino acid derivatization. Known concentrations of peptides with identical sequences to circulating gastrins were also assessed by all assays. Molecular patterns in plasma from patients with ZES were examined by chromatography and monitored by kits that measure false-low or false-high concentrations of gastrin.

RESULTS

Failure to diagnose gastrinomas has serious consequences. Four kits found false-low concentrations of gastrin in 20% to 80% of the patients. Specificity assessment showed that the antibodies used in these kits bound only gastrin-17. Three kits found false-high concentrations of gastrin, because the reagents had increased reactions to sulfated gastrins or to unspecific factors in plasma. Thus, only 5 of 12 kits tested accurately measure plasma concentrations of gastrin.

CONCLUSIONS

Seven of 12 tested commercial kits inaccurately measure plasma concentrations of gastrin; these assays used antibodies with inappropriate specificity that were insufficiently validated. Misdiagnosis of gastrinoma based on lack of specificity of assays for gastrin results in ineffective or inappropriate therapy for patients with ZES.

Giant gastrinoma in a child: case report and review

Gastrinomas are rare neuroendocrine tumours. A 9-year-old boy who initially presented with recurrent upper abdominal pain and was managed as hyperacidity syndrome was later diagnosed to have a primary, retroperitoneal, extra pancreatic gastrinoma after an asymptomatic period of 6 years is presented. At the second presentation, the contrast-enhanced CT revealed an epigastric mass and serum gastrin was grossly elevated. A complete excision of the mass was done; histopathological evaluation showed a well-differentiated neuroendocrine tumour. At a year follow up, the child is asymptomatic and the review imaging and serum gastrin levels are normal.

Growth-promoting actions of peptide hormones

In common with other growth-promoting hormones, peptide hormones evoke multiple biochemical responses in their target tissues. These can be divided into two groups: (a) rapid effects involving permeability properties of the target cell to amino acids, sugars and ions or changes in key intracellular metabolites like cyclic nucleotides; (b) slow responses based on the stimulation of RNA and protein synthesis. The impossibility of explaining all the late events as the results of early changes raises the possibility that more than one species of hormone receptor exists. It is proposed that the final expression of growth and maturation results from the cooperative interaction of rapid and slow responses of the target cell to the hormone.

Neuroendocrine tumors. Biotherapy

This review gives an introduction to the classification and staging of neuroendocrine tumors, as the prognostic implications of these classifications influence therapeutic decisions. The indications for biotherapy are given, together with a short update on the mechanism of somatostatin analogs and interferon-alpha therapy. This is followed by an in-depth description of the use of biotherapy, its results with respect to symptomatic and antiproliferative treatment, as well as its side-effects.

Serum gastrin in Zollinger-Ellison syndrome: II. Prospective study of gastrin provocative testing in 293 patients from the National Institutes of Health and comparison with 537 cases from the literature. evaluation of diagnostic criteria, proposal of new criteria, and correlations with clinical and tumoral features

In two-thirds of patients with Zollinger-Ellison syndrome (ZES), fasting serum gastrin (FSG) levels overlap with values seen in other conditions. In these patients, gastrin provocative tests are needed to establish the diagnosis of ZES. Whereas numerous gastrin provocative tests have been proposed, only the secretin, calcium, and meal tests are widely used today. Many studies have analyzed gastrin provocative test results in ZES, but they are limited by small patient numbers and methodologic differences. To address this issue, we report the results of a prospective National Institutes of Health (NIH) study of gastrin provocative tests in 293 patients with ZES and compare these data with those from 537 ZES and 462 non-ZES patients from the literature. In 97%-99% of gastrinoma patients, an increase in serum gastrin post secretin (Delta secretin) or post calcium (Delta calcium) occurred. In NIH ZES patients with <10-fold increase in FSG, the sensitivity/specificity of the widely used criteria were as follows: Delta secretin > or =200 pg/mL (83%/100%), Delta secretin >50% (86%/93%), Delta calcium > or =395 pg/mL (54%/100%), and Delta calcium >50% (78%/83%). A systematic analysis of the sensitivity and specificity of other possible criteria for a positive secretin or calcium test allowed us to identify a new criterion for secretin testing (Delta > or =120 pg/mL) with the highest sensitivity/specificity (94%/100%) and to confirm the commonly used criterion for calcium tests (Delta > or =395 pg/mL) (62%/100%). This analysis further showed that the secretin test was more sensitive than the calcium test (94% vs. 62%). Our results suggest that secretin stimulation should be used as the first-line provocative test because of its greater sensitivity and simplicity and lack of side effects. In ZES patients with a negative secretin test, 38%-50% have a positive calcium test. Therefore the calcium test should be considered in patients with a strong clinical suspicion of ZES but a negative secretin test. Furthermore, we found that some clinical (diarrhea, duration of medical treatment), laboratory (basal acid output), and tumoral (size, extent) characteristics correlate with the serum gastrin increase post secretin and post calcium. However, using the proposed criteria, the result of these provocative tests (that is, positive or negative) is minimally influenced by these factors, so secretin and calcium provocative tests are reliable in patients with different clinical, laboratory, and tumor characteristics. A systematic analysis of meal testing showed that 54%-77% of ZES patients have a <50% postprandial serum gastrin increase. However, 9%-20% of ZES patients had a >100% increase post meal, causing significant overlap with antral syndromes. Furthermore, we could not confirm the usefulness of meal tests for localization of duodenal gastrinomas. We conclude that the secretin test is a crucial element in the diagnosis of most ZES patients, the calcium test may be useful in selected patients, but the meal test is not helpful in the management of ZES. For secretin testing, the criterion with the highest sensitivity and specificity is an increase of > or =120 pg/mL, which should replace other criteria commonly used today.

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.

Serum gastrin in Zollinger-Ellison syndrome: I. Prospective study of fasting serum gastrin in 309 patients from the National Institutes of Health and comparison with 2229 cases from the literature

The assessment of fasting serum gastrin (FSG) is essential for the diagnosis and management of patients with the Zollinger-Ellison syndrome (ZES). Although many studies have analyzed FSG levels in patients with gastrinoma, limited information has resulted from these studies because of their small size, different methodologies, and lack of correlations of FSG levels with clinical, laboratory, or tumor features in ZES patients. To address this issue, we report the results of a prospective National Institutes of Health (NIH) study of 309 patients with ZES and compare our results with those of 2229 ZES patients in 513 small series and case reports in the literature. In the NIH and literature ZES patients, normal FSG values were uncommon (0.3%-3%), as were very high FSG levels >100-fold normal (4.9%-9%). Two-thirds of gastrinoma patients had FSG values <10-fold normal that overlap with gastrin levels seen in more common conditions, like Helicobacter pylori infection or antral G-cell hyperplasia/hyperfunction. In these patients, FSG levels are not diagnostic of ZES, and gastrin provocative tests are needed to establish the diagnosis. Most clinical variables (multiple endocrine neoplasia type 1 status, presence or absence of the most common symptoms, prior medical treatment) are not correlated with FSG levels, while a good correlation of FSG values was found with other clinical features (prior gastric surgery, diarrhea, duration from onset to diagnosis). Increasing basal acid output, but not maximal acid output correlated closely with increasing FSG. Numerous tumoral features correlated with the magnitude of FSG in our study, including tumor location (pancreatic > duodenal), primary size (larger > smaller) and extent (liver metastases > local disease). In conclusion, this detailed analysis of FSG in a large number of patients with ZES allowed us to identify important clinical guidelines that should contribute to improved diagnosis and management of patients with ZES.

Surgery increases survival in patients with gastrinoma

OBJECTIVE

To determine whether the routine use of surgical exploration for gastrinoma resection/cure in 160 patients with Zollinger-Ellison syndrome (ZES) altered survival compared with 35 ZES patients who did not undergo surgery.

SUMMARY BACKGROUND DATA

The role of routine surgical exploration for resection/cure in patients with ZES has been controversial since the original description of this disease in 1955. This controversy continues today, not only because medical therapy for acid hypersecretion is so effective, but also in large part because no studies have shown an effect of tumor resection on survival.

METHODS

Long-term follow-up of 160 ZES patients who underwent routine surgery for gastrinoma/resection/cure was compared with 35 patients who had similar disease but did not undergo surgery for a variety of reasons. All patients had preoperative CT, MRI, ultrasound; if unclear, angiography and somatostatin receptor scintigraphy since 1994 to determine resectability. At surgery, all had the same standard ZES operation. All patients were evaluated yearly with imaging studies and disease activity studies.

RESULTS

The 35 nonsurgical patients did not differ from the 160 operated in clinical, laboratory, or tumor imaging results. The 2 groups did not differ in follow-up time since initial evaluation (range, 11.8-12 years). At surgery, 94% had a tumor removed, 51% were cured immediately, and 41% at last follow-up. Significantly more unoperated patients developed liver metastases (29% vs. 5%, P = 0.0002), died of any cause (54 vs. 21%, P = 0.0002), or died a disease-related death (23 vs. 1%, P < 0.00001). Survival plots showed operated patients had a better disease-related survival (P = 0.0012); however, there was no difference in non-disease-related survival. Fifteen-year disease-related survival was 98% for operated and 74% for unoperated (P = 0.0002).

CONCLUSIONS

These results demonstrate that routine surgical exploration increases survival in patients with ZES by increasing disease-related survival and decreasing the development of advanced disease. Routine surgical exploration should be performed in ZES patients.

[Zollinger-Ellison syndrome]

The preoperative localization of gastrinomas often fails despite all modern imaging methods. Therefore, after biochemical confirmation of the diagnosis and exclusion of diffuse metastases, a meticulous surgical exploration including intraoperative ultrasound (IOUS) and duodenal exploration after duodenotomy should be performed. The experienced surgeon will be able to identify more than 90% of the primary tumors. Depending on the localization, excision of the tumor in the duodenal wall or enucleation from the pancreatic head should be performed. If the tumor is localized in the tail of the pancreas, distal pancreatectomy is the treatment of choice. Complete resection of the tumor is the only curative approach for the patients. For MEN-1 gastrinomas a spleen-preserving distal pancreatectomy with enucleation of tumors of the pancreatic head and duodenotomy with excision of duodenal gastrinomas should be performed. If the source of gastrin secretion can be regionalized to the pancreatic head by a preoperative SASI angiography, a pylorus-preserving partial pancreaticoduodenectomy might be the treatment of choice.

Optimal Treatment of Zollinger-Ellison Syndrome and Related Conditions in Elderly Patients

Zollinger-Ellison syndrome is characterised by refractory peptic ulcer disease, severe diarrhoea and gastric acid hypersecretion associated with an islet-cell tumour of the pancreas (gastrinoma). The true incidence and prevalence of this rare disease is unknown; in the US, the frequency is one per one million people and the age at presentation varies from 7 to 90 years. Zollinger-Ellison syndrome is sporadic in 62-80% of cases and in 20-38% of cases is associated with multiple endocrine neoplasia type 1 (MEN 1). The diagnosis of Zollinger-Ellison syndrome is certain when the plasma gastrin is >1000 pg/mL and the basal acid output is >15 mEq/h in patients with an intact stomach, >5 mEq/h in gastrectomised patients, or when this hypergastrinemia is associated with a pH <2. The treatment is based on control of gastric acid hypersecretion and of the malignant tumour and its possible metastases. Proton pump inhibitors are the most effective antisecretory drugs and can be administered in the elderly at high dosages without drug-related adverse effects. As an initial therapy, daily dosages of omeprazole 80-100 mg or pantoprazole 40-160 mg are employed. In long-term treatment the doses can be greatly reduced once effective control of the gastric output has been established. Intravenous proton pump inhibitors may be administered when patients cannot take oral therapy, particularly in acute conditions. All sporadic localised gastrinomas should be excised if possible. When liver metastases are also present, their debulking may improve symptoms and survival, and facilitate medical treatment. There is some controversy as to the surgical approach for gastrinomas associated with MEN 1. Somatostatin analogues can be useful in reducing gastric acid hypersecretion, serum gastrin and gastric enterochromaffin-like (ECL) cells and can thus contribute to treating the disease more effectively. Their antiproliferative effect can be used in treating liver metastases. Chemotherapy is not the therapy of choice in patients with gastrinomas and is indicated only in those with malignant progressive disease; interferon alpha, embolisation and chemoembolisation are not advisable for the elderly. The treatment of elderly Zollinger-Ellison syndrome patients, similarly to all elderly oncological patients, should be based on the use of comprehensive geriatric assessment. This will enable the clinician to define the functional status of the elderly person, to decide whether the patient can tolerate surgery and/or the stress of antineoplastic therapy, and finally, to determine whether this patient can tolerate an aggressive treatment for Zollinger-Ellison syndrome or whether the only possible choice is palliative relief of symptoms.

Somatostatin analogues in the treatment of endocrine tumors of the gastrointestinal tract

Somatostatin and its long-acting analogues have been introduced for the treatment of endocrine tumours of the gastrointestinal tract as they have been shown to effectively control symptoms resulting from excessive hormone release in patients with carcinoid, Verner-Morrison and glucagonoma syndromes. This beneficial effect is due to the presence of somatostatin receptors in high densities on the majority of endocrine tumours. The symptomatic effect is less pronounced in insulinomas, since 30 - 50% of these tumours lack or express only a few somatostatin receptors. With respect to symptomatic control, somatostatin receptor subtypes 2 and 5 are the most important and the currently available long-acting analogues octreotide and lanreotide bind preferentially to these receptor subtypes. Long-term studies have shown that somatostatin analogues are safe and that the most important adverse advent is the development of gallstones. The antiproliferative potency of somatostatin and its analogues in vitro and in experimental tumour models prompted a number of studies in patients with metastatic endocrine tumours that are generally unresponsive to conventional chemotherapeutic protocols. Stabilisation of tumour growth lasting for months to a few years was the most favourable result, occurring in 30 - 70% of patients. However, definite proof of antiproliferative potency in man is still pending since placebo-controlled studies are not available. Radioligand therapy based on 111Indium, 90Yttrium and 177Lutetium coupled to somatostatin analogues via bifunctional chelators is currently under investigation with promising data concerning long-lasting control of symptoms and tumour growth from Phase I trials.

Gastrin stimulates beta-cell neogenesis and increases islet mass from transdifferentiated but not from normal exocrine pancreas tissue

It is still unclear which factors regulate pancreatic regeneration and beta-cell neogenesis and which precursor cells are involved. We evaluated the role of intravenously infused gastrin in regenerating pancreas of duct-ligated rats. The ligation of exocrine ducts draining the splenic half of the pancreas resulted in acinoductal transdifferentiation within the ligated part but not in the unligated part. We found that infusion of gastrin from day 7 to 10 postligation resulted in a doubling of the beta-cell mass in the ligated part as measured by morphometry. This increase in insulin-expressing cells was not associated with increased proliferation, hypertrophy, or reduced cell death of the beta-cells. Furthermore, we found an increased percentage of single, extra-insular beta-cells and small beta-cell clusters induced by gastrin infusion. These changes occurred only in the ligated part of the pancreas, where transdifferentiation of the exocrine acinar cells to ductlike cells (metaplasia) had occurred, and was not found in the normal unaffected pancreatic tissue. In conclusion, we demonstrate that administration of gastrin stimulates beta-cell neogenesis and expansion of the beta-cell mass from transdifferentiated exocrine pancreas.

Gastric secretion in Zollinger-Ellison syndrome. Correlation with clinical expression, tumor extent and role in diagnosis--a prospective NIH study of 235 patients and a review of 984 cases in the literature

We prospectively studied 235 patients with Zollinger-Ellison syndrome (ZES) (205 without and 30 with prior acid-reducing surgery) and compared the results with 984 patients from 182 reports in the literature. The aims of the study were to evaluate the sensitivity of proposed acid secretory criteria for the diagnosis of ZES, propose new criteria, evaluate the variability and methodology of gastric secretory testing, and correlate the symptoms and signs of ZES, tumor extent, and primary tumor size and location with the degree of gastric acid hypersecretion. Multiple endocrine neoplasia-type 1 (MEN1) occurred in 22% of patients. The mean basal acid output (BAO) in patients without and with prior acid-reducing surgery was 41.2 +/- 1.7 mEq/hr (range, 1.6-118.3 mEq/hr) and 27.6 +/- 3.5 mEq/hr (range 5.9-102.9 mEq/hr), respectively. In patients with MEN1, those with female gender, Hispanic, or Asian race had lower BAOs. Diarrhea, esophageal stricture, and pyloric scarring were associated with a higher BAO. Neither other symptoms nor the tumor extent, primary tumor location, or size correlated with the magnitude of acid hypersecretion. ZES diagnosis was delayed a mean of 5.5 +/- 0.4 yr. Patients who were misdiagnosed as having either Crohn or celiac disease had higher BAOs. The sensitivities from our study and the literature review of the proposed BAO criteria for the diagnosis of ZES in patients without previous gastric acid-reducing surgery were 91% and 90% for BAO > or = 15 mEq/hr, 86% and 82% for BAO > or = 18 mEq/hr, 69% and 67% for BAO > 25 mEq/hr, and < 60% for BAO > 31 mEq/hr, respectively. The specificities of all the proposed BAO criteria were high. Both the criterion of BAO > or = 15 mEq/hr and BAO > or = 18 mEq/hr had good specificities and equal sensitivity. With prior acid-reducing surgery, the sensitivities in our study and from the literature review were 100% and 81% for BAO > or = 5 mEq/hr, 73% and 45% for BAO > 14.4 mEq/hr, and 37% and 31% for BAO > 19.2 mEq/hr, respectively. The reported mean specificity for the criterion of BAO > or = 5 mEq/hr was 85%, while it was 100% for the other 2 criteria. The maximal acid output (MAO) criterion of > 70 mEq/hr had sensitivities in the present National Institutes of Health (NIH) study and the literature review of 39% and 31%, respectively, and the criterion of MAO > 100 mEq/hr had a sensitivity of < 15% in patients with no prior acid-reducing surgery. The proposed criterion of BAO/MAO ratio > 0.6 had a low sensitivity. The proposed criterion of the ratio of basal and maximal acid H+ concentration (BAC/MAC ratio) > or = 0.6 had an excellent sensitivity-- > or = 89% in patients with or without previous acid-reducing surgery. The reported specificity for both the BAO/MAO criterion and the BAC/MAC criterion were similar, but BAC/MAC had a better sensitivity. Combination criteria of BAO generally did not improve sensitivity. The criterion of pH < or = 1 was met by only 27% of patients, and pH < or = 0.96 by 21% of patients with previous acid-reducing surgery. For patients with MEN1 with no prior acid-reducing surgery, the sensitivities were lower compared with patients with the sporadic form of ZES. The mean gastric volume in patients without prior acid-reducing surgery was 314 +/- 10 mL/hr and 247 +/- 25 mL/hr in patients with prior acid-reducing surgery. A basal volume criteria of > 160 mL/hr in patients without prior acid-reducing surgery occurred in > 86% of patients, and > 140 mL/hr in 87% of patients with prior acid-reducing surgery; these, thus, are neglected findings that have good sensitivities. Our analysis shows criteria based on MAO, pH, and BAO/MAO ratio do not have high sensitivities and thus are not useful. In patients without prior acid-reducing surgery, the criteria of BAO > or = 15 mEq/hr, BAC/MAC ratio > or = 0.6, and basal gastric volume > 160 mL/hr are useful for the diagnosis of ZES and have good specificities. In patients with prior acid-reducing surgery, the criteria of BAO > or = 5 mEq/hr, BAC/MAC ratio > or = 0.6, and basal gastric volume > 140 mL/hr have high sensitivities. In patients with sporadic ZES without acid-reducing surgery, the criterion of BAO > or = 18 mEq/hr is recommended as it has a similar sensitivity but higher specificity than the criterion of BAO > or = 15 mEq/hr. Only 1 patient in either data set (NIH or the literature) with or without previous acid-reducing surgery had a basal gastric pH > 2, therefore this finding essentially excludes the diagnosis of ZES. Gastric secretory measurements for 30 minutes, but not 15 minutes, give results comparable to those for a full hour. On the basis of these results, a number of gastric secretory criteria are proposed, including some for the first time, and alterations in methodology are proposed that should prove useful in the diagnosis of ZES.

Review article: gastrin and colorectal cancer

The polypeptide hormone gastrin was identified nearly a hundred years ago and its role in the regulation of acid secretion is well established. Gastrin also acts as a growth factor and is trophic for the normal gastric oxyntic mucosa. This growth promoting action has led to the extensive investigation of its role in carcinogenesis, in particular colorectal neoplasia. The relationship between gastrin and colorectal adenocarcinoma has been subject to controversy, however the findings from several recent studies have resulted in a clearer understanding of the mechanism of action of gastrin in this is common cancer. The majority of colorectal cancers produce their own gastrin, which may act in an autocrine manner. The tumour cells also express gastrin/CCKB receptors (and/or a combination of isoforms) which mediate the proliferative action. This locally produced gastrin gives rise to a small increase in systemic gastrin levels. Autocrine gastrin may also have a role in tumour development, as expression occurs early in the adenoma-carcinoma sequence. In addition, several studies using animal models have shown that systemic hypergastrinaemia promotes the proliferation of both normal and neoplastic colonic epithelium. Hyperproliferative colonic epithelium in the presence of hypergastrinaemia has been recorded in humans and a well-designed epidemiological study has demonstrated an increased incidence of colorectal cancer. Gastrin is a potential therapeutic target in the treatment of colorectal cancer and several approaches have been assessed. Receptor antagonists and antisecretory agents have been demonstrated to be ineffectual. Novel methods of inhibition, including the use of anti-gastrin antibodies, are currently being evaluated.

[Drug therapy of endocrine neoplasms. Part II: Malignant gastrinomas, insulinomas, glucagonomas, carcinoids and other tumors]

BACKGROUND

The thyroid gland and the adrenal glands are the most common sites of endocrine carcinomas (see Part I of this review, Med Klin 2000;95: 20-5, Nr. 1). Less frequent are endocrine malignancies of the gastrointestinal tract (gastrinomas, insulinomas, glucagonomas, carcinoids and others).

TREATMENT

Because of the rarity and missing prospective studies as well as radiotherapy and chemotherapy resistance of these tumors, generally accepted conventional therapy guidelines for these endocrine carcinomas do not exist. Surgery and radionucleotide treatment should be considered as first line therapy. Somatostatin analogs (octreotide) are frequently used as well. Chemotherapy is usually not effective. Common substances are streptozotocin, 5-fluorouracil, doxorubicin, dacarbazine and cyclophosphamide.

Protocol for the examination of specimens from patients with endocrine tumors of the pancreas, including those with mixed endocrine and acinar cell differentiation: a basis for checklists. Cancer Committee of the College of American Pathologists

No Abstract Available

Gastrointestinal endocrine tumours. Gastrinoma

Since the description of the Zollinger-Ellison syndrome in two patients in 1955, there have been significant advances in the understanding of its pathogenesis, natural history, relationship to multiple endocrine neoplasia type 1, diagnosis, methods of tumour localization and management. The main focus in treatment is now shifting from management of the gastric acid hypersecretory state which can now be controlled medically in almost every patient, to the management of the gastrinoma. Recent studies are beginning to provide insights into the natural history of gastrinomas, factors that are associated with invasiveness in some gastrinomas, defining the role of surgery in managing patients with different disease extents, or with MEN 1 and being able to provide insights into molecular abnormalities that may be important in their pathogenesis. In this article each of these advances is briefly reviewed with emphasis primarily on recent advances.

Differentiation between multiple liver hemangiomas and liver metastases of gastrinomas: value of enhanced MRI

PURPOSE

Hepatic metastases of neuroendocrine tumors are known to mimic hemangiomas on nonenhanced SE MR sequences. The usefulness of MR examination with gadolinium injection to identify lesions was prospectively evaluated.

METHOD

Nine patients with multiple liver metastases of gastrinomas were compared with six patients showing multiple liver hemangiomas. Patients underwent unenhanced T2-weighted SE, T1-weighted SE, and FLASH sequences, followed by enhanced sequential FLASH sequences and a 5 min delayed T1-weighted SE sequence.

RESULTS

On T2-weighted SE sequence, all hemangiomas displayed the same typical morphology as a sharply defined, homogeneous, high signal intensity lesion, but this pattern was also observed for some or all of the lesions in seven of nine patients with gastrinoma metastases. Dynamic FLASH sequences were accurate for lesions larger than 2 cm, hemangiomas displaying a nodular peripheral enhancement with centripetal filling in, and metastases displaying either an initial homogeneous or a regular peripheral enhancement. Precise assessment of lesions smaller than 2 cm remained equivocal. Delayed T1-weighted. SE sequence (performed at least 5 min after Gd-chelate injection) was the most accurate technique to identify metastases by showing hypo- or isointensity signal, whereas all hemangiomas were hyperintense.

CONCLUSION

Postcontrast delayed T1-weighted sequence is the primary technique to differentiate equivocal cases of hemangiomas from metastases of gastrinoma.

Tumors of the endocrine/neuroendocrine system: an overview

For the sake of discussion, the markedly diversified tumors of the endocrine/neuroendocrine system are classified as those originating in classic epithelial endocrine organs (eg, adrenal cortical adenomas), from the diffuse endocrine cells (eg, jejunal carcinoid tumors), or from clusters of these cells (eg, islet cell tumors); and those arising from neurosecretory neurons (eg, neuroblastoma) or paraganglia (eg, carotid body tumor). Although traditional transmission electron microscopy is useful for identifying neurosecretory or endosecretory granules as such, with few exceptions (eg, insulin-containing granules with a complex paracrystalline core) it is not possible to ascribe a granule type (size, shape, or ultrastructure) to a distinct nosologic entity or secretory product because of their overlapping fine structures in different cell types. Immunoelectron microscopy methods utilizing colloidal gold-labeled secondary antibodies can be used to localize virtually any antigen (peptide or neuroamine) to a specific neurosecretory or endosecretory granule or other cell structure. General endocrine/neuroendocrine cell markers such as neuron-specific enolase, the chromogranins, and synaptophysin are useful in identifying neuroendocrine differentiation in a neoplasm using routine immunohistochemical procedures. The current relevance of the APUD concept of Pearse as well as the biologic importance of endocrine/neuroendocrine secretory products such as bombesin and insulinlike growth factors also are discussed.

Flow cytometry and Zollinger-Ellison syndrome: relationship to clinical course

BACKGROUND

With successful means of controlling gastric acid secretion in patients with Zollinger-Ellison syndrome, the gastrinoma itself is becoming the major determinant of long-term survival. No methods have yet been described to predict which tumors will have more malignant courses thereby indicating which patients should undergo aggressive surgery or antitumor therapy. Because DNA analysis, using flow cytometry, has proved helpful in this regard in other tumors, the current study was designed to evaluate its utility in gastrinoma patients.

METHODS

Flow cytometry was performed on 81 paraffin-embedded gastrinoma specimens from 59 patients. Results were compared with preoperative patient characteristics, findings at surgery, and postoperative follow up.

RESULTS

Tumors were diploid in 54% of patients, near diploid in 15%, pure tetraploid in 0%, nontetraploid aneuploid in 25%, and multiple stem line aneuploid in 5%. All patients with multiple stem line aneuploid tumors had wide-spread metastases whereas all patients with nontetraploid aneuploid tumors had localized or regional disease. Median S phase percentage was 3.6. S phase percentages were higher in patients with widespread metastatic disease than in patients with localized or regional disease. Disease extent also correlated closely with fasting serum gastrin level. After removing this variable with logistic regression analysis, the significant correlation between disease extent and DNA analysis persisted.

CONCLUSIONS

DNA analysis of gastrinoma tissue specimens correlates independently with the extent of disease and may be useful in planning therapeutic strategies for patients with Zollinger-Ellison syndrome.

Assessment and prediction of long-term cure in patients with the Zollinger-Ellison syndrome: the best approach

OBJECTIVE

To identify the best method for determining freedom from disease after gastrinoma resection and for predicting long-term disease-free status in patients with the Zollinger-Ellison syndrome.

DESIGN

Prospective study in consecutive patients.

SETTING

Referral-based clinical research center.

PATIENTS

Eighty-one consecutive patients with the Zollinger-Ellison syndrome who underwent surgical exploration for gastrinoma resection.

INTERVENTION

Patients were evaluated after gastrinoma resection, before discharge, 3 to 6 months after surgery, and yearly thereafter. Evaluation included secretin provocative testing and fasting serum gastrin determinations. Follow-up examinations after the initial postoperative evaluations included a clinical assessment, acid secretion studies, a calcium provocative test, and various imaging studies.

MEASUREMENTS AND MAIN RESULTS

Most patients (96%) had gastrinomas. Freedom from disease was defined by improved symptoms, reduced acid output and antisecretory drug requirements, and a normal gastrin level, normal imaging studies, and negative gastrin provocative studies. Fifty-two percent of patients (n = 42) were disease-free immediately after surgery, 44% at 3 to 6 months, 42% at 1 year, and 35% by 5 years (mean follow-up, 39 months). The secretin provocative test was the first test to become positive in 45% of patients with a recurrence, the serum gastrin determination was the first test to become positive in 36%, and both tests became positive at the same time in 18%. No recurrence was first detected by imaging studies or by calcium provocative testing. Fasting serum gastrin levels and secretin provocative test results at different postoperative times can be used to predict the probability of a patient remaining disease free at 3 years. Patients with a normal gastrin level and a normal secretin provocative test immediately after surgery had a 3-year disease-free probability of 75%, and normal results on both tests at 6 months, 1 year, and 2 years yielded respective probabilities of 88%, 95%, and 100%.

CONCLUSIONS

Both the secretin provocative test and fasting serum gastrin determination are necessary for the early diagnosis of cases of recurrent disease after gastrinoma resection. The calcium provocative test and imaging studies do not detect any recurrences first. Fasting serum gastrin determinations and secretin provocative testing at different postoperative times can be used to predict the probability of a patient remaining disease free at 3 years.

Pathologic aspects of gastrinomas in patients with Zollinger-Ellison syndrome with and without multiple endocrine neoplasia type I

During the three decades since the recognition of the Zollinger-Ellison syndrome (ZES), major progress has been made in the diagnosis and treatment of this disease. However, the many failed operations in patients with ZES, the existence of primary lymph node gastrinomas, and the surgical approach of patients with ZES and multiple endocrine neoplasia type I (MEN-I) have remained controversial issues. In this review, our experience with the pathology of immunocytochemically identified gastrinomas in 44 patients with ZES is presented and related to the relevant literature. (1) Gastrinomas occur frequently in the duodenum (> 40%) and are commonly small (< 1 cm). They can therefore easily be missed at surgical exploration; lymph node metastases from such occult gastrinomas may be mistaken for primary tumors. (2) Most pancreatic gastrinomas reside in the head of the gland and have a diameter of 1 to 3 cm. (3) Gastrinomas associated with MEN-I are predominantly of duodenal origin and frequently multicentric; sporadic gastrinomas are single and more often pancreatic. Because MEN-I associated pancreatic tumors seldom contain gastrin, ZES in MEN-I patients is almost never cured by resection of the pancreatic tumors. (4) The metastatic potential of most small duodenal gastrinomas seems to be restricted to the regional lymph nodes.

Detection of gastrin and its messenger RNA in Zollinger-Ellison tumors by non-radioactive in situ hybridization and immunocytochemistry

Gastrin immunocytochemistry and non-radioactive in situ hybridization, using biotinylated oligonucleotide probes, for gastrin mRNA have been used for studying a retrospective material of six gastrin-producing (Zollinger-Ellison) tumors. Hybridization results for gastrin mRNA were positive in all six, while gastrin immunoreactivity could be detected in five tumors. In one of the patients, different areas of the same tumor displayed differences in immunoreactivity to gastrin, but were uniformly hybridization positive. Weak hybridization signals were detected in liver metastases from a necropsy case, while the gastrin immunostaining was more pronounced. The results show that non-radioactive hybridization methods are applicable to routine clinical specimens stored for as long as 16 years and that in situ hybridization may be a useful complement to immunocytochemical diagnosis, particularly in cases where high synthesis and little storage of hormonal products occur.

Endocrine neoplasms of the pancreas: a clinicopathologic study of 24 cases and immunohistochemical remarks

A total of 24 patients with endocrine neoplasms of the pancreas were clinicopathologically and immunohistochemically studied. They consisted of 18 patients with adenoma and 6 with carcinoma. Of the 24 patients, 13 developed attacks of hypoglycemia due to hyperinsulinemia, and 1 developed an uncontrollable duodenal ulcer caused by the hypersecretion of gastrin, however, the remaining 10 were asymptomatic. No prediction could be made as to the site of origin of the tumors. A clear difference was seen between adenoma and carcinoma in the size of the mass, the mean greatest diameter of the 18 adenoma cases being 1.7 cm, while that of the 6 carcinoma cases was 7.3 cm. One of the 13 insulinomas and a gastrinoma was malignant, while all 24 tumors were positive for neuron-specific enolase. The 13 insulinomas were diffusely positive for insulin and 5 were also shown to be focally immunoreactive for gastrin, with 3 also being immunoreactive for somatostatin and 2 for pancreatic polypeptide. The gastrinoma showed immunoreactivity for somatostatin, insulin, pancreatic polypeptide, and glucagon in addition to a positivity to gastrin. The above findings thus indicate the multiple hormone synthesis of endocrine neoplasms of the pancreas.

Curative resection in Zollinger-Ellison syndrome. Results of a 10-year prospective study

Since 1980, 73 patients with Zollinger-Ellison syndrome (ZES) without radiographic evidence of liver metastases were studied on a prospective protocol including medical management of gastric acid hypersecretion, extensive radiographic tumor localization, and exploratory surgery to find and resect gastrinoma for potential cure. Each patient had gastric acid hypersecretion effectively controlled with either H2-blockers or omeprazole. Patients were divided prospectively into two groups, with all patients undergoing the same preoperative localization studies and extensive laparotomy. In contrast to group 1 (1980-1986) (36 patients), group 2 (1987-Oct. 1990) (37 patients) also underwent additional procedures (transillumination and duodenotomy) at surgery to find duodenal gastrinomas. Preoperative imaging studies localized tumor in 38 (52%) patients, and portal venous sampling for gastrin determinations was positive in 49 (67%) patients. Gastrinomas were found and resected in 57 (78%) patients. Significantly more gastrinomas (92% of patients) were found in group 2 than in group 1 patients (64%) (p less than 0.01). This increase was due to increased numbers of duodenal gastrinomas in group 2 than in group 1 patients (43% versus 11%; p less than 0.01). The increased ability to find duodenal gastrinomas did not significantly improve the immediate disease-free rate, which was 58% for all patients. Duodenal primary gastrinomas were found to have a significantly greater incidence of metastases (55%) and a significantly shorter disease-free interval (12 months) than pancreatic gastrinomas (22% and 84 months, respectively) suggesting that duodenal gastrinomas may be more malignant and not more frequently curable than pancreatic gastrinomas. Operations were performed with no deaths and 11% morbidity rate. Long-term follow-up showed that 50% of patients initially rendered disease free would develop recurrent disease by 5 years. Survival was excellent for all patients, and none died of malignant spread of the tumor or uncontrolled peptic ulcer disease, with a mean follow-up of 5 years. This finding is in contrast to patients who presented with metastatic disease on imaging studies and had a 20% 5-year survival rate. This study suggests that all patients with localized sporadic ZES can have the gastric acid hypersecretion managed medically, that overall survival of these patients is excellent, most (78%) can have all gastrinoma found and resected, and some (30%) will be cured (long-term disease-free survival).

Parathyroid gastrin and parathormone-producing tumour in the Zollinger-Ellison syndrome of MEN 1 origin

A case of Zollinger-Ellison syndrome of multiple endocrine neoplasia type 1 (MEN 1) origin with hyperparathyroidism and with a rise in serum gastrin due to an unusual parathyroid "gastrinoma" has been investigated. The patient had multiple endocrine tumours (pituitary and parathyroid), but no evidence of pancreatic or duodenal gastrin-producing neoplasm. Radio-immunoassay, immunohistochemistry and electron microscopy showed gastrin in one parathyroid adenoma. These findings, together with a decrease of gastrinaemia after parathyroidectomy suggest that true gastrin was produced by parathyroid tumour cells and that they themselves may be the origin of the hypergastrinaemia. Our ultrastructural investigation extends these observations and the results are discussed.

Zollinger-Ellison syndrome

As clinical experience with patients with ZES has grown, increasing recognition has been made of the broad spectrum of symptoms associated with gastrinomas. Diarrhea and acid-induced esophageal injury have taken their place alongside chronic peptic ulcer disease as indications for screening for gastrinoma. Diagnostic testing should begin with fasting serum gastrin levels and should include intravenous secretin infusion if fasting serum levels of gastrin are nondiagnostic and the patient is not found to be hypochlorhydric. Tumor localization is critical to aid in the identification of patients with potentially curable localized disease. Preoperative evaluation utilizing CT scanning with intravenous contrast should be done early and should be supplemented by other imaging modalities as necessary. Exploratory laparotomy, including a thorough examination of the duodenum and perhaps intraoperative ultrasound, should be performed in all patients with sporadic gastrinoma who lack evidence of extensive metastatic disease on preoperative evaluation. By utilizing this approach, it is likely that at least 20% of patients with ZES can be cured. With the availability of the highly effective H(+)-K(+)-ATPase inhibitor omeprazole, excellent control of symptoms related to gastric acid hypersecretion can be expected. Patients with unresectable gastrinoma may thus avoid potentially morbid antisecretory surgery and be managed with a fairly simple medical regimen. Further developments in the chemotherapeutic management of these patients with unresectable disease should be forthcoming in the future.

Clinical pathology of endocrine tumors of the pancreas. Analysis of autopsy cases

A clinicopathological analysis of endocrine tumors of the pancreas, using 800 autopsy cases (422 men, 378 women, mean age 78.7) was accomplished. The results were: (1) Endocrine tumors and similar lesions were found in 3% or 24 cases (25 lesions). Twenty lesions (20 cases) were found to be tumors and five lesions (five cases) were determined to be hyperplasia of Langerhans islets. (2) Incidence of tumor was 10% (6/60) in individuals having histological studies of all sections of the pancreas, and 1.6% (12/738) in individuals having histological studies of three random sections of the pancreas. (3) None of the cases with tumors and hyperplastic lesions showed symptoms of hormone production. (4) Immunohistochemical analysis revealed hormone production in all 20 tumor cases and multiple hormone production was found in 14 of these (70%). (5) Ductular or tubular structures were found in or adjacent to the tumors in 12 cases (60%) and hyperplasia in one case (20%). Langerhans islets, 500 microns or larger in size, were found in three lesions of the tumor (15%). Langerhans islets with the mean diameter of normal islets + 2 SD or larger also were found around five tumors (25%) and three hyperplasias (60%). The above findings suggest that endocrine tumors of the pancreas are prevalent and that they do not produce symptoms of excessive hormone production even though they do continue to produce hormones. Some of the endocrine tumors or hyperplasias develop from totipotent stem cells of the duct epithelia, and factors promoting the growth of Langerhans islets might exist.

Multiple hormone elevations in Zollinger-Ellison syndrome. Prospective study of clinical significance and of the development of a second symptomatic pancreatic endocrine tumor syndrome

In the present study of 45 patients with Zollinger-Ellison syndrome, the frequency and clinical importance of the release of multiple gastrointestinal peptides were assessed prospectively. During an initial evaluation, extent of gastrinoma, clinical symptoms, disease duration, and presence or absence of multiple endocrine neoplasia, type I (MEN-I) were assessed. All patients had determinations of fasting plasma gastrin, human pancreatic polypeptide, motilin, neurotensin, and somatostatin; 35 had determinations of insulin and gastrin-releasing peptide and 21 had determinations of glucagon. A plasma elevation of additional peptides besides gastrin was detected in 62%, with 44% having one, 18% having two, and 0% having three additional peptides elevated. Motilin was elevated in 29%, human pancreatic polypeptide in 27%, neurotensin in 20%, and gastrin-releasing peptide in 10%, whereas insulin, glucagon, and somatostatin were not elevated in any patient. The presence or absence of elevation of any peptide did not differ in patients with or without MEN-I, with gastrinoma size, with the presence or absence of metastatic disease, or with various clinical symptoms. Patients were assessed yearly for clinical evidence of a secondary symptomatic pancreatic endocrine tumor syndrome with a median follow-up of 146 and 84 months from onset or diagnosis, respectively. Only one patient (2% of patients) developed a second syndrome (rate, 2 patients per 100 patients observed for 10 years). These results demonstrate that the plasma elevation of multiple gastrointestinal peptides is common in patients with Zollinger-Ellison syndrome; however, the rate of developing a second symptomatic pancreatic endocrine tumor syndrome is much lower than generally believed. Furthermore, no evidence is found to support the conclusions that the detection of the plasma elevation of these peptides is clinically important in assessing MEN-I status, disease extent, or presence of metastatic disease or that elevated levels of motilin, neurotensin, gastrin-releasing peptide, or human pancreatic peptide are associated with any distinct clinical symptoms. Therefore, we recommend that plasma concentrations of these additional gastrointestinal peptides should not be assessed routinely but rather only if new symptoms develop.

Classification and histogenesis of gastroenteropancreatic endocrine tumours

A series of 267 gastroenteropancreatic endocrine tumours has been revised from the point of view of histopathologic diagnosis, hormonal profile and clinical behaviour. Results of this investigation, together with revised concepts on the histogenesis of gastroenteropancreatic endocrine growths, allowed to develop detailed classification systems which proved useful for precise tumour diagnosis and for clinicopathologic correlation, with special reference to tumour function, prognosis and therapy. Among 132 pancreatic growths, various types of islet cell tumours (61 cases), with (45 cases) or without (16 cases) hyperfunctional syndrome, were separated from different types of gut-related (38 cases) and 'ectopic' (three cases) tumours, as well as from 25 non-functioning, locally symptomatic tumours, three small cell carcinomas and two mixed endocrine-exocrine tumours. Among 97 intestinal tumours, 39 argentaffin EC cell carcinoids, mostly from the appendix and ileum, were separated from 23 hindgut-type carcinoids, mostly from the rectum, 22 gastrin cell tumours, mainly from the duodenal bulb, five somatostatin cell tumours, mostly from the periampullary region of the duodenum, and two gangliocytic paragangliomas. Among 38 gastric tumours, five small cell 'neuroendocrine' carcinomas were separated from three gastrin cell tumours and 30 argyrophil carcinoids, 27 of which arose in the body fundus, 16 associated with chronic atrophic gastritis and four with combined Zollinger Ellison/Multiple Endocrine Neoplasia Syndrome.

Gastrin in non-neoplastic pancreatic tissue from patients with and without gastrinomas

Processing-independent radioimmunoanalysis for progastrin showed that extracts of normal pancreatic tissue from normal subjects (n = 5) and from patients with adenocarcinoma of the papilla of Vater (n = 4) contain progastrin and its products. The concentrations varied from 0.1 to 5.8 pmol/g tissue, of which carboxyamidated bioactive gastrins constituted 0.03-1.9 pmol/g. In histologically normal and nonneoplastic pancreatic tissue from patients with duodenal (n = 3) and pancreatic (n = 2) gastrinomas the expression of gastrin was significantly higher-14.5 pmol/g (median), of which 28% was bioactive amidated gastrins. Gastrin-17 was the main bioactive product, but its immediate precursor, glycine-extended gastrin-17, constituted the predominant part of the preprogastrin product in pancreatic tissue. Proper gastrinoma tissue contained several precursor forms, including intact unprocessed progastrin. Progastrins were also found in high concentrations in plasma from the gastrinoma patients. The results raise the possibility that increased expression of progastrin and its products in non-neoplastic pancreatic tissue is a primary defect predisposing to neoplasia.

Gastrinomas in the duodenums of patients with multiple endocrine neoplasia type 1 and the Zollinger-Ellison syndrome

In patients with multiple endocrine neoplasia type 1 (MEN-1), gastrinomas are common and thought to occur predominantly in the pancreas. We describe eight patients with MEN-1 and hypergastrinemia (seven with the Zollinger-Ellison syndrome) in whom we searched for neuroendocrine tumors in the pancreas and duodenum. Tumors were found in the proximal duodenum in all eight patients: solitary tumors (diameter, 6 to 20 mm) in three patients and multiple microtumors (diameter, 2 to 6 mm) in the other five. Paraduodenal lymph-node metastases were detected in four patients. Immunocytochemical analysis revealed the presence of gastrin in all the duodenal tumors and in their lymph-node metastases. In contrast, no immunoreactivity for gastrin was present in the endocrine tumors found in the seven pancreatic specimens available for study, except for one tumor with scattered gastrin-positive cells. In four of the six patients whose duodenal gastrinomas were removed, serum gastrin levels returned to normal; in the other two patients gastrin concentrations decreased toward normal. We conclude that in patients with MEN-1 and the Zollinger-Ellison syndrome, gastrinomas occur in the duodenum, but the tumors may be so small that they escape detection.

Gut endocrine and neural peptides

The once exponential growth in the number of new gut endocrine peptides being discovered has become slightly slower in recent years, and expansion of the field of gut hormones has involved mainly the application of new investigative methods. Some new peptides have been described and major inroads have been made into establishing the ontogeny of gut endocrine cells, the origins and pathways of the enteric innervation, and the involvement of the diffuse neuroendocrine system as a whole in disease states. Further insight is being gained into the functional activity of the peptide cell system by studying the control, sites and rates of peptide gene expression, and the localization and characterization of peptide binding sites on target cells.

Gastrinoma

The Zollinger-Ellison syndrome with its main symptom of massive gastric hypersecretion presents problems with both the medical and surgical approaches to treatment. Successful medical treatment depends on a life-long commitment to rigid medication schedules requiring careful ongoing supervision and is subject to pitfalls of compliance, drug side effects, drug resistance, and complications of persistent tumor growth. Surgical therapy carries risks of operative mortality and complications. If a low operative mortality can be maintained and the nutritional results after total gastrectomy are good, then it is the authors' opinion that the permanent relief from dangers of hypersecretion afforded by total gastrectomy makes surgery a worthwhile approach. Based on our operative experience in 34 patients and interpretation of the experience of others, we believe that resection of all tumor that can be resected, combined with total gastrectomy, is safe and dependable. The results compare well with those of long-term medical management.

Progastrin expression in mammalian pancreas

Expression and processing of progastrin were examined in fetal, neonatal, and adult pancreatic tissue from five mammalian species (cat, dog, man, pig, and rat). A library of sensitive, sequence-specific immunoassays for progastrin and its products was used to monitor extractions and chromatography before and after cleavage with processing-like enzymes. The results showed that progastrin and its products are expressed in the pancreas of all species in total concentrations varying from 0.3 to 58.9 pmol/g of tissue (medians). The degree of processing was age- and species-dependent. In comparison with adult pancreatic tissue the fetal or neonatal pancreas processed a higher fraction to bioactive, C-terminally amidated gastrin. Nevertheless, the pancreatic processing was always less complete than that of the adult antral mucosa. The moderate level of expression and the attenuated processing in the adult pancreas contribute to explain previous failures to detect gastrin in normal pancreatic tissue. Our results indicate that gastrin-producing tumors in the pancreas are not ectopic, but arise from cells that normally express the gastrin gene.

Prospective study of the standard meal provocative test in Zollinger-Ellison syndrome

PURPOSE

The purpose of this work was to evaluate the proposed usefulness of a standard meal-stimulated gastrin provocative test in: (1) distinguishing Zollinger-Ellison syndrome (ZES) from antral syndromes; (2) localizing duodenal gastrinomas; or (3) suggesting that patients with multiple endocrine neoplasia type I (MEN-I) may have an increased incidence of antral syndromes.

PATIENTS AND METHODS

Seventy-four consecutive patients with ZES referred to the National Institutes of Health were studied prospectively. The extent and location of gastrinomas, acid secretory studies, and the presence or absence of MEN-I were determined and correlated with the results of the gastrin response to standard meal provocative testing.

RESULTS

For patients with fasting serum gastrin levels less than 1,000 pg/mL (n = 43), only 44% had a less than 50% increase over the pre-meal value, which is reported to be the typical response in ZES, and 40% had a 50% to 99% increase. Furthermore 16% had a 100% or greater increase, 9% a 150% or greater increase, and 5% a 200% or greater increase, which overlaps with values reported to be characteristic of 98%, 92%, and 46% of patients with antral syndromes. Results did not differ for patients with or without MEN-I, depend on the extent of the gastrinoma (duodenal versus pancreatic gastrinomas), the presence of previous gastric surgery or type of gastric surgery, or for patients with fasting serum gastrin concentrations greater than or equal to 1,000 pg/mL or less than 1,000 pg/mL. studies of four patients before and after resection of the gastrinoma, who prior to surgery had a greater than 100% increase in gastrin secretion after the meal, demonstrated that all patients had a less than 100% increase postoperatively even though no gastric resection was done.

CONCLUSIONS

Approximately half of the patients with ZES have a greater than 50% increase in serum gastrin concentration following a standard test meal and one fifth have a 100% or greater increase. Therefore, they cannot be distinguished on this basis from patients with antral syndromes. The increased serum gastrin level after the meal in these patients with ZES appears to be due to the gastrinoma. Furthermore, the current study provides no evidence for the proposals that antral syndromes are more common in patients with MEN-I, that gastric surgery affects the meal response in patients with gastrinomas, or that the meal test is useful in localizing duodenal gastrinomas.

Zollinger-Ellison Syndrome in the Intensive Care Setting

Management of patients with Zollinger-Ellison syn drome differs markedly from management of patients with idiopathic gastric acid hypersecretion or routine peptic ulcer disease. Because of the possible complica tions arising from gastric acid hypersecretion or from complications caused by the gastrinoma itself, patients with these disorders frequently present to critical care physicians. It is important that critical care physicians be familiar with the acute presentation of patients with Zollinger-Ellison syndrome as well as the appropriate treatment. We review the important points pertaining to the recognition and treatment of Zollinger-Ellison syn drome in the acute care setting.

The role of morphometry in predicting prognosis in pancreatic islet cell tumors

Morphometry of 31 pancreatic islet cell tumors was examined to determine the value of this technique in assessing tumor behavior. Patients were followed for a mean period of 5.1 years (range, 1 month-14 years) after diagnosis. Initially 17 localized and nine metastatic tumors were studied. Discriminant analysis was carried out on these cases and identified nuclear/cytoplasmic ratio and number of nuclei/mm2 as the significant discriminatory features. These were combined to derive a classification rule which was capable of correctly identifying localized and metastatic tumors in 92% of cases. The classification rule was applied subsequently to an additional five test cases, all of which were classified successfully. The failure of increased nuclear size and pleomorphism to correlate with malignancy in these tumors was confirmed. Tumors which metastasized had significantly greater gross diameters than localized lesions, but overlap existed. Mitotic counts were not a helpful discriminatory feature. Morphometry may be useful in improving histologic assessment of pancreatic islet cell tumor behavior.