Atrophic gastritis and gastric carcinoid tumours

Insights into Effects/Risks of Chronic Hypergastrinemia and Lifelong PPI Treatment in Man Based on Studies of Patients with Zollinger-Ellison Syndrome

The use of proton pump inhibitors (PPIs) over the last 30 years has rapidly increased both in the United States and worldwide. PPIs are not only very widely used both for approved indications (peptic ulcer disease, gastroesophageal reflux disease (GERD), Helicobacter pylori eradication regimens, stress ulcer prevention), but are also one of the most frequently off-label used drugs (25–70% of total). An increasing number of patients with moderate to advanced gastroesophageal reflux disease are remaining on PPI indefinitely. Whereas numerous studies show PPIs remain effective and safe, most of these studies are <5 years of duration and little data exist for >10 years of treatment. Recently, based primarily on observational/epidemiological studies, there have been an increasing number of reports raising issues about safety and side-effects with very long-term chronic treatment. Some of these safety issues are related to the possible long-term effects of chronic hypergastrinemia, which occurs in all patients taking chronic PPIs, others are related to the hypo-/achlorhydria that frequently occurs with chronic PPI treatment, and in others the mechanisms are unclear. These issues have raised considerable controversy in large part because of lack of long-term PPI treatment data (>10–20 years). Zollinger–Ellison syndrome (ZES) is caused by ectopic secretion of gastrin from a neuroendocrine tumor resulting in severe acid hypersecretion requiring life-long antisecretory treatment with PPIs, which are the drugs of choice. Because in <30% of patients with ZES, a long-term cure is not possible, these patients have life-long hypergastrinemia and require life-long treatment with PPIs. Therefore, ZES patients have been proposed as a good model of the long-term effects of hypergastrinemia in man as well as the effects/side-effects of very long-term PPI treatment. In this article, the insights from studies on ZES into these controversial issues with pertinence to chronic PPI use in non-ZES patients is reviewed, primarily concentrating on data from the prospective long-term studies of ZES patients at NIH.

Composite adenocarcinoma and carcinoid gastric tumor in chronic atrophic gastritis and pernicious anemia

A 42-year-old Hispanic female was referred for investigation of unexplained weight loss. Initial upper endoscopy showed atrophic gastritis. Repeat endoscopy one year later revealed the presence of mixed composite tumor consisting of gastric adenocarcinoma and carcinoid tumors. Treatment was accomplished by surgical excision. Such cases are extremely rare and few such reports are available in the literature. We discuss the pathologies and means by which these tumors are classified and treated.

Five-year follow-up of patients treated for 1 year with octreotide long-acting release for enterochromaffin-like cell carcinoids

BACKGROUND

Gastric carcinoids type 1 (GC1) are neuroendocrine tumors (NETs) arising from the enterochromaffin-like (ECL) cells in patients with chronic atrophic gastritis (CAG). The treatment of GC1 has been endoscopic polypectomy or surgical tumor excision and antrectomy. One year treatment with somatostatin analogs (SSAs) diminished tumor load and ECL cell density. The effect persisted 1 year after treatment was discontinued. However, the optimal SSA dose and treatment duration are unknown.

OBJECTIVES

The aim of the present work was to study macroscopic and histopathological changes in the stomach and serum markers gastrin and chromogranin A (CgA) in GC1 patients 5 years after 1 year of octreotide long-acting release (LAR) treatment.

MATERIAL AND METHODS

Five patients with GC1 were included 5 years after the initial year of octreotide LAR treatment. All patients underwent upper gastrointestinal endoscopy including tumor and mucosal biopsies from oxyntic mucosa, chest and abdominal computer tomography and octreotide scintigraphy. Fasting serum gastrin and CgA were also measured.

RESULTS

At 5 years, one patient had a highly malignant gastric tumor, one patient had an increased number of GCs, regional and distant metastases and three patients had an increased number of GCs. Serum gastrin and CgA increased to pre-treatment levels after 1 year of follow-up and were unchanged at the 5-year follow-up.

CONCLUSIONS

The disease had progressed in all five GCs patients treated with octreotide for 12 months at 5 years of follow-up. This suggests that, if started, octreotide treatment should not be discontinued in these patients.

Cholecystokinin and gastrin receptors

Cholecystokinin and gastrin receptors (CCK1R and CCK2R) are G protein-coupled receptors that have been the subject of intensive research in the last 10 years with corresponding advances in the understanding of their functioning and physiology. In this review, we first describe general properties of the receptors, such as the different signaling pathways used to exert short- and long-term effects and the structural data that explain their binding properties, activation, and regulation. We then focus on peripheral cholecystokinin receptors by describing their tissue distribution and physiological actions. Finally, pathophysiological peripheral actions of cholecystokinin receptors and their relevance in clinical disorders are reviewed.

Upper gastrointestinal carcinoid tumors incidentally found by endoscopic examinations

AIM

This study shares Asian clinical experiences of carcinoid tumors that originated in the upper gastrointestinal tract.

METHODS

From May 1987 to June 2002, we had found only 13 cases of histologically confirmed carcinoid tumors in the upper gastrointestinal tract by endoscopic examinations. There were eight males and five females. The mean age was 53.16+/-20.51 years that ranged from 26 to 82 years. Each of their clinical presentations, locations, tumor morphology, and size and the treatment outcome were analyzed and discussed.

RESULTS

One patient had a polypoid lesion at the lower esophagus, nine were stomach lesions and three located at the duodenum. All patients with polypoid and submucosal tumor types were of small size (<1.7 cm) and all patients survived after simple excision or polypectomy. Four of the five patients in tumor mass forms died and the tumors were more than 2.0 cm in size.

CONCLUSION

Carcinoid tumors rarely originated from the upper gastrointestinal tract and are usually found accidentally after endoscopic study. Bigger size (more than 2 cm) tumor masses may indicate a more severe disease and poor prognosis.

Gastric carcinoids: biologic behavior and prognosis after differentiated treatment in relation to type

OBJECTIVE

To analyze tumor biology and the outcome of differentiated treatment in relation to tumor subtype in patients with gastric carcinoid.

BACKGROUND

Gastric carcinoids may be subdivided into ECL cell carcinoids (type 1 associated with atrophic gastritis, type 2 associated with gastrinoma, type 3 without predisposing conditions) and miscellaneous types (type 4). The biologic behavior and prognosis vary considerably in relation to type.

METHODS

A total of 65 patients from 24 hospitals (51 type 1, 1 type 2, 4 type 3, and 9 type 4) were included. Management recommendations were issued for newly diagnosed cases, that is, endoscopic or surgical treatment of type 1 and 2 carcinoids (including antrectomy to abolish hypergastrinemia) and radical resection for type 3 and 4 carcinoids.

RESULTS

Infiltration beyond the submucosa occurred in 9 of 51 type 1, 4 of 4 type 3, and 7 of 9 type 4 carcinoids. Metastases occurred in 4 of 51 type 1 (3 regional lymph nodes, 1 liver), the single type 2 (regional lymph nodes), 3 of 4 type 3 (all liver), and 7 of 9 type 4 carcinoids (all liver). Of the patients with type 1 carcinoid, 3 had no specific treatment, 40 were treated with endoscopic or surgical excision (in 10 cases combined with antrectomy), 7 underwent total gastrectomy, and 1 underwent proximal gastric resection. Radical tumor removal was not possible in 2 of 4 patients with type 3 and 7 of 9 patients with type 4 carcinoid. Five- and 10-year crude survival rates were 96.1% and 73.9% for type 1 (not different from the general population), but only 33.3% and 22.2% for type 4 carcinoids.

CONCLUSION

Subtyping of gastric carcinoids is helpful in the prediction of malignant potential and long-term survival and is a guide to management. Long-term survival did not differ from that of the general population regarding type 1 carcinoids but was poor regarding type 4 carcinoids.

Altered Distribution of Metaplastic Paneth, Gastrin and Pancreatic Acinar Cells in Atrophic Gastritic Mucosa with Endocrine Cell Lesions

The mechanism of progression from gastric endocrine cell hyperplasias (ECHs) to carcinoid tumor (GCT) is still unknown. In these lesions, the distribution of metaplastic Paneth, gastrin and pancreatic acinar cells developing due to consequences of corporal mucosal atrophy has not been investigated in detail. In this study, 33 gastric endoscopic biopsies with endocrine cell lesions were examined. In all cases except 6 with solitary GCT, complete-type (small intestine) intestinal metaplasia (IM) with Paneth cells was observed. The density of lysozyme-positive Paneth cells in IMs in cases with GCTs was less than those in ECH alone. The density of gastrin-positive cells in IMs and average number of micronodules of ECHs were similar. Pancreatic acinar metaplasia (PAM) was observed in 6 cases of GCTs with ECH. The size of GCTs with ECH was smaller than those without ECH. By image analysis, the percentage of Ki67 (MIB-1, proliferation marker) expressing cells of GCTs with ECH was 5.1+/-0.6%, and GCT without ECH 7.8+/-1%. Our results indicate that few Paneth cells and many PAMs in atrophic corporal mucosa are seen more frequently in cases of GCTs with ECH, compared to those in ECH alone. Gastrin-positive cells in the corporal IM may stimulate enterochromaffin-like (ECL) cells, which may induce hyperplasia, dysplasia or neoplasia by augmenting the effects of hypergastrinemia through a paracrine mechanism on local gastrin-sensitive cells.

Benign gastric polyps: morphological and functional origin

The most common types of benign gastric polyps are fundic gland polyps, hyperplastic polyps, and adenomas. The aim of this study was to determine on which morphological and functional background benign gastric polyps develop. The study includes 85 consecutive patients with gastric polyps and sex- and age-matched controls without polyps selected at random from a general population sample. The type of polyp was hyperplastic in 52 (61%), fundic gland in 18 (21%), adenoma in 10 (12%), carcinoid in 2 (2%), hamartoma in 2 (2%), and inflammatory fibroid in 1 (1%) of the cases. Routine biopsies from the gastric corpus and antrum were examined for presence of gastritis and H. pylori. Blood samples were analyzed for H. pylori antibodies, H+,K+-ATPase antibodies, gastrin, and pepsinogen I. Patients with hyperplastic polyps had increased P-gastrin concentrations and S-H+,K+-ATPase antibody titers and decreased S-pepsinogen I concentrations with a high prevalence of atrophic corpus gastritis or pangastritis. A similar pattern was observed among patients with adenomas, whereas patients with fundic gland polyps had normal serology and a lower prevalence of gastritis and H. pylori infection than controls. In conclusion, hyperplastic polyps and adenomas are generally associated with atrophic gastritis. Patients with fundic gland polyps seem to have a sounder mucosa than controls. Whereas the risk of malignant gastric neoplasia is increased in patients with hyperplastic polyps or adenomas, this does not seem to be the case in patients with fundic gland polyps.

Gastric carcinoids in a patient with pernicious anemia and familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is associated with upper gastrointestinal adenomas and adenocarcinomas. A carcinoid tumor in the base of a duodenal adenoma in a patient with FAP was documented only once before. We report a patient with FAP who has multiple gastric carcinoids plus pernicious anemia as a coexisting disease. Genetic analysis and studies of other FAP patients are necessary to establish whether an association exists between FAP and carcinoid tumors. Optimal management of this type of gastric carcinoid is uncertain.

Progression of gastric enterochromaffin-like cells growth in Zollinger-Ellison syndrome and atrophic body gastritis patients

BACKGROUND

Enterochromaffin-like cell hyperplasia of the gastric body mucosa occurs in hypergastrinaemic conditions such as atrophic body gastritis and Zollinger-Ellison syndrome. However, the time course of change or factors involved are not known.

AIMS

To compare the rate of change of enterochromaffin-like cell proliferation in patients with atrophic body gastritis and Zollinger-Ellison syndrome.

PATIENTS

From a consecutive series of atrophic body gastritis and Zollinger-Ellison syndrome patients, studied at the time of first diagnosis, 10 atrophic body gastritis (4 with pernicious anaemia) and 14 Zollinger-Ellison syndrome (4 with multiple endocrine neoplasia type 1) patients were followed-up for a median time of 48 months.

METHODS

At entry and during follow-up patients underwent: plasma gastrin determination, endoscopic sampling of body mucosa for qualitative assessment of enterochromaffin-like cell hyperplasia pattern and degree of glandular atrophy, qualitative and morphometric analyses of body mucosa endocrine cells.

RESULTS

At time of diagnosis, enterochromaffin-like cell lesions were more severe in atrophic body gastritis than in Zollinger-Ellison syndrome. During follow-up, no significant variations were observed in gastrin values, enterochromaffin-like cell patterns and grade of body mucosa atrophy in atrophic body gastritis. In contrast, gastrin levels were significantly increased [median 1200 (235-2625) vs 1947 (225-5200) pg/ml; p<0.001)] as was total volume density of enterochromaffin-like cells [median 1.60 (0.53-4.06) vs 3.18 (1.35-21.13)% of mucosal epithelial component; (p<0.005)] in Zollinger-Ellison syndrome. Micronodular hyperplasia of enterochromaffin-like cells, present in only one patient at diagnosis, was observed in 8 Zollinger-Ellison syndrome patients at follow-up.

CONCLUSIONS

These data suggest that the progression of enterochromaffin-like cell growth in human gastric mucosa requires an increase of and/or a prolonged exposure to severe hypergastrinaemia.

Atrophic body gastritis patients with enterochromaffin-like cell dysplasia are at increased risk for the development of type I gastric carcinoid

BACKGROUND/AIMS

In the presence of atrophic body gastritis, gastric carcinoid develops from gastric-body mucosa enterochromaffin-like cells. Few data exist on the prevalence of enterochromaffin-like dysplastic lesions in atrophic body gastritis patients and their presumed risk of evolution to carcinoid has never been assessed prospectively in humans. The aim of the present study was to investigate the prevalence and incidence of dysplastic and neoplastic enterochromaffin-like cell lesions in a consecutive series of patients with atrophic body gastritis.

METHODS

A total of 130 atrophic body gastritis patients at diagnosis and 96 atrophic body gastritis patients at follow-up (median 30 months) underwent gastroscopy with multiple biopsies and fasting gastrinaemia evaluation. In patients with enterochromaffin-like cell dysplasia, a more detailed bioptic sampling at follow-up was performed.

RESULTS

Of the 130 atrophic body gastritis patients, only one (0.7%) had a gastric carcinoid polyp, whereas enterochromaffin-like cell dysplasia was found in five patients (3.8%). At follow-up only one out of the 96 atrophic body gastritis patients (1%) was diagnosed as having a carcinoid polyp at 41 months. Enterochromaffin-like cell dysplasia was present in four additional patients (4.2%). Two atrophic body gastritis pernicious anaemia patients with enterochromaffin-like cell dysplasia developed a gastric carcinoid in the follow-up. Among nine atrophic body gastritis patients with enterochromaffin-like cell dysplasia, the incidence of carcinoid tumour was 22% compared to 1.1% of atrophic body gastritis patients without dysplasia (odds ratio: 26.00; 95% confidence interval: 2.089-323.52). During the follow-up, fasting gastrin levels increased significantly only in atrophic body gastritis patients with enterochromaffin-like cell dysplasia (mean 677.4 +/- 66.1 vs 1112.2 +/- 185.6; P = 0.0287).

CONCLUSION

This study provides the first clinical evidence that, in hypergastrinaemic atrophic body gastritis patients, enterochromaffin-like cell dysplasia carries a markedly increased risk for development of type I gastric carcinoid. This suggests that a more detailed endoscopic/bioptic procedure in this subgroup of atrophic body gastritis patients is able to detect gastric carcinoid at an early stage.

Review article: current perspectives on hypergastrinaemia and enterochromaffin-like-cell hyperplasia

Rabeprazole, a new benzimidazole proton pump inhibitor (PPI), is among a class of agents known to be very potent inhibitors of gastric acid secretion. PPIs inhibit hydrogen-potassium adenosine triphosphatase activity on the luminal surface of the parietal cell, effectively blocking the final common pathway for gastric acid secretion. Raising gastric pH stimulates the production of gastrin by G cells in the antrum of the stomach, which can lead to enterochromaffin-like (ECL)-cell hyperplasia. In the past, these changes have been viewed with concern, particularly in the light of studies in rats indicating that hypergastrinaemia and ECL-cell hyperplasia induce gastric carcinoid tumour formation. All available clinical data indicate that long-term PPI use does not lead to carcinoid tumour formation in humans. In fact, both serum gastrin elevation and ECL-cell hyperplasia are now generally viewed as normal physiological responses to gastric acid suppression. Serum gastrin concentrations, in particular, correlate well with gastric acid suppression, which has led to the use of gastrin response by some investigators as a surrogate marker of antisecretory effectiveness. Long-term tolerability data indicate that PPIs have a favourable side-effect profile. Data obtained from patients receiving acute or long-term maintenance rabeprazole therapy support this conclusion. Furthermore, neither animal nor human data obtained with rabeprazole suggest a significant risk for neoplastic changes secondary to hypergastrinaemia.

Hyperplasia of gastric antral beta-microseminoprotein endocrine-like cells and increased serum levels of beta-microseminoprotein in atrophic corpus gastritis

BACKGROUND

Beta-microseminoprotein is a 94-kDa protein present on most mucosal surfaces in the body. It is produced in mucin cells but is also found in a particular type of cells (E-cells) in the gastric antral mucosa. Most of these cells also contain gastrin. In atrophic corpus gastritis the gastrin-producing cells become hyperplastic, and the patients have hypergastrinemia. We wanted to ascertain whether there is a similar effect on the E-cells and on the concentration of beta-microseminoprotein in serum.

METHODS

Antral biopsy specimens from 10 patients with atrophic corpus gastritis and 10 controls were stained immunohistochemically for beta-microseminoprotein and gastrin. beta-Microseminoprotein and gastrin were measured by radioimmunoassay in serum from 15 women with atrophic corpus gastritis and 31 healthy female blood donors.

RESULTS

There was a 3.5-fold increase of the number of E-cells (which also were hypertrophic) and a 2.1 times higher serum concentration of beta-microseminoprotein in the patients with atrophic corpus gastritis than in the control subjects. Gastrin was seen in 28% of the E-cells in patients with atrophic corpus gastritis, compared with 87% in normal antral mucosa. There was no correlation between the serum concentrations of beta-microseminoprotein and gastrin.

CONCLUSIONS

In atrophic corpus gastritis antrum E-cells undergo hyperplasia and hypertrophy, and the proportion of E-cells containing gastrin decreases. Increased amounts of beta-microseminoprotein are secreted to the blood but uncorrelated with gastrin.

Gastric carcinoid expresses the gastrin autocrine pathway

BACKGROUND

In gastric adenocarcinoma the gastrin autocrine-paracrine pathway is activated. As enterochromaffin-like (ECL) cells originate from the same stem as epithelial cells, the aim of this study was to determine if the gastrin autocrine pathway is present in gastric carcinoid.

METHODS

Samples from ten patients with gastric carcinoid were assessed by immunocytochemistry using primary antibodies directed against gastrin precursors and the gastrin/cholecystokinin B receptor and detected using the avidin-biotin immunoperoxidase system.

RESULTS

A high level of expression of precursor and mature gastrin peptides, together with the gastrin receptor, was seen in all carcinoids screened.

CONCLUSION

In common with the glandular epithelium of the stomach the gastrin gene is activated during the neoplastic process in ECL cells. This finding may explain why some carcinoids do not regress after surgical procedures that lower serum gastrin. Antigastrin agents may be a useful treatment for carcinoid either in their own right or as an adjunct to surgery.

Primary biliary cirrhosis and gastric carcinoid: a rare association?

Primary biliary cirrhosis (PBC) is frequently associated with other autoimmune disorders. Although antibodies against gastric parietal cells are found in nearly all PBC patients, autoimmune gastritis is only very rarely associated. We describe a woman with PBC in whom chronic autoimmune gastritis complicated by a large pedunculated gastric carcinoid tumor was found. Additionally, the patient had autoimmune thyroiditis. This was interpreted as the rare association of PBC with Schmidt's syndrome type III. The carcinoid tumor was removed endoscopically. We conclude from the case that an endoscopic screening for autoimmune gastritis should at least be performed in patients with PBC and autoimmune thyroiditis, keeping in mind the possible occurrence of a polyendocrinopathy and the potentially serious complication of a gastric carcinoid tumor.

Basal chromogranin A and gastrin concentrations in circulation correlate to endocrine cell proliferation in type-A gastritis

BACKGROUND

It is not known whether plasma chromogranin analysis could be a complement to histology for detection and grading of gastric fundic mucosal endocrine cell proliferation in hypergastrinemic (type-A) atrophic gastritis.

METHODS

Gastric biopsy sections (body and antrum) from 43 patients with type-A gastritis (9 with gastric carcinoid) were examined for density and micronodules of argyrophil endocrine cells. Fasting blood samples were analyzed for chromogranin A and B, gastrin, and somatostatin.

RESULTS

All patients with carcinoid and 17 of the 34 without carcinoid had micronodules in the gastric fundic mucosa. The median plasma chromogranin A concentration was 5.7 (3.5-40.0) nmol/l in patients with carcinoid, 4.5 (3.0-9.5) nmol/l in patients with micronodules, and 3.7 (0.8-6.0) nmol/l in patients without micronodules. Overall, chromogranin A concentrations correlated to endocrine cell densities in the fundic mucosa (r = 0.64, P < 0.001) and to gastrin concentrations (r = 0.71, P < 0.001). Plasma somatostatin and chromogranin B concentrations did not differ significantly between the groups.

CONCLUSION

In type-A gastritis, analysis of plasma chromogranin A may be a useful complement to histology in estimating the endocrine cell mass. Moreover, subclinical type-A gastritis may be a source of error when chromogranin A analysis is used in the search for neuroendocrine neoplasia.

Gastrointestinal carcinoids--aspects of diagnosis and classification

Gastrointestinal carcinoids are a heterogeneous group of hormone-producing tumours originating from the diffuse neuroendocrine system of the gastrointestinal mucosa. Recent studies have shown that carcinoid tumours share many of the morphological, biochemical and functional properties of the neuroendocrine cells from which they are derived. Identification of these properties, e.g. specific hormone production, contents of secretory granules or specific proteins of the secretory granules/ vesicles, forms the basis for the diagnosis of carcinoid tumours. Classification of gastrointestinal carcinoids is based on the clinical settings under which the tumours develop, tumour site, as well as the morphological and biochemical characteristics of the tumour. Although generally considered a low grade malignancy, carcinoid tumours show a highly variable clinical course from benign tumours discovered incidentally to highly malignant tumours presenting with disseminated spread and disabling hormonal symptoms. Precise knowledge of tumour location, size and stage, as well as growth pattern and hormonal syndromes, is necessary to predict the behaviour of the tumour and optimise treatment.

Involvement of BCL-2 oncoprotein in the development of enterochromaffin-like cell gastric carcinoids

To evaluate the involvement of the apoptosis-suppressing protein BCL-2 in the gastrin-dependent mechanism of induction of gastric enterochromaffin-like (ECL) cell carcinoids, the endocrine cell of the oxyntic mucosa were immunohistochemically investigated in (a) 10 normogastrinemic subjects with histologically normal gastric mucosa; (b) 22 patients with endocrine cell hyperplasia and affected by hypergastrinemic conditions with different risk of gastric carcinoid development, such as sporadic Zollinger-Ellison syndrome (sZES; n = 9), ZES associated with multiple endocrine neoplasia-1 (MEN-1; n = 4), and atrophic fundal gastritis (AFG; n = 9); (c) 14 patients with ECL gastric carcinoids accounting for a total of 31 tumors investigated. In the normal oxyntic mucosa, BCL-2 was consistently expressed by a subset of endocrine cells accounting for 50.0% (median; range, 24.6-74.0%) of the total number of endocrine cells immunostained for chromogranin A (CgA) in consecutive sections. BCL-2 immunoreactive cells were located mostly in the middle mucosal layer, suggesting a role for the protein during downward migration of maturing endocrine cells. No BCL-2 immunoreactivity was found in other specialized gastric epithelial cells. Expression of BCL-2 by hyperplastic oxyntic endocrine cells (mostly ECL cells) varied in parallel with the risk of carcinoid development. In fact, the ratio of BCL-2- to CgA-immunoreactive cells was reduced (median, 4.6%; p less than 0.0001; range, 0.9-42.0%) in sZES, a condition showing virtually no risk, unchanged (median, 55.6%; range 29.4-83.8 %) in cases of MEN-1/ZES with intermediate risk, and increased (median 87.6%; p less than 0.014; range, 48.8-199.4%) in cases of AFG, a condition at the highest risk of carcinoid. In ECL cell carcinoids, BCL-2 expression varied markedly from one tumor to another even in the same patient and was low or absent in most cases. In both hyperplastic and neoplastic ECL cells, an inverse relation between BCL-2 expression and CgA immunoreactivity, that is, the cell granule content, was found. These results suggest that BCL-2 expression by hyperplastic ECL cells is independent of the influence of serum gastrin and may contribute to the development of ECL cell carcinoid tumors by extending cell exposure to oncogenic factors. Once a carcinoid tumor is established, BCL-2 expression becomes inconsistent.

Carcinoid tumors in Denmark 1978-1989 and the risk of subsequent cancers. A population-based study

BACKGROUND

Previous studies have suggested an excess cancer risk in patients with carcinoid tumors. This association was reexamined using truly population-based data.

METHODS

By means of data from the Danish Cancer Registry all carcinoid tumors diagnosed in Denmark between 1978 and 1989 were identified. All patients with primary carcinoid tumors were studied for the occurrence of subsequent cancers. The numbers of subsequent cancers observed in the follow-up period were compared with the expected numbers calculated from population rates.

RESULTS

A total of 1029 patients with carcinoid tumors were identified (464 men and 565 women). The annual age-adjusted incidence rates (world standardized) for carcinoid tumors during 1978-1989 were stable at about 1.1 per 100,000 person-years for both men and women. The patients were followed for the occurrence of subsequent cancers over a period comprising 2512 person-years. Thirty subsequent cancers were identified in 29 patients. The overall relative risk of subsequent cancers was 1.1 (95% CI, 0.8-1.6). Subsequent cancers of the thyroid were in excess (RR, 21.4; 95% CI, 2.4-77.1; n = 2), as were tumors of the brain and nervous system (RR, 5.4; 95% CI, 1.1-15.9; n = 3) and non-Hodgkin's lymphomas (RR, 5.8; 95% CI, 1.2-16.9; n = 3).

CONCLUSIONS

Overall, this population-based study does not support previous studies of an excess cancer risk in patients with carcinoid tumors. Increased risks of cancers of the thyroid, tumors of the brain and nervous system, and non-Hodgkin's lymphomas were observed, but these findings were based on few cases.

Endocrine tumours of the stomach

This review illustrates the current classification of gastric endocrine tumors: a) carcinoid tumors (associated with chromic atrophic gastritis; with Zollinger-Ellison syndrome and multiple endocrine neoplasia type I; sporadic) and b) neuroendocrine carcinomas. The pathogenetic characteristics and clinical implications that justify this classification are discussed.

Genotoxicity, carcinogenicity and acid-suppressing medications

With the availability of increasingly potent acid-suppressing medications, questions continue to rise concerning the safety of these compounds in regards to carcinogenetic potential. In this review, we examine current concepts and procedures relating to genotoxicity, the potential for a chemical agent to interact with and alter the genomic information of the cell, and carcinogenesis. A description and discussion of commonly utilized techniques for the determination of (a) in vitro mutagenicity, (b) in vitro and in vivo DNA damage and repair, (c) in vitro and in vivo chromosomal damage and (d) chronically dosed animal tumorigenesis development is presented. Observations from these procedures as they have been applied to a review of the safety of acid-suppressing medications will be discussed. An evaluation of reports relating to potential genotoxic and carcinogenic hazards of therapeutically relevant acid-suppressing medications (cimetidine, ranitidine, omeprazole) is presented. Information related to the effect of prolonged administration of acid-suppressing medications, alterations of serum gastrin levels, and the potential for tumor promotion is discussed.

Effects of acid suppression on microbial flora of upper gut

Decreased acid secretion, due to therapy or disease, predisposes to increased bacterial counts in gastric juice. As bacterial numbers increase, the number of nitrate-reducing strains and the concentration of luminal nitrite usually also increase. However, there is controversy (mainly because of assay problems) about whether decreased acid increases generation of N-nitroso compounds: these may be produced by acid or by bacterial catalysis, and the relative contributions of each are still uncertain. Other potentially important factors include ascorbate secretion (can prevent nitrite conversion to nitroso compounds) and the particular spectrum of nitroso compounds produced. Nitrosation of several histamine H2-receptor antagonists has been demonstrated experimentally, but under conditions that are very unlikely to be encountered clinically. Some acid suppressant therapies have been claimed to aid eradication of Helicobacter pylori, but more work is needed to evaluate this. If ulcer treatment regimens do not also address eradication of H. pylori (when present), gastritis will progress, and the recently documented association between H. pylori and gastric carcinoma needs to be considered. Enteric flora probably also increase if acid secretion is markedly reduced: this does not appear to have nutritional consequences but probably reduces the resistance to occasional infections, of which cholera is the best documented.

Effects of hypochlorhydria and hypergastrinemia on structure and function of gastrointestinal cells. A review and analysis

Since hypochlorhydria can induce hypergastrinemia, and gastrin has a trophic effect on some gastrointestinal cells, states that cause elevated plasma gastrin levels are of interest in terms of effects on cell growth and function. This article reviews the relationship between gastric mucosal cells during periods of acid stimulation and inhibition and analyses the effects of hypochlorhydria and hypergastrinemia on gastric and colonic cells and tumors. Hypochlorhydria releases the inhibitory effect of antral gastrin cells, inducing them to release gastrin in the presence of peptides or amino acids in the gastric lumen or in response to antral distension. Gastrin stimulates the oxyntic mucosa, which may lead to hyperplasia of enterochromaffin-like cells, resulting in enterochromaffin-like carcinoid tumors in aged rats and, rarely, in patients with chronic atrophic gastritis or gastrinomas. In addition to hypergastrinemia, other factors appear to be required for the progression of enterochromaffin-like hyperplasia to carcinoids; genetic factors may be involved. Gastrin elevations due to antisecretory drug therapy are indirectly proportional to the degree of acid inhibition and are reversible upon cessation of therapy. The gastrin levels during omeprazole therapy are similar to those caused by gastric vagotomy. Available evidence does not support a relationship between hypergastrinemia and the occurrence or growth of gastric carcinoma or colonic tumors.

Hyperplastic manifestations of enterochromaffin-like cells in the stomach of rats with congenital moderate hypergastrinemia

The effect of moderate congenital hypergastrinemia on the enterochromaffin-like (ECL) cells was investigated in Zucker rats 4 and 18 months of age by combining autoradiography after tritiated thymidine injection and selective immunocytochemistry. In both age groups the serum gastrin concentration was 200% higher in obese (fa/fa) than in lean (Fa/Fa; Fa/fa) littermates. In 4-month-old obese rats there was a 120% increase (p < 0.05) in the ECL cell labeling index and also a moderate increase in the ECL cell density (p < 0.05) compared with lean controls. In 18-month-old obese rats the hyperplasia was quantitatively more prominent, with both linear and micronodular ECL cell hyperplasia. At this stage, the ECL cell labeling indices in obese and in lean animals were similar. These data support the hypothesis that moderate hypergastrinemia initially accelerates the ECL cell proliferation rate, leading to diffuse ECL cell hyperplasia. In similar conditions, at the latter stage, linear and micronodular ECL cell hyperplasia also develop in most of the hypergastrinemic animals.

Other gastrointestinal polyps

Gastrointestinal polyp is a descriptive concept--observation of an elevated broad-based or stalked lesion which can be defined exactly only when examined histologically. Therefore, all polyps must, in principle, be snared or excised to achieve a final diagnosis. Nonneoplastic polyps or tumor-like lesions were formerly considered innocent findings with no malignant potential, while neoplastic adenomas with dysplasia are well-known premalignant lesions. This view of the totally harmless nature of nonneoplastic polyps is no longer true. At least the dominantly inherited juvenile polyposis and Peutz-Jeghers polyposis syndromes definitely have malignant potential through adenomatous change in the originally hamartomatous lesions. Consequently, juvenile polyposis is best treated with colectomy and ileorectal anastomosis, and repeated multiple polypectomies are now recommended in Peutz-Jeghers polyposis, in combination with laparotomy when feasible. In addition, hyperplastic gastric polyps may reflect an underlying atrophic gastritis implying increased risk of gastric carcinoid tumors and cancer. Furthermore, even colorectal hyperplastic polyps may undergo adenomatous change, and thus represent, theoretically, a reservoir from which adenomas arise.

Gastrin-histamine interactions: direct and paracrine elements

The receptors mediating the physiologic actions of gastrin on acid secretion and growth have thus far not been localized to specific cells or fully characterized. Studies in canine fundic mucosa indicate that gastrin receptors are present on several cell types, including parietal cells and somatostatin cells. There is also increasing evidence for a gastrin-inducible pool of histamine in the fundic mucosa which is presumably stored in histamine-enterochromaffin-like cells. From the vantage point of studies in the canine fundic mucosa, the issue is no longer which cell type has the gastrin receptor but to sort out the mechanisms by which the effects of the gastrin receptors on endocrine/paracrine (histamine and somatostatin) cells and exocrine (parietal) cells are integrated to regulate secretory function and mucosal growth and differentiation.