Signet ring cells in gastric carcinomas are derived from neuroendocrine cells

Impact of Alcian blue and periodic acid Schiff expression on the prognosis of gastric signet ring cell carcinoma

BACKGROUND

The Alcian blue (AB) and periodic acid Schiff (PAS) stains are representative mucus markers in gastric signet ring cell carcinoma (SRCC). They are low-cost special staining methods used to detect acidic mucus and neutral mucus, respectively. However, the clinical importance of the special combined AB and PAS stain is unclear.

AIM

To investigate AB expression, PAS expression and the AB-to-PAS (A/P) ratio in gastric SRCC patients and to assess patient prognosis.

METHODS

Paraffin-embedded sections from 83 patients with gastric SRCC were stained with AB and PAS, and signet ring cell positivity was assessed quantitatively. Immunohistochemical staining for Ki67, protein 53 (P53) and human epidermal growth factor receptor 2 (HER2) was performed simultaneously. The cancer-specific survival (CSS) rate was estimated via Kaplan-Meier analysis. Cox proportional hazards models were used for univariate and multivariate survival analyses.

RESULTS

Kaplan-Meier survival analysis revealed that the 3-year CSS rate was significantly greater in the high-PAS-expression subgroup than in the low-PAS-expression subgroup (P < 0.001). The 3-year CSS rate in the A/P ≤ 0.5 group was significantly greater than that in the A/P > 0.5 group (P = 0.042). Univariate Cox regression analysis revealed that the factors affecting prognosis included tumor diameter, lymph node metastasis, vessel carcinoma embolus, tumor stage, the A/P ratio and the expression of Ki67, P53 and the PAS. Cox multivariate regression analysis confirmed that low PAS expression [hazard ratio (HR) = 3.809, 95% confidence interval (CI): 1.563-9.283, P = 0.003] and large tumor diameter (HR = 2.761, 95%CI: 1.086-7.020, P = 0.033) were independent risk factors for poor prognosis.

CONCLUSION

A/P > 0.5 is potentially a risk factor for prognosis, and low PAS expression is an independent risk factor in the prognosis of gastric SRCC. PAS expression and the A/P ratio could help in predicting the clinical prognosis of patients with SRCC.

Inflammation and Digestive Cancer

Chronic inflammation is linked to carcinogenesis, particularly in the digestive organs, i.e., the stomach, colon, and liver. The mechanism of this effect has, however, only partly been focused on. In this review, we focus on different forms of chronic hepatitis, chronic inflammatory bowel disease, and chronic gastritis, conditions predisposing individuals to the development of malignancy. Chronic inflammation may cause malignancy because (1) the cause of the chronic inflammation is itself genotoxic, (2) substances released from the inflammatory cells may be genotoxic, (3) the cell death induced by the inflammation induces a compensatory increase in proliferation with an inherent risk of mutation, (4) changes in cell composition due to inflammation may modify function, resulting in hormonal disturbances affecting cellular proliferation. The present review focuses on chronic gastritis (Helicobacter pylori or autoimmune type) since all four mechanisms may be relevant to this condition. Genotoxicity due to the hepatitis B virus is an important factor in hepatocellular cancer and viral infection can similarly be central in the etiology and malignancy of inflammatory bowel diseases. Helicobacter pylori (H. pylori) is the dominating cause of chronic gastritis and has not been shown to be genotoxic, so its carcinogenic effect is most probably due to the induction of atrophic oxyntic gastritis leading to hypergastrinemia.

Endoscopic and clinicopathologic features of early gastric signet ring cell carcinoma ≤20 mm: a retrospective observational study

OBJECTIVES

Limited literature exists on the characteristics of early gastric signet ring cell carcinoma (GSRCC) within 20 mm. This study aimed to explore this type of cancer from several aspects, to provide guidance for early detection and intervention of GSRCC.

METHODS

We retrospectively collected data from 24 patients diagnosed with early GSRCC ≤20 mm in Beijing Friendship Hospital from 2016 to 2021. According to tumor size, those lesions were divided into three groups: diminutive group (1-5 mm, n = 4), small group (6-10 mm, n = 12) and intermediate group (11-20 mm, n = 8). The clinicopathologic and endoscopic characteristics of GSRCC were compared among the three groups.

RESULTS

Treatment strategies for lesions differed according to the size (p<.05). There were no significant differences among the three groups with regard to age, sex, Helicobacter pylori infection, tumor location and macroscopic type. Lesions were often flat type and more likely to present with discoloration, uneven color, ulceration and submucosal invasion with the increase of diameter. Almost all cases showed abnormal intervening part (IP) under magnifying endoscopy.

CONCLUSIONS

The location of early signet ring cell carcinoma is not specific, and the diminutive lesions are often flat. Abnormal IP may be the early endoscopic feature of early GSRCC.

Synaptophysin and chromogranin A expression analysis in human tumors

The expression of the neuroendocrine markers synaptophysin and chromogranin A was analyzed by immunohistochemistry in 14,584 samples from 103 different tumor types and subtypes in a tissue microarray format. At least one of these markers was found to be positive in 96.7% of tumors from various subtypes of neuroendocrine neoplasms. In non-neuroendocrine tumors, synaptophysin and/or chromogranin A staining was seen in 6.3% (n = 584), specifically in 41 of 88 non-neuroendocrine tumor entities. Basal cell carcinomas of the skin (50% positive for chromogranin A alone) and adrenocortical carcinomas (91.7% positive for synaptophysin alone) stood out due to a frequent expression of only one specific marker. A subdivision of non-neuroendocrine neoplasms revealed "neuroendocrine differentiation" most commonly in adenocarcinomas from the female genital tract (18.9%), from pancreatico-/hepato-/biliary tract (15.8%) and the prostate (14.9%) while it was rare in urothelial (1.0%) and squamous cell carcinomas (0.6%). A comparison with clinico-pathological parameters of tumor aggressiveness did not suggest a clinical significance of neuroendocrine marker expression in 204 endometrium cancers, 249 pancreatic adenocarcinomas, 233 gastric adenocarcinomas and 1,182 colorectal adenocarcinomas. Within a cohort of 1,073 breast cancers of no special type, synaptophysin positivity was seen in 4.9% of cases and it was significantly linked to advanced tumor stage (p = 0.0427), high tumor grade (p = 0.0319) and loss of estrogen receptor expression (p = 0.0061) but unrelated to patient outcome. In conclusion, "neuroendocrine differentiation" can be observed in many different tumor types with non-neuroendocrine morphology. Evidence for a statistically significant association (p < 0.0001) between such a "neuroendocrine differentiation" and tumor aggressiveness could not be found.

Characterization of giant neuroendocrine cells in the pregnant New Zealand white rabbit vagina demonstrated by histological, histochemical, and immunohistochemical methods

The vagina is part of the genitalia and constitutes part of the birth canal. Sperm is deposited into vagina, and it acts in transport of sperm. Pregnancy is a complex process involving different physiological changes in the body associated with hormonal and metabolic alterations that control maternal and fetal demands. During pregnancy, neuroendocrine cells in rabbit vagina are considered part of the diffuse neuroendocrine system observed throughout the body. Giant neuroendocrine cells in rabbit vagina during pregnancy have not been observed previously. This study detected the presence of giant neuroendocrine cells in the vagina of the pregnant rabbit. The presence of these cells was demonstrated with the use of different histological techniques, including hematoxylin and eosin, PAS, combined Alcian blue-PAS, Crossmon's trichrome, and the Grimelius silver method. Giant neuroendocrine cells were observed in late-pregnancy intraepithelial sites and on the lamina propria. These cells were characterized by vacuolated basophilic cytoplasm with PAS- and PAS-AB-positive granules. Moreover, neuroendocrine cells exhibited an argyrophilic character. Immunohistochemically, neuroendocrine cells in rabbit vagina during pregnancy demonstrated positive immunoreactivity to neuron-specific enolase (NSE) with different intensities, mild immunoreactivity to the vascular endothelial growth factor (VEGF), and negative immunoreactivity to CD68.

Mixed large and small cell neuroendocrine carcinoma of the stomach: A case report and review of literature

BACKGROUND

Gastric neuroendocrine carcinoma (GNEC) is a rare histological subtype of gastric cancer, which is categorized into small cell and large cell neuroendocrine carcinomas. It is characterized by strong invasiveness and poor prognosis. Mixed large and small cell neuroendocrine carcinoma (L/SCNEC) is an extremely rare pathological type of gastric cancer, and there have been no reports on this situation until now.

CASE SUMMARY

Herein, we first present a 57-year-old patient diagnosed with L/SCNEC of the stomach. A 57-year-old Chinese male presented with epigastric discomfort. Outpatient gastroscopic biopsy was performed, and pathological examination revealed that the cardia was invaded by adenocarcinoma. The patient underwent laparoscopic-assisted radical proximal subtotal gastrectomy and was diagnosed with L/SCNEC. He refused adjuvant treatment and was followed up every 3 mo. Eight months after the operation, the patient showed no evidence of local recurrence or distant metastasis.

CONCLUSION

We advocate conducting further genomic studies to explore the origin of gastric large cell and small cell neuroendocrine carcinoma and using different chemotherapy schemes according to large or small cell neuroendocrine carcinoma of the stomach for clinical research to clarify the heterogeneity of GNEC and improve the prognosis of patients with GNEC.

Do Gastric Signet Ring Cell Carcinomas and ECL-Cell Neuroendocrine Tumours Have a Common Origin?

Gastric cancer is a heterogenous group of tumours, and a better understanding of the carcinogenesis and cellular origin of the various sub-types could affect prevention and future treatment. Gastric neuroendocrine tumours (NETs) and adenocarcinomas that develop in the gastric corpus and fundus of patients with chronic atrophic gastritis have atrophic gastritis, hypoacidity, and hypergastrinemia as common risk factors and a shared cellular origin has been suggested. In particular, signet ring cell carcinomas have previously been suggested to be of neuroendocrine origin. We present a case of a combined gastric NET and signet ring cell carcinoma in a patient with hypergastrinemia due to autoimmune chronic atrophic gastritis. The occurrence of such a combined tumour strengthens the evidence that gastric NETs and signet ring cell carcinomas develop from a common origin.

The dawn of precision medicine in diffuse-type gastric cancer

Gastric cancer (GC) is one of the most common malignancies worldwide. The histology- and morphology-based Lauren classification of GC has been widely used for over 50 years in clinical practice. The Lauren classification divides GC into intestinal and diffuse types, which have distinct etiology, molecular profiles, and clinicopathological features. Diffuse-type GC (DGC) accounts for approximately 30% of GCs. Tumor cells lack adhesion and infiltrate the stroma as single cells or small subgroups, leading to easy dissemination in the abdominal cavity. Clinically, DGC has aggressive traits with a high risk of recurrence and metastasis, which results in unfavorable prognosis. Although systemic chemotherapy is the main therapeutic approach for recurrent or metastatic GC patients, clinical benefits are limited for patients with DGC. Therefore, it is urgent to develop effective therapeutic strategies for DGC patients. Considerable research studies have characterized the molecular and genomic landscape of DGC, of which tight junction protein claudin-18 isoform 2 (CLDN18.2) and fibroblast growing factors receptor-2 isoform IIIb (FGFR2-IIIb) are the most attractive targets because of their close association with DGC. Recently, the impressive results of two phase II FAST and FIGHT trials demonstrate proof-of-concept, suggesting that anti-CLDN18.2 antibody (zolbetuximab) and FGFR2-IIIb antibody (bemarituzumab) are promising approaches for patients with CLDN18.2-positive and FGFR2-IIIb-positive GC, respectively. In this review, we summarize the clinicopathological features and molecular profiles of DGC and highlight a potential therapeutic target based on the findings of pivotal clinical trials.

Time to Classify Tumours of the Stomach and the Kidneys According to Cell of Origin

Malignant tumours are traditionally classified according to their organ of origin and whether they are of epithelial (carcinomas) or mesenchymal (sarcomas) origin. By histological appearance the site of origin may often be confirmed. Using same treatment for tumours from the same organ is rational only when there is no principal heterogeneity between the tumours of that organ. Organ tumour heterogeneity is typical for the lungs with small cell and non-small cell tumours, for the kidneys where clear cell renal carcinoma (CCRCC) is the dominating type among other subgroups, and in the stomach with adenocarcinomas of intestinal and diffuse types. In addition, a separate type of neuroendocrine tumours (NETs) is found in most organs. Every cell type able to divide may develop into a tumour, and the different subtypes most often reflect different cell origin. In this article the focus is on the cells of origin in tumours arising in the stomach and kidneys and the close relationship between normal neuroendocrine cells and NETs. Furthermore, that the erythropoietin producing cell may be the cell of origin of CCRCC (a cancer with many similarities to NETs), and that gastric carcinomas of diffuse type may originate from the ECL cell, whereas the endodermal stem cell most probably gives rise to cancers of intestinal type.

Proton Pump Inhibitors and Gastric Cancer

Concerns have been raised regarding the long-term use of proton pump inhibitors (PPIs) as an important risk factor for gastric cancer in clinical practice. PPIs can cause hypergastrinemia at clinical doses, and hypergastrinemia has been reported to induce malignant neoplasms in the stomach in previous animal studies. In humans, the proliferation of enterochromaffin-like (ECL) cells induced by hypergastrinemia is suspected as a potential mechanism of gastric cancer. Meanwhile, persistent Helicobacter pylori (H. pylori) infection causes gastric atrophic change, which itself is a major cause of gastric cancer, and it can further increase the risk of gastric cancer by strengthening corpus atrophy through interaction with PPIs. Recent epidemiologic studies have reported an important link between long-term PPI intake and gastric cancer risk even after successful eradication of H. pylori. However, due to the methodological limitations of observational clinical studies, the causal relationship is still not clear, and a recent big data-based study reported that long-term PPI use was not related to gastric cancer incidence. Taken together, despite the potential detrimental effects of PPIs, it is currently difficult to draw a definite conclusion about its association with gastric cancer. To minimize the possibility of gastric cancer in H. pylori-infected patients or precancerous lesions in long-term PPI users, long-term PPI administration should be limited to the minimum effective dose, and antibacterial treatment for H. pylori should be considered.

Tumor Classification Should Be Based on Biology and Not Consensus: Re-Defining Tumors Based on Biology May Accelerate Progress, An Experience of Gastric Cancer

Simple Summary

Rational treatment of diseases including cancers depends on knowledge of their cause as well as their development. The present review is based upon more than 40 years’ work in clinical gastroenterology, gastric physiology, and pathology. The central role of hormones as well as local endocrine cells in cancer development has become apparent. Moreover, the classification of tumors should focus not only on the organ of origin but also on the cell of origin. All cells with the ability to divide may give rise to tumors. Based upon knowledge of the growth regulation of the cell of origin, prophylaxis and treatment may be tailored. Presently, there is hope for individual treatment of cancer patients based upon genetic analyses of tumors. However, with correct identification of the cell of origin, this may not be necessary.

Abstract

Malignant tumors are a consequence of genetic changes mainly occurring during cell division, sometimes with a congenital component. Therefore, accelerated cell divisions will necessarily predispose individuals, whether due to conditions of chronic cell destruction or hormonal overstimulation. It has been postulated that two genetic hits are necessary for the development of malignancy (Knudson). The correct view is probably that the number of genetic changes needed depends on the role the mutated genes have in proliferation and growth control. Hormones should accordingly be regarded as complete carcinogens. In this review based upon experience of gastric cancer where gastrin is central in the pathogenesis, it is argued that oxyntic atrophy—and not metaplasia as postulated by Correa—is the central precancer change in gastric mucosa. Moreover, the target cell of gastrin, the enterochromaffin-like (ECL) cell, is central in gastric carcinogenesis and most probably the cell of origin of gastric carcinomas of the diffuse type according to Lauren (a classification probable in accordance with biology). The distinction between adenocarcinomas and neuroendocrine carcinomas based upon a certain percentage of cancer cells with neuroendocrine differentiation is questioned. To make progress in the treatment of cancer, a correct classification system and knowledge of the pathogenesis are necessary.

Towards Understanding of Gastric Cancer Based upon Physiological Role of Gastrin and ECL Cells

Simple Summary

Generally, we know that cancers represent genetic changes in tumour cells, but we most often do not know the causes of cancers or how they develop. Our knowledge of the regulation of gastric acid secretion is well known, with the gastric hormone gastrin maintaining gastric acidity by stimulation of the enterochromaffin-like (ECL) cell to release histamine, which subsequently augments acid secretion. Furthermore, it seems to be a general principle that stimulation of function (which, for the ECL cell, is release of histamine) in a parallel way stimulates the proliferation of the same cell. Long-term hyperstimulation of cell division predisposes to genetic changes and, thus, development of tumours. All conditions with reduced gastric acidity result in an increased risk of gastric tumours due to elevated gastrin in order to restore gastric acidity. It is probable that Helicobacter pylori infection (the most important cause of gastric cancer), as well as drugs inhibiting gastric acid secretion induce gastric cancer in the long-term, due to an elevation of gastrin caused by reduced gastric acidity. Gastric carcinomas have been shown to express ECL cell markers, further strengthening this relationship.

Abstract

The stomach is an ideal organ to study because the gastric juice kills most of the swallowed microbes and, thus, creates rather similar milieu among individuals. Combined with a rather easy access to gastric juice, gastric physiology was among the first areas to be studied. During the last century, a rather complete understanding of the regulation of gastric acidity was obtained, establishing the central role of gastrin and the histamine producing enterochromaffin-like (ECL) cell. Similarly, the close connection between regulation of function and proliferation became evident, and, furthermore, that chronic overstimulation of a cell with the ability to proliferate, results in tumour formation. The ECL cell has long been acknowledged to give rise to neuroendocrine tumours (NETs), but not to play any role in carcinogenesis of gastric adenocarcinomas. However, when examining human gastric adenocarcinomas with the best methods presently available (immunohistochemistry with increased sensitivity and in-situ hybridization), it became clear that many of these cancers expressed neuroendocrine markers, suggesting that some of these tumours were of neuroendocrine, and more specifically, ECL cell origin. Thus, the ECL cell and its main regulator, gastrin, are central in human gastric carcinogenesis, which make new possibilities in prevention, prophylaxis, and treatment of this cancer.

Correct Identification of Cell of Origin May Explain Many Aspects of Cancer: The Role of Neuroendocrine Cells as Exemplified from the Stomach

Cancers are believed to originate from stem cells. Previously, the hypothesis was that tumors developed due to dedifferentiation of mature cells. We studied the regulation of gastric acid secretion and showed that gastrin through the gastrin receptor stimulates enterochromaffin-like (ECL) cell histamine release and proliferation. In animal and human studies, we and others showed that long-term hypergastrinemia results in ECL cell-derived tumor through a sequence of hyperplasia, dysplasia, neuroendocrine tumors (NETs), and possibly neuroendocrine carcinomas (NECs) and adenocarcinomas of diffuse type. Perhaps, other cancers may also have their origin in differentiated cells. Knowledge of the growth regulation of the cell of origin is important in cancer prophylaxis and treatment. Physiology plays a central role in carcinogenesis through hormones and other growth factors. Every cell division implies a small risk of mutation; thus mitogens are also mutagens. Moreover, metastasis of slow proliferating cells may also explain so-called tumor dormancy and late recurrence.

Clinical consequences of controversies in gastric physiology

Studies on the regulation of gastric acid secretion started more than 100 years ago at an early phase of experimental physiology. In nearly the whole last century there were disputes about the interpretation of the findings: the interaction between the three principle gastric acid secretagogues acetylcholine, gastrin and histamine, the cell producing the relevant histamine which turned out to be the ECL cell, the ability of the ECL cell to divide and thus develop into tumours, the classification of gastric carcinomas and the mechanism for Helicobacter pylori carcinogenesis. The elucidation of the central role of the ECL cell and thus its main regulator, gastrin, solve all these controversies, and gives a solid base for handling upper gastrointestinal diseases.

Mucin expression in gastric- and gastro-oesophageal signet-ring cell cancer: results from a comprehensive literature review and a large cohort study of Caucasian and Asian gastric cancer

BACKGROUND

The literature on the prognostic relevance of signet-ring cell (SRC) histology in gastric cancer (GC) is controversial which is most likely related to inconsistent SRC classification based on haematoxylin-eosin staining. We hypothesised that mucin stains can consistently identify SRC-GC and predict GC patient outcome.

METHODS

We performed a comprehensive literature review on mucin stains in SRC-GC and characterised the mucin expression in 851 Caucasian GC and 410 Asian GC using Alcian Blue (AB)-Periodic Acid-Schiff (PAS), MUC2 (intestinal-type mucin), and MUC5AC (gastric-type mucin). The relationship between mucin expression and histological phenotype [poorly cohesive (PC) including proportion of SRCs, non-poorly cohesive (non-PC), or mucinous (MC)], clinicopathological variables, and patient outcome was analysed.

RESULTS

Depending on mucin expression and cut-offs, the positivity rates of SRC-GC reported in the literature varied from 6 to 100%. Patients with MUC2 positive SRC-GC or SRC-GC with (gastro)intestinal phenotype had poorest outcome. In our cohort study, PC with ≥ 10% SRCs expressed more frequently MUC2, MUC5AC, and ABPAS (p < 0.001, p = 0.004 and p < 0.001, respectively). Caucasians with AB positive GC or combined ABPAS-MUC2 positive and MUC5AC negative had poorest outcome (all p = 0.002). This association was not seen in Asian patients.

CONCLUSIONS

This is the first study to suggest that mucin stains do not help to differentiate between SRC-GC and non-SRC-GC. However, mucin stains appear to be able to identify GC patients with different outcome. To our surprise, the relationship between outcome and mucin expression seems to differ between Caucasian and Asian GC patients which warrants further investigations.

Primary signet ring cell carcinoma with neuroendocrine differentiation arising in mucinous borderline tumor of the ovary

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Primary signet ring cell carcinoma in ovarian mucinous tumor is rare.

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The most important differential diagnosis is metastatic carcinoma.

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We report a case of primary ovarian signet ring cell carcinoma in mucinous tumor.

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Clinicopathological correlation is essential to establish the correct diagnosis.

Gastric cancer and gastrin: on the interaction of Helicobacter pylori gastritis and acid inhibitory induced hypergastrinemia

Gastric cancer, a disease with a reduced frequency for decades, now appears to be on the rise again in young Americans. The epidemiology of gastric cancer differs between tumors in the cardia and those of the more distal parts of the stomach. The tumors are divided into the intestinal type showing glandular growth pattern and the diffuse type with a different pattern. The latter often expresses neuroendocrine and more specifically ECL-cell markers suggesting that they originate from the ECL cell, the target cell for the antral hormone, gastrin. Helicobacter pylori gastritis is accepted as the major cause of gastric cancer, but only after having induced oxyntic atrophy which reduces gastric acid secretion and thus induces hypoacidity leading to hypergastrinemia. Long-term hypergastrinemia is known to induce malignant neoplasia in the stomach of animals as well as man. Recently treatment with proton pump inhibitor after Helicobacter pylori eradication in patients with gastroesophageal reflux disease, has been reported to predispose to gastric cancer. Since profound acid inhibition is a well-known cause of gastric neoplasia, it is to be expected that Helicobacter pylori infection and profound acid inhibition has an additive or possibly potentiating effect on the development of gastric cancer.

The Enterochromaffin-like [ECL] Cell-Central in Gastric Physiology and Pathology

Background: Studies on the regulation of gastric and pancreatic secretion began more than 100 years ago. Secretin was the first hormone postulated to exist, initiating the field of endocrinology. Gastrin produced in the antral mucosa was the second postulated hormone, and together with histamine and acetylcholine, represent the three major gastric acid secretagogues known since 1920. For a long time, the mast cell was the only recognized histamine-producing cell in the oxyntic mucosa and, in the mid-1980s, the ECL cell was recognized as the cell producing histamine, taking part in the regulation of gastric acid secretion. Methods: This review is based upon literature research and personal knowledge. Results: The ECL cell carries the gastrin receptor, and gastrin regulates its function (histamine release) as well as proliferation. Long-term hypergastrinemia results in gastric neoplasia of variable malignancies, implying that gastric hypoacidity resulting in increased gastrin release will induce gastric neoplasia, including gastric cancer. Conclusions: The trophic effect of gastrin on the ECL cell has implications to the treatment with inhibitors of acid secretion.

Proton pump inhibitor: The dual role in gastric cancer

Proton pump inhibitors (PPIs) are one of the most frequently used medications for upper gastrointestinal diseases. However, a number of physicians have raised concern about the serious side effects of long-term use of PPIs, including the development of gastric cancer. Recent epidemiological studies have reported a significant association between long-term PPI intake and the risk of gastric cancer, even after successful Helicobacter pylori eradication. However, the effects of PPIs on the development of pre-malignant conditions such as atrophic gastritis or intestinal metaplasia are not fully known, suggesting the need for comprehensive and confirmative studies are needed in the future. Meanwhile, several experimental studies have demonstrated the effects of PPIs in reducing chemoresistance in gastric cancer cells by modulating the acidic microenvironment, cancer stemness and signal transducer and activator of transcription 3 (STAT3) signaling pathway. The inhibitory effects of PPIs on STAT3 activity may overcome drug resistance and enhance the efficacy of conventional or targeted chemotherapeutic agents. Taken together, PPIs may “play dual role” in gastric carcinogenesis and treatment of gastric cancer.

The Significant Influence of the Neuroendocrine Component on the Survival of Patients with Gastric Carcinoma Characterized by Coexisting Exocrine and Neuroendocrine Components

Background

Gastric adenocarcinoma patients with a neuroendocrine (NE) component are frequently observed in routine practice. Several previous studies have investigated the influence of a NE component on the survival of these patients; however, the results were inconsistent.

Methods

We retrospectively investigated a consecutive series of 95 gastric adenocarcinoma patients with a NE component and 190 gastric adenocarcinoma patients without a NE component. We adopted 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% as the cut-off proportions of the NE component, respectively, and analyzed the patients' overall survival according to the proportion of the NE component.

Results

The 1-, 3-, and 5-year actual survival rates of the patients with a NE component were 90.1%, 72.3%, and 67.2%, respectively, and for those without a NE component 94.2%, 79.3%, and 75.7%, respectively. The multivariate analysis showed that the patients with NE components >70% (HR: 2.156; 95% CI: 1.011, 4.597; p=0.047) and >90% (HR: 2.476; 95% CI: 1.088, 5.634; p=0.031) had significantly worse survival than those without a NE component. Only the diameter of tumors (>4.64 cm) (HR: 2.585; 95% CI: 1.112, 6.006; p=0.027) and pN3 (HR: 2.953; 95% CI: 1.051, 8.293; p=0.040) were independently associated with worse overall survival for gastric adenocarcinoma patients with a NE component (all p<0.05).

Conclusion

Gastric adenocarcinoma patients with a NE component >70% and >90% have significantly worse survival than those without a NE component. Only the diameter of tumors and the number of metastatic lymph nodes are independent prognostic factors for gastric adenocarcinoma patients with a NE component.

Long-term use of proton-pump inhibitors and risk of gastric cancer: a review of the current evidence

Gastric cancer remains one of the leading cancers in the world with a high mortality, particularly in East Asia. Helicobacter pylori infection accounts for the majority of the noncardia gastric cancers by triggering gastric inflammation and subsequent neoplastic progression. Eradication of H. pylori can reduce, but not totally eliminate, subsequent risk of developing gastric cancer. Proton-pump inhibitors (PPIs) are one of the most widely prescribed medications worldwide. With their profound gastric-acid suppression, there are concerns about a possible carcinogenic role in gastric cancer, due to induced hypergastrinemia, gastric atrophy and bacterial overgrowth in the stomach. While randomized clinical trials to establish causality between long-term PPI use and gastric cancer are lacking, current evidence based on observational studies suggests PPIs are associated with an increased gastric cancer risk. However, opinions on causality remain divergent due to unmeasured and possible residual confounding in various studies. Our recent study has showed that even after H. pylori eradication, long-term PPI use is still associated with an increased risk of gastric cancer by more than twofold. Hence, long-term PPIs should be used judiciously after considering individual's risk-benefit profile, particularly among those with history of H. pylori infection. Further well-designed prospective studies are warranted to confirm the potential role of PPIs in gastric cancer according to baseline gastric histology and its interaction with other chemopreventive agents like aspirin, statins and metformin.

Signet Ring Cell Carcinoma of the Ampulla of Vater With Focal Neuroendocrine Differentiation of the Amphicrine Type: Report of a Case With Long-Term Survival

Carcinoma of the ampulla of Vater is an uncommon neoplasm and represents 0.5% of all gastrointestinal malignancies, being less common than carcinoma of the pancreas and bile ducts. The most common ampullary tumor is the adenocarcinoma with tubular growth pattern. Signet ring cell carcinoma is extremely rare. In this article, we report a case of signet ring cell carcinoma of the ampulla of Vater showing focal neuroendocrine amphicrine differentiation and intestinal phenotype, which occurred in a 49-year-old male who is still alive 7 years after surgery, without evidence of recurrence. This long-term survival might be attributed not only to the early stage of the disease but also to the neuroendocrine differentiation and the absence of genetic alterations.

Types of Gastric Carcinomas

Gastric cancer has reduced prevalence, but poor prognoses. To improve treatment, better knowledge of carcinogenesis and cells of origin should be sought. Stomach cancers are typically localized to one of the three mucosae; cardial, oxyntic and antral. Moreover, not only the stem cell, but the ECL cell may proliferate and give rise to tumours. According to Laurén, the classification of gastric carcinomas seems to reflect biological important differences and possible different cell of origin since the two subtypes, intestinal and diffuse, do not transform into the other and show different epidemiology. The stem cell probably gives rise to the intestinal type, whereas the ECL cell may be important in the diffuse type. Elevation of gastrin may be the carcinogenic factor for Helicobacter pylori as well as the recently described increased risk of gastric cancer due to proton pump inhibitor treatment. Therefore, it is essential to determine the role of the gastrin target cell, the ECL cell, in gastric carcinogenesis. Clinical trials with gastrin antagonists could improve prognoses in those with gastrin receptor positive tumours. However, further studies on gastric carcinomas applying relative available methods and with the highest sensitivity are warranted to improve our knowledge of gastric carcinogenesis.

Gastric adenocarcinoma is concurrent with metastatic neuroendocrine cancer treated with nivolumab and chemotherapy: A case report

Gastric adenocarcinoma concurrent with metastatic neuroendocrine cancer (NEC) is rare. In the present case report, a 39-year-old male was first pathologically diagnosed by gastric endoscopy as having a highly differentiated adenocarcinoma. Next, positron emission tomography-computed tomography examination and bone marrow biopsy confirmed extensive metastasis. Subsequently, the patient underwent 6 cycles of immunotherapy (nivolumab, 160 mg) and 5 cycles of chemotherapy based on the XELOX regimen (oxaliplatin + capecitabine). Following this, the patient received the final cycles of nivolumab and XELOX; however, the patient then succumbed. Further biopsy of the metastatic collarbone lymph nodes indicated NEC. Overall, the progression-free survival was ~3.5 months, and overall survival (OS) was ~6 months. The case presented the possibility of concurrent gastric adenocarcinoma and NEC in the clinic. In addition, the efficacy of a combined regimen such as immunotherapy and chemotherapy for such disorders still requires further validation in the future.

Proton pump inhibitors (PPIs) may cause gastric cancer - clinical consequences

Recently, two epidemiological studies showed that long-term treatment with proton pump inhibitors (PPIs) increased the risk of gastric cancer. It is well known that hypergastrinemia predisposes to gastric neoplasia in animals as well as man. Recently a study showed that hypergastrinemic patients had an increased risk of gastric cancer when followed for about 25 years. It is likely that hypergastrinemia is the pathogenic factor for gastric carcinogenesis due to PPI. PPI are the only group of drugs that causes long-term hypergastrinemia in the doses used in a clinical setting. Due to the likely carcinogenic effect, PPIs should be used carefully. Moreover, since the carcinogenic effect of Helicobacter pylori (Hp) infection also may be mediated by an increase in gastrin, Hp should be eradicated whenever treatment with PPI is initiated. In peptic ulcer disease Hp eradication is the treatment of choice. Gastro-oesophageal reflux disease (GERD) is the most prevalent condition leading to long-term use of inhibitors of gastric acid secretion. Only in severe oesophagitis should the treatment be initiated by PPIs, whereas histamine-2 (H-2) blockers ought to be the initial option in most cases of GERD particularly since PPI treatment induces tolerance to H-2 blockers. In the cases where long-term PPI treatment is necessary, the dose should be adjusted by the determination of chromogranin A, which in a way reflects 24-h gastrin exposure. Finally, due to latency of neoplasia, the use of PPI must be very restricted in children and young adults.

Not only stem cells, but also mature cells, particularly neuroendocrine cells, may develop into tumours: time for a paradigm shift

Stem cells are considered the origin of neoplasms in general, and malignant tumours in particular, and the stage at which the stem cells stop their differentiation determines the degree of malignancy. However, there is increasing evidence supporting an alternative paradigm. Tumours may develop by dedifferentiation from mature cells able to proliferate. Studies of gastric carcinogenesis demonstrate that mature neuroendocrine (NE) cells upon long-term overstimulation may develop through stages of hyperplasia, dysplasia, and rather benign tumours, into highly malignant carcinomas. Dedifferentiation of cells may change the histological appearance and impede the identification of the cellular origin, as seen with gastric carcinomas, which in many cases are dedifferentiated neuroendocrine tumours. Finding the cell of origin is important to identify risk factors for cancer, prevent tumour development, and tailor treatment. In the present review, we focus not only on gastric tumours, but also evaluate the role of neuroendocrine cells in tumourigenesis in two other foregut-derived organs, the lungs and the pancreas, as well as in the midgut-derived small intestine.

A common molecular signature of intestinal-type gastric carcinoma indicates processes related to gastric carcinogenesis

Gastric carcinoma (GC) is one of the most aggressive cancers and the second leading cause of cancer death in the world. According to the Lauren classification, this adenocarcinoma is divided into two subtypes, intestinal and diffuse, which differ in their clinical, epidemiological and molecular features. Several studies have attempted to delineate the molecular signature of gastric cancer to develop new and non-invasive screening tests that improve diagnosis and lead to new treatment strategies. However, a consensus signature has not yet been identified for each condition. Thus, this work aimed to analyze the gene expression profile of Brazilian intestinal-type GC tissues using microarrays and compare the results to those of non-tumor tissue samples. Moreover, we compared our intestinal-type gastric carcinoma profile with those obtained from populations worldwide to assess their similarity. The results identified a molecular signature for intestinal-type GC and revealed that 38 genes differentially expressed in Brazilian intestinal-type gastric carcinoma samples can successfully distinguish gastric tumors from non-tumor tissue in the global population. These differentially expressed genes participate in biological processes important to cell homeostasis. Furthermore, Kaplan-Meier analysis suggested that 7 of these genes could individually be able to predict overall survival in intestinal-type gastric cancer patients.

Metastatic spread in patients with gastric cancer

Background

The epidemiology of metastatic gastric cancer is unexplored because cancer registries seldom cover metastatic involvement apart from “present or not”. We used a novel approach by utilizing Swedish registers to assess metastatic spread in gastric cancer. To our knowledge, this is the first nationwide description of metastases in gastric cancer.

Results

The most common sites of metastasis were liver (in 48% of metastatic cancer patients), peritoneum (32%), lung (15%), and bone (12%). Metastases to the lung, nervous system, and bone were more frequent in cardia cancer and men, whereas non-cardia cancer more frequently metastasized within the peritoneum. Signet ring adenocarcinomas more frequently metastasized within the peritoneum, bone and ovaries, and less frequently to the lungs and liver compared with generic adenocarcinoma. The liver and the peritoneum were commonly single metastases while lung metastases occurred frequently together with liver metastases. The median survival in metastatic gastric cancer was 3 months, worst among those with bone and liver metastases (2 months).

Methods

A total of 7,559 patients with gastric cancer were identified. Metastatic patterns and survival depending on sex, age, stage, anatomical location (cardia and non-cardia), and histological type were assessed.

Conclusions

The patterns of metastasis differ notably depending on histological type. Cardia cancer exhibits a completely different metastatic behavior than non-cardia cancer. Awareness of the differing patterns may guide in tailored diagnosis of metastases. Survivors from cardia cancer would benefit from increased surveillance of extraperitoneal metastases. Bone metastases should be considered in patients with signet ring adenocarcinoma if symptoms emerge.

Maintenance therapy with proton pump inhibitors and risk of gastric cancer: a nationwide population-based cohort study in Sweden

OBJECTIVE

Proton pump inhibitors (PPIs) are among the most commonly prescribed drugs. Concerns have been raised about a potentially increased risk of gastric cancer following long-term use. Our aim is to assess the risk of gastric cancer associated with PPI use, taking into account underlying indications.

DESIGN

This is a population-based cohort study. Standardised incidence ratios (SIRs) and 95% CIs were calculated to compare the risk of gastric cancer among long-term PPI users with the corresponding background population, while taking confounding by indication into account.

SETTING

Population-based study in Sweden (2005-2012).

PARTICIPANTS

This study included virtually all adults residing in Sweden exposed to maintenance therapy with PPIs.

EXPOSURE/INTERVENTION

Maintenance use of PPIs, defined as at least 180 days during the study period. Maintenance use of histamine 2 receptor antagonist was evaluated for comparison reasons.

OUTCOME MEASURES

Gastric cancer (cardia and non-cardia), and subgroup analysis for gastric adenocarcinoma, as defined by the Swedish Cancer Registry.

RESULTS

Among 797 067 individuals on maintenance PPI therapy, the SIR of gastric cancer was over threefold increased (SIR=3.38, 95% CI 3.23 to 3.53). Increased SIRs were found in both sexes and all age groups, but were especially increased among PPI users younger than 40 years (SIR=22.76, 95% CI 15.94 to 31.52). Increased SIRs were found for each indication studied, including those without an association with gastric cancer, for example, gastro-oesophageal reflux (SIR=3.04, 95% CI 2.80 to 3.31), and those with a supposedly decreased risk, for example, aspirin users (SIR=1.93, 95% CI 1.70 to 2.18). The association was similar for cardia and non-cardia gastric cancer. Analyses restricted to adenocarcinoma showed similar results to those for all gastric cancers. Long-term users of histamine 2 receptor antagonists, which have the same indications as PPIs, were not at any increased risk.

CONCLUSIONS

Long-term PPI use might be an independent risk factor for gastric cancer. This challenges broad maintenance PPI therapy, particularly if the indication is weak.

Expression of the Cholecystokinin-B Receptor in Neoplastic Gastric Cells

Gastric cancer is an important disease due to its high mortality. Despite the decline in frequency, most cases are discovered late in its course, and most of the cancer patients die within a few years of diagnosis. In addition to Helicobacter pylori gastritis, gastrin is considered an important factor in the development of this disease, and thus, cholecystokinin-B receptor (CCKBR) becomes of interest. The aim of our study was to explore whether CCKBR is expressed in stomach cancers. Thirty-seven tumors from 19 men and 18 women diagnosed with either adenocarcinoma or neuroendocrine neoplasm (NENs) were included in this study. The tumors were classified into 29 adenocarcinomas and eight NENs. Immunohistochemistry with antibodies against chromogranin A (CgA), synaptophysin and CCKBR, and in situ hybridization with probes against CgA, CCKBR and histidine decarboxylase were used to further explore these tumors. Thirty-three (89%) of the tumors expressed CCKBR protein, whereas only 20 (54%) of all tumors expressed CCKBR mRNA. Of the 20 tumors expressing CCKBR mRNA, eight were NENs and 12 were adenocarcinoma. The highest amount of CCKBR was expressed in NEN. Interestingly, a high degree of co-expression of CCKBR and CgA was observed when the two markers were examined together with in situ hybridization. In conclusion, we found that all eight NENs expressed CCKBR and neuroendocrine markers in a majority of tumor cells. The same markers were also expressed in a proportion of adenocarcinomas supporting the view that gastrin is important in the development of gastric cancer.

Neuron-Specific Enolase as an Immunohistochemical Marker Is Better Than Its Reputation

The diagnosis of neuroendocrine neoplasms (NENs) may be challenging and is based on typical morphological features and positive staining for antibodies of neuroendocrine differentiation. Neuron-specific enolase (NSE) being a cytosolic marker may be useful in this setting. NSE is by many considered nonspecific, due to the finding of this marker in tumors considered not to be of neuroendocrine origin. Our aim was to determine whether this is true and whether NSE is more specific than previously realized. We examined 178 tumors (carcinomas and NENs) from breast, lung, stomach, and kidney using immunohistochemistry with the following markers: chromogranin A, synaptophysin, CD56, secretagogin, and NSE. Expression of NSE was compared with that of the other markers. NSE was expressed in 138 (78%) of all tumors. Of the NSE-expressing tumors, 95 (68%) cases expressed one or more additional neuroendocrine markers. The staining intensity and number of NSE-expressing tumor cells were highest among tumors of neuroendocrine origin and clear cell renal cell carcinomas. A positive association was found between NSE expression and the number of additional neuroendocrine markers expressed in each of the tumors. Practically all tumors positive for an accepted neuroendocrine marker also expressed NSE.

Gastrin and Gastric Cancer

Gastric cancer although occurring in reduced frequency is still an important disease, partly because of the bad prognosis when occurring in western countries. This decline in occurrence may mainly be due to the reduced prevalence of Helicobacter pylori (Hp) infection, which is the most important cause of gastric cancer. There exist many different pathological classifications of gastric carcinomas, but the most useful seems to be the one by Lauren into intestinal and diffuse types since these types seldom transform into the other and also have different epidemiology. During the nearly 30 years that have passed since the groundbreaking description of Hp as the cause of gastritis and gastric cancer, a continuous search for the mechanism by which Hp infection causes gastric cancer has been done. Interestingly, it is mainly atrophic gastritis of the oxyntic mucosa that predisposes to gastric cancer possibly by inducing hypoacidity and hypergastrinemia. There are many arguments in favor of an important role of gastrin and its target cell, the enterochromaffin-like cell, in gastric carcinogenesis. The role of gastrin in gastric carcinogenesis implies caution in the long-term treatment with inhibitors of gastric acid secretion inducing secondary hypergastrinemia, in a common disease like gastroesophageal reflux disease.

A case of mixed adenoneuroendocrine carcinoma of the stomach with focal intestinal metaplasia and hypergastrinemia

Among neuroendocrine neoplasms, mixed exocrine and endocrine characteristics with at least 30% of each component are classified into mixed adenoneuroendocrine carcinoma (MANEC), according to the 2010 World Health Organization classification. We experienced a rare case of MANEC of the stomach with focal intestinal metaplasia and hypergastrinemia. A 76-year-old Japanese male was diagnosed as having gastric adenocarcinoma and underwent total gastrectomy. The pathologic diagnosis was MANEC of the stomach accompanied by unusual mucosal atrophy without Helicobacter pylori infection, the characteristics of which were different from both type A and type B atrophic gastritis. The patient has a history of long-term use of a proton pump inhibitor. Additional serum chemistry examination using preoperatively obtained plasma from the patient revealed hypergastrinemia. The mechanism of gastric MANEC carcinogenesis is still unclear, but that might be correlated with unusual intestinal metaplasia and hypergastrinemia in this case.

Gastric mixed adenoneuroendocrine carcinoma: correlation of histologic characteristics with prognosis

Gastric mixed adenoneuroendocrine carcinomas (MANECs) are rare, with both the exocrine and neuroendocrine components exceeding 30% volume. Several classifications for MANECs have been proposed, yet they have not been clinically evaluated. The aim of this study was to evaluate the correlation between tumor grade, histologic characteristics, and prognosis of gastric MANECs. We collected eligible 14 cases in our series and 31 cases in the literature and compared the prognostic difference among gastric MANECs with different histologic characteristics. Gastric MANECs could be divided into subgroups according to tumor grade of the neuroendocrine component and adenocarcinoma types. The high grade and large proportion of neuroendocrine component correlated with aggressive behavior and a tendency of poor clinical outcome. Gastric MANECs with a poorly differentiated adenocarcinoma showed a significant lower survival rate than did MANECs with a differentiated adenocarcinoma or mucin-producing carcinoma (P = .0008). Gastric MANECs were a heterogeneous group with different tumor grades, histologic subtypes, combination patterns, and patient outcomes. Previous classifications were evaluated. This study proves that histologic characteristics correlate with clinical outcomes. Our findings are complements to the latest prognostic classification.

Histological characterisation and prognostic evaluation of 62 gastric neuroendocrine carcinomas

AIM OF THE STUDY

To determine the significance of expression of synaptophysin, chromogranin A, and Ki-67 and their association with clinicopathological parameters, and to find out the possible prognostic factors in gastric neuroendocrine carcinoma (G-NEC).

MATERIAL AND METHODS

We investigated the immunohistochemical features and prognosis of 62 G-NECs, and evaluated the association among expressions of synaptophysin, chromogranin A, and Ki-67, clinicopathological variables, and outcome.

RESULTS

Chromogranin A expression was found more commonly in small-cell NECs (9/9, 100%) than in large-cell NECs (27/53, 51%) (p = 0.008). No statistical significance was found in Ki-67 (p = 0.494) or synaptophysin (p > 0.1) expression between NEC cell types. Correlation analyses revealed that Ki-67 expression was significantly associated with mid-third disease of stomach (p = 0.005) and vascular involvement (p = 0.006), and had a trend of significant correlation with tumour relapse (p = 0.078). High expression of chromogranin A was significantly associated with histology of small-cell NECs (p = 0.008) and lesser tumour greatest dimension (p = 0.038). The prognostic significance was determined by means of Kaplan-Meier survival estimates and log-rank tests, and as a result, early TNM staging and postoperative chemotherapy were found to be correlated with longer overall survival (p < 0.05). Univariate analysis revealed associations between poor prognosis in NECs and several factors, including high TNM staging (p = 0.048), vascular involvement (p = 0.023), relapse (p = 0.004), and microscopic/macroscopic residual tumour (R1/2, p < 0.001). In a multivariate analysis, relapse was identified as the sole independent prognostic factor.

CONCLUSIONS

No significant correlation between survival and expression of synaptophysin, chromogranin A, or Ki-67 has been determined in G-NECs. Our study indicated that early diagnosis, no-residual-tumour resection, and postoperative chemotherapy were possible prognostic factors.

Three Molecular Subtypes of Gastric Adenocarcinoma Have Distinct Histochemical Features Reflecting Epstein-Barr Virus Infection Status and Neuroendocrine Differentiation

Current histopathologic classification schemes for gastric adenocarcinoma have limited clinical utility and are difficult to apply due to tumor heterogeneity. Elucidation of molecular subtypes of gastric cancer may contribute to our understanding of gastric cancer biology and to the development of new molecular markers that may lead to improved diagnosis, therapy, or prognosis. We previously demonstrated that Epstein-Barr virus (EBV)-infected gastric cancers have a distinct human gene expression profile compared with uninfected cancers. We now examine the histopathologic features characterizing infected (n=14) and uninfected (n=89) cancers; the latter of which are now further divided into 2 major molecular subtypes based on expression patterns of 93 RNAs. One uninfected gastric cancer subtype was distinguished by upregulation of 3 genes with neuroendocrine (NE) function (CHGA, GAST, and REG4 encoding chromogranin, gastrin, and the secreted peptide REG4 involved in epithelial cell regeneration), implicating hormonal factors in the pathogenesis of a major class of gastric adenocarcinomas. Evidence of NE differentiation (molecular, immunohistochemical, or morphologic) was mutually exclusive of EBV infection. EBV-infected tumors tended to have solid-type morphology with lymphoid stroma. This study reveals novel molecular subtypes of gastric cancer and their associated morphologies that demonstrate divergent NE features.

Does long-term profound inhibition of gastric acid secretion increase the risk of ECL cell-derived tumors in man?

OBJECTIVE

Since the description of ECL cell-derived tumors in rodents after long-term profound acid inhibition inducing hypergastrinemia, there has been concern that proton pump inhibitors (PPIs) could also do that in man. The recent description of a Spanish family with gastric ECL cell tumors at the age of about 30 years secondary to a defect in the proton pump due to mutation in the ATP4A gene clearly shows that hypergastrinemia alone also is sufficient to induce ECL cell neoplasia in man. The present review aims to evaluate the risk of gastric neoplasia secondary to gastric acid inhibition.

METHODS

Literature (MEDLINE) was searched for the role of the ECL cell in gastric carcinogenesis in animals and man in general and particularly secondary to long-term inhibition of acid secretion.

RESULTS

An important proportion of patients treated with PPI develops hypergastrinemia causing ECL cell hyperplasia and the first descriptions of ECL cell carcinoids secondary to PPI have been reported. The role of the ECL cell has hitherto been under estimated in gastric carcinogenesis in man where for instance the signet ring cell type of gastric carcinoma seems to originate from the ECL cell.

CONCLUSIONS

The first two of three steps in rodent ECL cell carcinogenesis (hyperplasia, carcinoid, and carcinoma) secondary to PPI dosing, have been described for man. It is every reason to believe that the final step, gastric carcinoma, will develop also in man. Clinical decisions should be based not only on so-called evidence based medicine, but also on physiological knowledge and animal studies.

Gastrin May Mediate the Carcinogenic Effect of Helicobacter pylori Infection of the Stomach

Gastric cancer occurs almost exclusively in patients with gastritis. Since Helicobacter pylori (Hp) was proved to cause gastritis, Hp was also expected to play a role in gastric carcinogenesis. Despite extensive studies, the mechanisms by which Hp cause gastric cancer are still poorly understood. However, there is evidence that the anatomical site of Hp infection is of major importance. Infection confined to the antral mucosa protects against gastric cancer but predisposes to duodenal ulcer, whereas Hp infection of the oxyntic mucosa increases the risk of gastric cancer. Hp infection does not predispose to cancers in the gastric cardia. In patients with atrophic gastritis of the oxyntic mucosa, the intragastric pH is elevated and the concentration of microorganisms in the stomach is increased. This does not lead to increased risk of gastric cancer at all anatomical sites. The site specificity of Hp infection in relation to cancer risk indicates that neither Hp nor the changes in gastric microflora due to gastric hypoacidity are carcinogenic per se. However, reduced gastric acidity also leads to hypergastrinemia, which stimulates the function and proliferation of enterochromaffin-like (ECL) cells located in the oxyntic mucosa. The ECL cell may be more important in human gastric carcinogenesis than previously realized, as every condition causing long-term hypergastrinemia in animals results in the development of neoplasia in the oxyntic mucosa. Patients with hypergastrinemia will far more often develop carcinomas in the gastric corpus. In conclusion, hypergastrinemia may explain the carcinogenic effect of Hp.

Upper gastrointestinal physiology and diseases

Nordic research on physiology and pathophysiology of the upper gastrointestinal tract has flourished during the last 50 years. Swedish surgeons and physiologists were in the frontline of research on the regulation of gastric acid secretion. This research finally led to the development of omeprazole, the first proton pump inhibitor. When Swedish physiologists developed methods allowing the assessment of acid secretion in isolated oxyntic glands and isolated parietal cells, the understanding of mechanisms by which gastric acid secretion is regulated took a great step forward. Similarly, in Trondheim, Norway, the acid producing isolated rat stomach model combined with a sensitive and specific method for determination of histamine made it possible to evaluate this regulation qualitatively as well as quantitatively. In Lund, Sweden, the identification of the enterochromaffin-like cell as the cell taking part in the regulation of acid secretion by producing and releasing histamine was of fundamental importance both physiologically and clinically. Jorpes and Mutt established a center at Karolinska Institutet in Stockholm for the purification of gastrointestinal hormones in the 1960s, and Danes followed up this work by excelling in the field of determination and assessment of biological role of gastrointestinal hormones. A Finnish group was for a long period in the forefront of research on gastritis, and the authors' own studies on the classification of gastric cancer and the role of gastrin in the development of gastric neoplasia are of importance. It can, accordingly, be concluded that Nordic researchers have been central in the research on area of the upper gastrointestinal physiology and diseases.

The normal neuroendocrine cells of the upper gastrointestinal tract lack E-cadherin

OBJECTIVE

E-cadherin plays a crucial role in the adhesion between epithelial cells and thus epithelial integrity. Moreover, germline mutations in the E-cadherin gene (CDH1) causing loss of E-cadherin function (adhesion) leads to hereditary gastric cancer of the diffuse type, according to Laurén. Even sporadic gastric carcinomas of the diffuse type often lose E-cadherin expression due to mutations. Lack of E-cadherin has been recorded at an early phase in such carcinomas. For 25 years, we have provided evidence for neuroendocrine (NE) cell origin of gastric carcinomas of diffuse type. The present study was, therefore, done to examine whether normal NE cells in the gastrointestinal tract express E-cadherin or not.

METHODS

During upper gastrointestinal endoscopy, biopsies were taken from normal oxyntic mucosa, gastric carcinoids, gastric carcinomas, and from normal duodenal mucosa. Tissues were examined by immunohistochemistry (IHC) using antibodies toward chromogranin A, synaptophysin, and E-cadherin. Isolated mucosal cells were prepared from biopsies of normal mucosa and examined by antibodies against the same markers by immunofluorescence.

RESULTS

Normal gastrointestinal NE cells did not express E-cadherin as assessed by IHC or immunocytochemistry. No expression of E-cadherin was found on tumor cells from gastric carcinoids or cancer of diffuse type examined by IHC.

CONCLUSION

Our findings, which are in contrast to some previous studies, may explain why there is a discrepancy between lack of atypia and malignant biological behavior of such tumors. Since they normally lack the adhesion molecule E-cadherin, reflected in their spread occurrence, only minor changes may result in malignant behavior.

Signet ring cell carcinoma of the ampulla of Vater: Immunophenotype and differentiation

Signet ring cell carcinoma (SRC) of the ampulla of Vater is extremely rare and the histogenesis remains unknown. In the present study, to investigate the immunohistochemical phenotypes, discuss the histological origin and evaluate the correlation between the immunohistochemical phenotypes and survival of ampullary SRC patients, a retrospective review was conducted. This included all ampullary carcinoma patients treated at The First Affiliated Hospital, College of Medicine, Zhejiang University, and was performed over a five-year period between 2008 and 2012. Eight resected ampullary SRC specimens were examined histopathologically and immunohistochemically, using cytokeratin (CK) and mucin (MUC) immunohistochemical phenotypes. Of all 162 patients with ampullary lesions, eight cases (4.9%) of ampullary SRC were identified. Immunohistochemical analyses of the eight cases revealed the positive expression of CK7 in five, CK19 in seven, CK20 in one, MUC1 in five, MUC2 in three, caudal-related homeobox transcription factor 2 in one, MUC5AC in seven and MUC6 in four of the eight cases, while loss of E-cadherin and β-catenin was observed in four of the eight cases. According to immunohistochemical classification, ampullary SRC can be classified into four subtypes: Intestinal (I), pancreatobiliary (PB), gastric and mixed types (composed of I mucosa lining and PB epithelium). Patients with the I-type ampullary SRC demonstrated a more favorable prognosis than that of patients with the PB-type ampullary SRC. Additionally, patients with ampullary SRC of I or PB type with gastric differentiation may have a worse prognosis than others. The coexpression of the E-cadherin/β-catenin complex may also indicate poor prognosis in PB-type ampullary SRC. In conclusion, the clinical five-year follow-up of the patients with pure SRC was more positive than that of those with I-, PB-, gastric- or mixed-type ampullary SRC. The coexpression of the E-cadherin/β-catenin complex may present a poor prognosis in the PB type of ampullary SRC.

The PAS positive material in gastric cancer cells of signet ring type is not mucin

PURPOSE

The purpose of this study is to assess the exocrine and neuroendocrine properties of tumour cells in diffuse gastric cancer with signet ring cell differentiation.

MATERIAL AND METHODS

Mucin mRNA and protein expressions (MUC1, 2, 3, 4, 5AC, 6 and MUC13) were assessed by immunohistochemistry and in situ hybridization. The neuroendocrine properties were evaluated by protein and mRNA expression of the general neuroendocrine markers chromogranin A and synaptophysin.

RESULTS

No MUC expression was observed in signet ring tumour cells including the amorphous substance in any of the nine cases. All cases showed immunoreactivity to synaptophysin, and seven out of nine cases immunoreactivity to chromogranin A in signet ring and non-signet ring tumour cells. Chromogranin A mRNA expression was observed in tumour cells in all samples with retained mRNA.

CONCLUSIONS

The lack of MUC protein and mRNA in signet ring tumour cells suggests the amorphous substance is not mucin. The lack of MUC mRNA expression in non-signet ring tumour cells questions exocrine differentiation in this tumour group. The abundant protein expression of the general neuroendocrine markers CgA and synaptophysin, and mRNA expression in tumour cells strengthens the hypothesis that this tumour group may be of neuroendocrine origin.

The regulation of gastric acid secretion - clinical perspectives

The purpose of this review, based upon 40 years of research, is to clear old controversies. The gastric juice is a strong acid with active enzymes (pepsin and lipase); ideal for killing swallowed microorganisms. Totally isolated rat stomach and histamine determination. Human gastric carcinomas were examined for ECL cell differentiation because tumours found in rodents after dosing with inhibitors of acid secretion were reclassified to be of ECL cell origin. The gastrin receptor is localized to the ECL cell only, where gastrin stimulates the function and growth. Drug-induced hypo-acidity induces hypergastrinaemia and ECL cell hyperplasia responsible for rebound acid hypersecretion. Every condition with long-term hypergastrinaemia disposes to ECL cell neoplasia. In man, both atrophic gastritis and gastrinoma lead to ECL cell carcinoids. Proton pump inhibitors induce hypergastrinaemia with ECL cell hyperplasia and ECL cell carcinoids that disappear when stopping treatment. The gastrin antagonist netazepide induces regression of ECL cell carcinoids due to atrophic gastritis. Human gastric carcinomas of diffuse type, particularly the signet-ring subtype, show ECL cell differentiation, suggesting involvement of gastrin in the carcinogenesis. Helicobacter pylori (Hp) causes gastritis and peptic ulcer, and when infecting the antrum only gives a slight hypergastrinaemia with acid hypersecretion predisposing to duodenal ulcer, but protecting from gastric cancer. When Hp infection spreads to oxyntic mucosa, it induces atrophy, reduced acid secretion and marked hypergastrinaemia and cancer.It is remarkable that the interaction between Hp and gastrin may explain the pathogenesis of most diseases in the upper gastrointestinal tract.

Follicular thyroid carcinoma with signet ring cell morphology: fine-needle aspiration cytology, histopathology, and immunohistochemistry

Thyroid follicular neoplasms with signet ring cell morphology represent a challenging cytological and histopathologic diagnosis. The low frequency of these neoplasms and their broad differential diagnosis contribute to this difficult scenario. Here, we present an exceptionally rare case of thyroid follicular carcinoma with signet ring cell morphology in a 62-year-old female. We analyze the characteristics in fine-needle aspiration cytology, histopathology, and immunohistochemistry and compare our results in a discussion with previous literature reports.

In situ hybridization in human and rodent tissue by the use of a new and simplified method

In situ hybridization (ISH) is a method that detects and localizes DNA or RNA in morphologically preserved tissue and cell preparations. The method is based on the principle that DNA or RNA will undergo hydrogen binding to complimentary sequences. Selective probes are labeled and used in order to detect specific sequences in tissues or cell preparations. Even though the method has improved over the past decades, there are still issues with sensitivity and specificity. The protocols are nonstandardized, and often time consuming due to multiple steps. In this paper, we have used a new and commercially available ISH kit for the detection of mRNA in formalin-fixed paraffin-embedded tissue. We have used both human and Mongolian gerbil tissue, and we evaluated mRNA expression of the neuroendocrine markers chromogranin A and histidine decarboxylase in both normal tissue and poorly differentiated tumor. In our experience, this method offers excellent sensitivity and specificity. The protocol is more standardized, and our results have been consistent. It is also less time consuming than conventional ISH protocols.

Neuroendocrine carcinoma of the stomach: clinicopathological and immunohistochemical evaluation

Neuroendocrine carcinoma (NEC) of the stomach is an uncommon disease. Because of its rarity, the clinicopathological features are unclear, and there is no consensus on the optimal treatment strategy. This study included five consecutive patients with gastric NEC who underwent surgery from July 2001 to August 2011. Clinical presentation, tumor location, tumor morphology and size, pathology and immunohistochemistry results, and treatment outcome were analyzed retrospectively and discussed. The study cohort of four men and one woman ranged in age from 52 to 84 years, with a median age of 72 years. Positive rates of neuroendocrine markers were 40 % for chromogranin A, 60 % for synaptophysin, 60 % for CD56, 40 % for neuron-specific enolase, and 100 % for p53 protein. Median number of lymph node metastases per patient was 10, with severe lymphatic and venous infiltration, and high Ki-67 labeling index (60-90 %) reported for all patients. Median tumor size was 6 cm. Stage IV disease was diagnosed in three patients; the other two patients showed stage IIIA tumors. After a mean follow-up of 29.8 months, two of the five patients had died of the disease. Although rare, gastric NECs deserve particular attention because of their strong malignant potential associated with an extremely poor prognosis. Such carcinomas demand an aggressive surgical approach followed by chemotherapy and multimodality adjuvant therapy.

Paraneoplastic neurological syndromes associated with gastric cancer: a case report and review of the literature

Paraneoplastic neurological syndromes (PNS) are associated with small-cell lung cancer, breast and gynecological cancers. We describe a gastric neoplasm presented with neurological symptoms. A 74-year-old male presented with tonic-clonic seizures. Initial investigations were normal; however, brain magnetic resonance imaging showed abnormal signal intensity in the hippocampi. A diagnosis of PNS was suspected. The patient was then diagnosed with a gastric neuroendocrine carcinoma with N-type voltage-gated calcium channel antibodies. The neurological impairments improved after the primary was resected and the patient remains free of cancer and paraneoplastic syndrome. We reviewed 10 cases of PNS associated with gastric cancer and found several characteristics: (1) older men, (2) neuroendocrine component or predominance, (3) oncological outcome for patients with PNS is better than for patients without PNS, and (4) neurological impairment is diagnosed 6 months prior to the diagnosis of gastric malignancy. In conclusion, elderly men with symptoms suggestive of PNS should be investigated for a gastric neuroendocrine malignancy.

Genetics and molecular pathology of gastric malignancy: Development of targeted therapies in the era of personalized medicine

Gastric malignancy constitutes a major cause of cancer deaths worldwide. Despite recent advances in surgical techniques combined with neoadjuvant chemotherapy and radiotherapy approaches, patients with advanced disease still have poor outcomes. An emerging understanding of the molecular pathways that characterize cell growth, cell cycle, apoptosis, angiogenesis, invasion and metastasis has provided novel targets in gastric cancer therapy. In this review, recent advances in the understanding of molecular tumorigenesis for common gastric malignancies are discussed. We also briefly review the current targeted therapies in the treatment of gastric malignancies. Practical insights are highlighted including HER2 testing and target therapy in gastric adenocarcinoma, morphologic features and molecular signatures of imatinib-resistance GISTs, and recent investigations aimed at tumor-specific therapy for neuroendocrine tumors.