A 15-year experience with gastric neuroendocrine tumors: Does type make a difference?

Last decade of advances in gastric neuroendocrine tumors: Innovations, challenges, and future directions

BACKGROUND

Gastric neuroendocrine tumors (G-NETs) are rare tumors originating from enterochromaffin-like cells, with an incidence of 0.4 per 100000 annually. There are three main types: (1) Type I, linked to chronic atrophic gastritis and hypergastrinemia, makes up 75%–80% of G-NETs; (2) Type II, associated with Zollinger-Ellison syndrome (ZES) and multiple endocrine neoplasia, comprises 5%; and (3) Type III, sporadic tumors with a higher metastatic potential, accounting for 15%–25%. Diagnosis involves endoscopy, biopsy, and histological examination. Additional methods include serum gastrin testing, immunohistochemistry, and imaging techniques such as computer tomography or magnetic resonance imaging for detecting metastasis. Type I treatment usually involves endoscopic resection (ER), with surgical resection for recurrence. Somatostatin analogs (SSAs) can reduce tumor size, and the prognosis is generally excellent. Type II treatment centers on surgical removal of the gastrinoma, with ER for smaller lesions and SSAs for symptom management. Type III requires surgical resection (partial or total gastrectomy) with lymph node dissection, and possibly chemotherapy. This type has a worse prognosis due to its aggressive nature. Emerging treatments like Peptide Receptor Radionuclide Therapy are promising for advanced cases, and ongoing research into immunotherapies is expanding future treatment options. Regular endoscopic follow-up is crucial to monitor for recurrence or metastasis across all types. Our literature review explores the current perspectives on G-NETs and highlights the importance of further research to improve diagnostic precision and treatment, particularly for those associated with less favorable cases.

AIM

To improve diagnostic precision and treatment, particularly for those associated with less favorable cases.

METHODS

A systematic search was conducted in PubMed, Scopus, and Web of Science until September 2024. Two independent reviewers screened titles, abstracts, and full texts for eligibility based on G-NET treatment in adults. Eligible studies included cohort studies, clinical trials, case series, and case reports, while in vitro, pediatric, and non-English studies were excluded. Relevant data were extracted independently, and disagreements were resolved through discussion. Study quality was assessed using appropriate tools.

RESULTS

G-NETs are rare, classified into three types: (1) Type I; (2) Type II; and (3) Type III. Type I G-NETs, often associated with chronic atrophic gastritis, are typically slow-growing and low-grade, with favorable outcomes following surgical resection. Type II G-NETs arise in hypergastrinemia conditions like multiple endocrine neoplasia and ZES, showing moderate malignancy risk. Type III G-NETs, the most aggressive and least common, present with distant metastases and poor prognosis. Diagnosis relies on endoscopy, imaging, and biomarkers like chromogranin A. Treatment varies by type, ranging from ER to aggressive surgery and chemotherapy for advanced cases. Regular follow-up is essential to monitor recurrence, particularly for type III G-NETs.

CONCLUSION

G-NETs require tailored diagnosis and treatment based on type and stage. Types I and II generally have better prognosis, while types III and IV are linked to poorer outcomes due to invasion and metastasis. Treatment strategies vary from ER for type I to extensive surgery for type III. Emerging therapies, like somatostatin analogs and peptide-receptor radionuclide therapies, show promise in advanced cases. Further research is essential to improve early diagnosis and treatment, particularly for high-risk lesions.

Classification of Gastric Neuroendocrine Tumors and Associations With Survival

BACKGROUND AND OBJECTIVES

Not all gastric neuroendocrine tumors (GNETs) may be classified into one of the three described clinicopathologic subtypes. The purpose of this study was to better characterize GNET subtypes and associated outcomes.

METHODS

Patients treated for GNET at our institution (1995-2021) were identified. Pathologic specimens of tumors that could not be classified as type 1, 2, or 3 were further reviewed. GNETs were categorized as proton pump inhibitor (PPI)-associated based on changes in the background gastric mucosa consistent with PPI use. Distant metastasis at presentation (DM) and disease-specific survival (DSS) were evaluated.

RESULTS

Among 246 patients, there were 164 (67%) type 1, 5 (2%) type 2, 52 (21%) type 3, and 18 (7%) PPI-associated GNETs. Seven (3%) tumors remained unclassified. DM was more frequent with type 3 GNETs (38%) than type 1 (1%), type 2 (20%), or PPI-associated tumors (11%, p < 0.001). Ten-year DSS rates were 100% for type 1, 53% (95% confidence interval [CI], 38%-75%) for type 3, and 80% (95% CI, 58%-100%) for PPI-associated tumors (p < 0.001). GNET subtype, race, and DM were independently associated with DSS.

CONCLUSIONS

PPI-associated tumors may represent a distinct GNET subtype with intermediate outcomes. Other factors should also be considered in overall prognosis.

Advances in Endoscopic Diagnosis and Treatment of Gastric Neuroendocrine Neoplasms

Gastric neuroendocrine neoplasms refer to a group of diseases that are relatively rare. They can be classified into three subtypes based on their clinical and histopathological features, and there are significant differences in diagnosis, treatment, and prognosis among the different subtypes. The incidence of gastric neuroendocrine neoplasms has been increasing globally in recent years with the localized disease being particularly evident. Gastrointestinal endoscopy is of irreplaceable importance for the diagnosis and management of g-NENs. Endoscopy with biopsy is the gold standard for the diagnosis of g-NENs. Ultrasound endoscopy can assess the depth of tumor invasion and the presence of lymphatic metastases, which is important for the development of treatment strategies. Meanwhile, for some small and low-risk lesions, endoscopic surveillance or endoscopic resection has satisfactory therapeutic results and prognosis. This means that even though the incidence has increased, advances in endoscopic techniques have allowed more patients to adopt a relatively conservative treatment strategy. However, the criteria for patients suitable for endoscopic surveillance or endoscopic resection remain controversial.

Gastric Neuroendocrine Tumors (g-NETs): A Systematic Review of the Management and Outcomes of Type 3 g-NETs

PURPOSE

to collect data from real-life experiences of the management of type 3 g-NETs and identify possible prognostic factors that may impact the decision-making process.

METHODS

We performed a systematic review of the literature on type 3 g-NET management using the PubMed, MEDLINE, and Embase databases. We included cohort studies, case series, and case reports written in the English language.

RESULTS

We selected 31 out of 556 articles from between 2001 and 2022. In 2 out of the 31 studies, a 10 mm and 20 mm cut-off size were respectively associated with a higher risk of gastric wall infiltration and/or lymph node and distant metastasis at diagnosis. The selected studies reported a higher risk of lymph node or distant metastasis at diagnosis in the case of muscularis propria infiltration or beyond, irrespective of the dimensions or grading. From these findings, size, grading, and gastric wall infiltration seem to be the most relevant factors in management staff making choices and prognoses of type 3 g-NET patients. We produced a hypothetical flowchart for a standardized approach to these rare diseases.

CONCLUSION

Further prospective analyses are needed to validate the prognostic impact of the use of size, grading, and gastric wall infiltration as prognostic factors in the management of type 3 g-NETs.

Metastatic multiple gastric neuroendocrine tumors with a long history of proton pump inhibitor use: A case report

It is widely accepted that gastric neuroendocrine tumors (NETs) develop due to enterochromaffin-like (ECL) cell proliferation following exposure to hypergastrinemia, which causes hyperplastic-dysplastic-neoplastic changes. Here we describe the case of a 46-year-old female patient diagnosed with metastatic NETs by liver biopsy and evaluated at an external center. At our hospital, nodular structures extending from the cardia to the antrum were observed by gastroscopy, considered the primary tumor focus. Histopathological examination revealed a trabecular-insular pattern, with microNETs consisting of monotone cells with round-oval nuclei and surrounding neuroendocrine cell hyperplasia foci and fundic gland polyps. The patient had a history of regular proton pump inhibitor (PPI) use for 10 years and a serum gastrin of 9240 pg/mL. A 3-cm metastatic lesion in the left lobe of the liver was observed in whole-body imaging with octreotide. By gastrectomy, we observed a large number of nodular lesions in the corpus-antrum and a 3-cm diameter lesion in the hepatectomy material. Histopathological examination revealed NETs in multiple foci with submucosal invasion in the stomach. The Ki-67 proliferative index was 3%. Metastatic tumors of similar morphology were found in the liver and three of the greater curvature lymph nodes. We made a diagnosis of multiple gastric NETs (Grade 2). In Type I gastric NETs, the neuroendocrine cell proliferation spectrum up to NET is observed as a result of hypergastrinemia due to atrophic gastritis. Also, in experimental studies, prolonged hypergastrinemia has been reported to cause ECL cell neoplasms in animals treated with PPIs. Although our case could be accepted as Type 1 NET, the possibility of developing NET secondary to long-term PPI use should also be considered.

Is local excision sufficient in selected grade 1 or 2 type III gastric neuroendocrine neoplasms?

PURPOSE

Type III gastric neuroendocrine neoplasms (g-NENs) have historically been regarded as aggressive tumours, hence current guidelines advocate radical surgery with lymph node dissection. Data on the roles of endoscopic or less extensive surgical resections are more limited. The aim of our study is to evaluate the clinicopathological features and long-term outcomes of patients undergoing endoscopic or limited surgical resection for localised grade 1 or 2 type III g-NENs when compared to radical surgery.

METHODS

Retrospective analysis of all patients diagnosed with a localised grade 1 or 2 type III g-NENs across six tertiary NEN centers between 2006 and 2019.

RESULTS

Forty-five patients were diagnosed with a potentially resectable grade 1 or 2 type III g-NEN of whom 36 underwent either endoscopic or surgical resection. No statistically significant differences were found between the three resection groups in terms of patient age, tumour location, grade or size. Only tumour size was found to be significantly associated with poor clinical outcome (p = 0.012) and ROC curve analysis identified tumour size >10 mm as a negative predictor (AUC:0.8030, p = 0.0021). Tumours >10 mm were also more likely to be associated with lymph node metastases on imaging and histology (p = 0.039 and p = 0.026 respectively).

CONCLUSIONS

Localised grade 1 or 2 type III g-NENs had a good prognosis in this series. Tumour size >10 mm was the most significant prognostic factor affecting patient outcome. Endoscopic resection or limited surgical resection is feasible and safe in small type III g-NENs which demonstrate favourable grade 1/2, well differentiated histology.

Management of Other Gastric and Duodenal Neuroendocrine Tumors

Gastric and duodenal neuroendocrine tumors (NETs) are increasing in incidence as a result of increased detection and awareness of neuroendocrine tumors as distinct tumor types. The three types of gastric NETs and duodenal NETs have different etiologies and tumor-specific factors, such as grade, location, and hormone-production, and the clinical settings influence management. Options for treatment include removal by local endoscopic resection and surgical resection. Medical therapy is used to treat the inciting condition or as systemic therapy in advanced disease. Although the overall prognosis for most is good, higher grade tumors behave aggressively and have reduced survival.

Gastric Neuroendocrine Tumors: Reappraisal of Type in Predicting Outcome

BACKGROUND

Type I gastric neuroendocrine tumors (GNETs) are typically managed either expectantly or endoscopically. In contrast, locoregional surgery has been recommended for patients with type III GNETs because of the risk of metastasis. This study aimed to identify predictors of outcome independent of type in a contemporary cohort of GNET patients.

METHODS

A single-institution retrospective cohort study of 121 patients with a pathologic diagnosis of primary GNET between January 2009 and June 2019 was performed. GNETs were designated as type 1 (n = 74) if atrophic gastritis was present, or as type III (n = 47) in the absence of atrophic gastritis. Demographic, clinical, and histopathologic factors were examined using Kaplan-Meier and multivariable Cox regression to assess the impact of various factors on recurrence and overall survival.

RESULTS

Median follow-up for the entire cohort was 62.7 months. While there was no difference in OS in patients with different GNET types (p = 0.10), higher tumor grade (p = 0.02) and presence of nodal or distant metastases (p = 0.02) predicted worse survival on multivariable analysis. Among type III GNET patients, those with small (< 0.5 cm), grade 1 lesions ("low-risk") were less likely to develop metastases (0% versus 33%, p < 0.01) and more likely to survive (100% versus 67%, p < 0.01) at 5 years.

CONCLUSIONS

Size and tumor grade predict recurrence and survival in patients with GNETs irrespective of type. Small, low-grade type III GNETs are associated with minimal risk of progression and may be managed accordingly.

Is endoscopic resection appropriate for type 3 gastric neuroendocrine tumors? Retrospective multicenter study

BACKGROUND

Gastrectomy with lymphadenectomy is recommended for type 3 gastric neuroendocrine tumors (G-NETs). This study aimed to identify the risk factors for lymph node metastasis (LNM) arising from G-NETs to assess the suitability of endoscopic resection (ER).

METHODS

Nationwide clinicopathological data of patients with type 3 G-NETs who underwent surgery or ER were collected. A single pathologist graded the histological tumor specimens.

RESULTS

Among 176 cases from 53 institutions, 144 were eligible for analysis (90 NET-G1 and 54 NET-G2 grade, 8-mm median-size tumors). Of these, 63 patients had undergone ER (15 with additional surgeries). Histological data regarding LNM were available for 93 surgical patients. LNM was confirmed in 15 (16%) tumors and was correlated with tumor diameter, invasion depth, and tumor grade. LNM was negative in six tumors ≤5 mm, confined to the mucosa or submucosa, with a grade of G1, and without lymphovascular invasion, but the number of cases was too small to propose ER indications. Among 48 patients treated with ER alone, only one developed recurrence; no mortality was observed at follow-up, although many patients were classified with SM2/NET-G2/tumors >5 mm. This suggests that not all LNMs arising from small G-NETs are fatal.

CONCLUSION

Gastrectomy with lymphadenectomy for type 3 G-NETs is recommended on the basis of LNM. However, ER for type 3 G-NETs ≤10 mm, confined to the mucosa or submucosa, with a grade of G1 has shown excellent survival outcomes despite the risk of LNM, and therefore, could be an alternative treatment option.

Effects of tumor types on treatment strategy formulation and prognostic evaluation of gastric neuroendocrine tumors

Aim: The effects of different types of gastric neuroendocrine tumors (G-NETs) on treatment strategy formulation and prognostic evaluation still remain controversial due to their rarity. Methods: 187 patients diagnosed with G-NETs were subdivided into four types based on the pathophysiology, etiology and presentation. Results: Type I, II G-NETs >1.0 cm and type III, IV G-NETs >2.0 cm are proved with aggressive behavior (p < 0.05). Type III G-NETs with higher Ki-67 index and tumor stage showed more invasive potential than type I and II G-NETs (p < 0.05). Endoscopic resection is the primary treatment for type I, II G-NETs, while surgical combined with chemotherapy is associated with favorable outcomes for type IV G-NETs. Conclusion: The clinical classifications of G-NETs are of great significance for the choice of treatment and the evaluation of prognosis.

Gastric neuroendocrine neoplasms type 1: A systematic review and meta-analysis

BACKGROUND

To date, the histopathological parameters predicting the risk of lymph node (LN) metastases and local recurrence, associated mortality and appropriateness of endoscopic or surgical resection in patients with gastric neuroendocrine neoplasms type 1 (GNENs1) have not been fully elucidated.

AIM

To determine the rate of LN metastases and its impact in survival in patients with GNEN1 in relation to certain clinico-pathological parameters.

METHODS

The PubMed, EMBASE, Cochrane Library, Web of Science and Scopus databases were searched through January 2019. The quality of the included studies and risk of bias were assessed using the Newcastle-Ottawa Scale (NOS) in accordance with the Cochrane guidelines. A random effects model and pooled odds ratios (OR) with 95%CI were applied for the quantitative meta-analysis.

RESULTS

We screened 2933 articles. Thirteen studies with 769 unique patients with GNEN1 were included. Overall, the rate of metastasis to locoregional LNs was 3.3% (25/769). The rate of LN metastases with a cut-off size of 10 mm was 15.3% for lesions > 10 mm (vs 0.8% for lesions < 10 mm) with a random-effects OR of 10.5 (95%CI: 1.4 -80.8; heterogeneity: P = 0.126; I 2 = 47.5%). Invasion of the muscularis propria was identified as a predictor for LN metastases (OR: 17.2; 95%CI: 1.8-161.1; heterogeneity: P = 0.165; I 2 = 44.5%), whereas grade was not clearly associated with LN metastases (OR: 2; 95%CI: 0.3-11.6; heterogeneity: P = 0.304; I 2 = 17.4%). With regard to GNEN1 local recurrence, scarce data were available. The 5-year disease-specific survival for patients with and without LN metastases was 100% in most available studies irrespective of the type of intervention. Surgical resection was linked to a lower risk of recurrence (OR: 0.3; 95%CI: 0.1-1.1; heterogeneity: P = 0.173; I 2 = 31.9%). The reported complication rates of endoscopic and surgical intervention were 0.6 and 3.8%, respectively.

CONCLUSION

This meta-analysis confirms that tumor size ≥ 10 mm and invasion of the muscularis propria are linked to a higher risk of LN metastases in patients with GNEN1. Overall, the metastatic propensity of GNEN1 is low with favorable 5-year disease-specific survival rates reported; hence, no clear evidence of the prognostic value of LN positivity is available. Additionally, there is a lack of evidence supporting the prediction of local recurrence in GNEN1, even if surgery was more often a definitive treatment.

Gastric carcinoids: Does type of surgery or tumor affect survival?

BACKGROUND

Gastric carcinoids are rare neuroendocrine tumors of the gastrointestinal tract. They are typically managed according to their etiology. However, there is little known about the impact of surgical strategy on the long-term outcomes of these patients.

METHODS

All patients who underwent resection of gastric carcinoids at 8 institutions from 2000 to 2016 were analyzed retrospectively. Tumors were stratified according to subtype (I, II, III, IV) and resection type (local resection, LR or formal gastrectomy, FG). Clinicopathological parameters, recurrence-free (RFS) and overall survival (OS) were compared between groups.

RESULTS

Of 79 patients identified with gastric carcinoids, 34 had type I lesions associated with atrophic gastritis, 4 had type II lesions associated with a gastrinoma, 37 had type III sporadic lesions, and 4 had type IV poorly-differentiated lesions. The mean age of presentation was 56 years in predominantly Caucasian (77%) and female (63%) patients. Mean tumor size was 2.4 cm and multifocal tumors were found in 24 (30%) of patients with the majority occurring in those with type I tumors. Lymph node positive tumors were seen in 15 (19%) patients and 7 (8%) had M1 disease; both most often in type IV followed by type III tumors. R0 resection was achieved in 56 (71%) patients while 15 (19%) had R1 resections and 6 (8%) R2 resections. Patients with type I and III tumors were equally likely to have a LR (50% and 43% respectively) compared to FG while those with type II and IV all had FG with one exception. Type IV tumors had the poorest RFS and OS while Type II tumors had the most favorable RFS and OS (p < 0.04 and p < 0.0004, respectively). While there was no difference in RFS in those patients undergoing FG versus LR, OS was worse in the FG group (p < 0.017). This trend persisted when type II and type IV groups were excluded (p < 0.045).

CONCLUSION

Gastric carcinoid treatment should be tailored to tumor type, as biologic behavior rather than resection technique is the more important factor contributing to long-term outcomes.

Further Classification for Node-Positive Gastric Neuroendocrine Neoplasms

BACKGROUND

For gastric neuroendocrine neoplasms (GNEN), the current AJCC lymph node (N) stage classifies patients into N0/N1 disease (with/without locoregional nodal metastases); however, this does not account for the number of involved nodes. The objective of this study was to evaluate the prognostic significance of the number of involved locoregional nodes among resected GNEN.

METHODS

The National Cancer Database (2004-2014) was queried for GNEN patients who had undergone partial/total gastrectomy with known nodal status. Nearest-neighborhood grouping was used to identify survival clusters by number of metastatic nodes and to use these groupings to construct a new N classification (pN). External validation was performed using the SEER database. Kaplan-Meier analysis and Cox regression models were used to assess the prognostic strength of the pN classification.

RESULTS

One thousand two hundred seventy-five patients met study inclusion criteria. Patients with 1-6 positive nodes (pN1) demonstrated a distinct survival pattern from patients with > 6 positive nodes (pN2) as well as those with no positive nodes (N0) {5-year OS N0: 80% (95% CI 77-83%) vs. 65% (95% CI 61-69%) vs. 43% (95% CI 33-53%), p < 0.001}. On external validation, the pN classification demonstrated strong discriminatory ability for survival {5-year OS N0: 70% (95% CI 65-75%) vs. pN1:53% (95% CI 46-59%) vs. pN2:18% (95% CI 9-29%), p < 0.001}. On multivariable analysis, the pN classification remained an independent predictor of OS.

CONCLUSIONS

The number of metastatic lymph nodes is an independent prognostic factor in GNEN. Current AJCC N1 disease contains two groups of patients with distinctive prognoses, hence needs to be subclassified into pN1 (1-6 positive lymph nodes) and pN2 (> 6 positive nodes).

Gastric carcinoid tumor after laparoscopic gastric banding: Case report of a patient with weight regain

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Although carcinoid accounts for only 1% of all the gastric tumors it is the most common type of neuroendocrine neoplasia of the stomach.

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Its increased incidence among the obese population in relation to the general population.

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Resective gastric bypass may be considered as a treatment of choice for patients who after bariatric surgery were diagnosed with gastric carcinoid and weight regain.

Introduction

Although carcinoid tumours are a rare gastrointestinal neoplasm with an incidence rate of 1–2.5 cases per 100 000 inhabitants, they are the most common neuroendocrine tumour of the stomach.

Presentation of case

A 70-year-old-man consulted for epigastric pain and dyspepsia symptoms. His past medical and surgical history included obesity (BMI: 53.9 kg/m²), hypertension, hyperlipidemia, diabetes mellitus type 2, cardiac failure and a surgical treatment with laparoscopic gastric banding. For the analysis and control of the gastric banding an upper gastrointestinal endoscopy was performed evidencing many small polyps in the gastric antrum, body and fundus. The histopathological examination of the resected specimen revealed a well differentiated carcinoid. Laparoscopic surgery for the removal of the gastric banding and the subtotal gastrectomy leaving a small gastric remnant of approximately 2-cm in size similar to the pouch of a bypass was done. Twelve months after surgery the patient presented a body mass index of 36.6 kg /m².

Discussion

Gastric carcinoid increased incidence among the obese population, although the causing mechanisms are not clear, yet it is likely that metabolic and hormonal effects of the obesity play a role. The resection may be performed either endoscopically when the lesions are small, or surgically according to the tumor type and size.

Conclusion

The resective gastric bypass or gastrectomy with anastomosis by Roux- en- Y bypass may be considered as a treatment of choice for patients who after bariatric surgery were diagnosed with gastric carcinoid and weight regain.

SSAT State-of-the-Art Conference: Current Surgical Management of Gastric Tumors

INTRODUCTION

The current era of gastric surgery is marked by low morbidity and mortality rates, innovative strategies to approach resections with a minimally invasive fashion or hyperthermic intraperitoneal chemotherapy (HIPEC), as well as improved understanding of the biology of sporadic and hereditary stromal, neuroendocrine, and epithelial malignancies.

METHODS

In 2017, the Society for Surgery of the Alimentary Tract convened a State-of-the-Art Conference on Current Surgical Management of Gastric Tumors with both international experts and emerging leaders in the field of gastric surgery.

RESULTS

Martin D. McCarter, MD of the University of Colorado discussed the current management of gastric gastrointestinal stromal tumors (GIST). Kaitlyn J. Kelly, MD of the University of California, San Diego discussed the management of gastric carcinoid tumors. Jeffrey A. Norton of Stanford University discussed recent advances in the management of gastric adenocarcinoma including a focus on hereditary diffuse gastric cancer (HDGC). Joseph Kim, MD of Stony Brook University discussed a systematic approach to minimally invasive gastrectomy for cancer. Joyce Wong, MD of Pennsylvania State University discussed the role for cytoreductive surgery (CRS) and HIPEC for gastric adenocarcinoma.

CONCLUSIONS

This review provides gastrointestinal surgeons with a concise update on the current surgical management of gastric tumors.

When should genetic testing be performed in patients with neuroendocrine tumours?

Neuroendocrine tumours (NETs) are a heterogenous group of tumours arising from neuroendocrine cells in several sites around the body. They include tumours of the gastroenteropancreatic system, phaeochromocytoma and paraganglioma and medullary thyroid cancer. In recent years, it has become increasingly apparent that a number of these tumours arise as a result of germline genetic mutations and are inherited in an autosomal dominant pattern. The number of genes implicated is increasing rapidly. Identifying which patients are likely to have a germline mutation enables clinicians to counsel patients adequately about their future disease risk, and allows for earlier detection of at-risk patients through family screening. The institution of screening and surveillance programmes may in turn lead to a major shift in presentation patterns for some of these tumours. In this review, we examine the features which may lead a clinician to suspect that a patient may have an inherited cause of a NET and we outline which underlying conditions should be suspected. We also discuss what type of screening may be appropriate in a variety of situations.

Neuroendocrine Tumors of the Stomach

Gastric neuroendocrine tumors (NETs) are classified into three types. Type I gastric NETs are associated with chronic atrophic gastritis. They have a good prognosis and endoscopic resection is the mainstay of treatment. Type II gastric NETs are caused by hypergastrinemia. They have a poorer prognosis, and resection is required to control the disease. Endoscopic versus surgical resection is recommended for the gastric lesion. Type III gastric NETs are sporadic and not associated with any specific condition. They have the worst prognosis with the highest rate of metastatic disease, and oncologic resection is recommended. Medical therapies have some role.

Insights into gastric neuroendocrine tumors burden

Type 1 gastric neuroendocrine tumors (gNETs) are usually small lesions, restricted to mucosal and sub-mucosal layers of corpus and fundus, with low aggressive behavior, for the majority of cases. Nevertheless, some cases present aggressive behavior. The increasing incidence of gNETs brings together a new relevant problem: how to identify potentially aggressive type 1 gNETs. The challenging problem seems to be finding out signs or features able to predict potentially aggressive cases, allowing a tailored approach, since the involved societies dedicated to provide guidelines for management of these neoplasms apparently failed in producing staging systems able to accurately predict prognosis of these tumors. Additionally, it is also important to try to find out explanations for increasing incidence, as well as to identify potential targets aiming to reach better control of this neoplasia. Here, we discuss potential pathways implicated in aggressive behavior, as well as new strategies to improve clinical management of these tumors.