Type I gastric carcinoids: a prospective study on endoscopic management and recurrence rate

Advances in the diagnosis and treatment of gastric neuroendocrine neoplasms

Gastric neuroendocrine neoplasms (g-NENs) are a group of heterogeneous tumors arising from the endocrine cells of stomach. Most g-NENs progresses slowly and have a long disease course; however, some other g-NENs grow rapidly, similar to the progression of gastric adenocarcinoma. g-NENs have complex and diverse clinical manifestations and their prognosis and treatment strategies depend highly on clinical subtype, pathological grade, tumour stage, and other factors. Due to their low prevalence, most clinicians have limited knowledge about g-NENs. Missed diagnosis and excessive/inadequate treatment is common in clinical settings. Thus, the diagnosis and treatment of g-NENs needs to be further standardized.

Netazepide, a gastrin/cholecystokinin-2 receptor antagonist, can eradicate gastric neuroendocrine tumours in patients with autoimmune chronic atrophic gastritis

AIMS

Netazepide, a gastrin/cholecystokinin 2 receptor antagonist, once daily for 12 weeks reduced the number of tumours and size of the largest one in 16 patients with autoimmune chronic atrophic gastritis (CAG), achlorhydria, hypergastrinaemia and multiple gastric neuroendocrine tumours (type 1 gastric NETs), and normalized circulating chromogranin A (CgA) produced by enterochromaffin-like cells, the source of the tumours. The aim was to assess whether longer-term netazepide treatment can eradicate type 1 gastric NETs.

METHODS

After a mean 14 months off netazepide, 13 of the 16 patients took it for another 52 weeks. Assessments were: gastroscopy; gene-transcript expression in corpus biopsies using quantitative polymerase chain reaction; blood CgA and gastrin concentrations; and safety assessments.

RESULTS

While off-treatment, the number of tumours, the size of the largest one, and CgA all increased again. Netazepide for 52 weeks: cleared all tumours in 5 patients; cleared all but one tumour in one patient; reduced the number of tumours and size of the largest one in the other patients; normalized CgA in all patients; and reduced mRNA abundances of CgA and histidine decarboxylase in biopsies. Gastrin did not increase further, confirming that the patients had achlorhydria. Netazepide was safe and well tolerated.

CONCLUSIONS

A gastrin/cholecystokinin 2 receptor antagonist is a potential medical and targeted treatment for type 1 gastric NETs, and an alternative to regular gastroscopy or surgery. Treatment should be continuous because the tumours will regrow if it is stopped. Progress can be monitored by CgA in blood or biomarkers in mucosal biopsies.

The gastrin receptor antagonist netazepide (YF476) in patients with type 1 gastric enterochromaffin-like cell neuroendocrine tumours: review of long-term treatment

OBJECTIVE

Netazepide (YF476) is a recently developed, orally active gastrin receptor antagonist that, in short trials in patients with type 1 gastric enterochromaffin-like cell neuroendocrine tumours, has been shown to induce a significant reduction in the number and size of tumours as well as serum chromogranin A (CgA). The aim of this review is to evaluate the long-term effect and safety of netazepide.

PATIENTS AND METHODS

Five patients previously treated with netazepide in an open-label trial were offered continuous treatment with netazepide 25 mg once daily. Upper endoscopy was performed every 6 months. The tumours were counted and measured, and tissue samples were obtained from the flat corpus mucosa. Enterochromaffin-like cell hyperplasia was classified according to Solcia and colleagues and volume density of CgA immunoreactive (IR) cells was calculated. Fasting serum CgA and fasting serum gastrin were measured every 3 months.

RESULTS

All tumours regressed completely in three of five patients; time until total disappearance was 3, 9 and 12 months. In the other two patients, the number of tumours was reduced from 13 to 5 and from 14 to 3. Serum CgA showed a rapid and sustained decrease (P<0.001). The mean reduction in serum CgA was 4.1±0.5 nmol/l. Similarly, volume density of CgA IR cells in the flat corpus mucosa decreased (P<0.001), with the mean change being 2.0±0.4%. Serum gastrin and volume density of gastrin IR cells in the antral part of the stomach remained unchanged (P=0.2 and 0.7, respectively).

CONCLUSION

Long-term administration of netazepide is effective and safe.

Follow-up of patients with ECL cell-derived tumours

OBJECTIVES

To review the presentation, treatment and outcome of patients with type 1 gastric carcinoid tumours.

MATERIAL AND METHODS

We retrospectively reviewed medical records and re-evaluated histopathological specimens of 26 patients with type 1 gastric carcinoids treated at a single tertiary referral centre from 1993 to 2013, with median time of follow-up 52.5 months (IQR 90.8).

RESULTS

Seven patients (27%) had single tumours and 19 patients (73%) multiple tumours at the time of diagnosis. The median number of tumours and median diameter of largest tumour were 2.5 (IQR 3.2) and 6.0 mm (IQR 9.5) respectively. Median serum gastrin was 321.0 pmol/l (IQR 604.0) and median serum chromogranin A 7.7 nmol/l (IQR 5.3). Three patients had metastatic disease at the time of diagnosis and two developed metastases during follow-up. Patients with metastatic disease had larger primary tumours than the others (20.0 mm (IQR 28.5) vs. 5.0 mm (IQR 5.5), p = 0.04). There was a positive correlation between age and tumour size (r = 0.44, p = 0.03) and between serum chromogranin A and serum gastrin at diagnosis (r = 0.76, p = 0.001). Patients were either treated with surgery (n = 8 (31%)), a long-acting somatostatin analogue and/or gastrin receptor antagonist (n = 10 (39%)) for a period of time, or were observed without treatment (n = 8 (31%) with close endoscopic follow up.

CONCLUSIONS

Although gastric carcinoids have an overall good prognosis, a significant proportion develops metastatic disease. As partial and total gastrectomy is associated with major side effects, treatment with long-acting a somatostatin analogue or gastrin antagonist should be considered.

Subtype classification and management of gastric neuroendocrine neoplasms

Gastric neuroendocrine neoplasms (g-NENs) are a group of heterogeneous tumors arising from endocrine cells in the stomach. Because of the low incidence, clinical misdiagnosis and mismanagement of g-NENs may occasionally occur. In this review, I summarize the epidemiology, pathology, tumor staging, clinical classification, diagnostic algorithm, treatment and prognosis of g-NENs, to explain the standard diagnosis and management, as well as the latest advances in g-NEN research. The author advocates the four-type classification of g-NENs, and emphasizes that type 1 g-NENs are a recurrent disease which needs long-term follow-up. Molecular mechanism of recurrence of and medical therapy for type 1 g-NENs are the future research direction for neuroendocrine neoplasms.

A knockin mouse model for human ATP4aR703C mutation identified in familial gastric neuroendocrine tumors recapitulates the premalignant condition of the human disease and suggests new therapeutic strategies

By whole exome sequencing, we recently identified a missense mutation (p.R703C) in the human ATP4a gene, which encodes the proton pump responsible for gastric acidification. This mutation causes an aggressive familial type I gastric neuroendocrine tumor in homozygous individuals. Affected individuals show an early onset of the disease, characterized by gastric hypoacidity, hypergastrinemia, iron-deficiency anemia, gastric intestinal metaplasia and, in one case, an associated gastric adenocarcinoma. Total gastrectomy was performed as the definitive treatment in all affected individuals. We now describe the generation and characterization of a knockin mouse model for the ATP4a^R703C mutation to better understand the tumorigenesis process. Homozygous mice recapitulated most of the phenotypical alterations that were observed in human individuals, strongly suggesting that this mutation is the primary alteration responsible for disease development. Homozygous mice developed premalignant condition with severe hyperplasia, dysplasia and glandular metaplasia in the stomach. Interestingly, gastric acidification in homozygous mice, induced by treatment with 3% HCl acid in the drinking water, prevented (if treated from birth) or partially reverted (if treated during adulthood) the development of glandular metaplasia and dysplasia in the stomach and partially rescued the abnormal biochemical parameters. We therefore suggest that, in this model, achlorhydria contributes to tumorigenesis to a greater extent than hypergastrinemia. Furthermore, our mouse model represents a unique and novel tool for studying the pathologies associated with disturbances in gastric acid secretion.

Summary: Gastric pathologies in an ATP4a knockin mouse model of a mutation responsible for the development of gastric neuroendocrine tumors in humans are prevented and reverted by adding HCl to drinking water.

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

BACKGROUND

Gastric neuroendocrine tumors (GNETs) are rare and classified into three types by disease etiology and typical behavior.

METHODS

The aim was to describe outcomes after GNET resection at a single institution from 2000 to 2014, stratified by tumor type. Given the small patient number, P-values were not assigned.

RESULTS

Of 22 patients, 12 patients (55%) had Type 1, none (0%) had Type 2, and 10 (45%) had Type 3 tumors. Compared to Type 3, Type 1 patients were younger (mean age: 52 vs. 59 years) with similar rates of endoscopic resection (25% vs. 20%). Type 1 GNETs often had multiple tumors (60% vs. 10%) and were not poorly differentiated (0% vs. 11%). Only 33% of Type 1 had nodal metastases compared to 71% of Type 3. Type 1 GNETs presented with metastatic disease less often (17% vs. 40%). Three year recurrence-free survival was 33% for Type 1 compared to 86% for Type 3. Disease-specific survival at 3-years was 100% and 75% for Types 1 and 3, respectively.

CONCLUSION

Type 1 GNETs are often indolent and multifocal without nodal involvement, but have high recurrence risk. Type 3 is more aggressive with increased nodal involvement; nodal evaluation should be routinely performed. Determination of GNET type is paramount to treating patients with this rare disease. J. Surg. Oncol. 2016;114:576-580. © 2016 Wiley Periodicals, Inc.

Gastric neuroendocrine neoplasms and proton pump inhibitors: fact or coincidence?

OBJECTIVE

Reporting on three cases of gastric neuroendocrine tumors (g-NETs) in patients taking long-term proton pump inhibitors (PPIs). These tumors are not classifiable considering current criteria. g-NETs are currently grouped as: types 1 and 2, related to hypergastrinemia due to chronic atrophic gastritis and Zollinger-Ellison syndrome respectively, and type 3, normogastrinemic and more aggressive. Although the g-NETs onset in patients taking PPIs is biologically plausible, only a few cases have been reported so far.

MATERIALS AND METHODS

From January 2005 to July 2014, 31 g-NETs were referred to our Unit: 24 (77%), one (3%) and three (10%) resulted types 1, 2 and 3, respectively. Three cases (10%) did not meet the current classification criteria.

RESULTS

The three patients were administered long-term PPIs for gastro-esophageal reflux disease. Patient 1: a 78-year-old man, with a 4-mm well-differentiated g-NET (Ki-67<1%) and marked hypergastrinemia. Patient 2: a 58-year-old man affected by a 6-mm well-differentiated (Ki-67 = 4%) g-NET, with normal gastrin levels. Patients 3: a 67-year-old woman with an 18-mm well-differentiated g-NET (Ki-67 <2%), with mild hypergastrinemia. In the three patients, histology and pertinent blood tests excluded chronic atrophic gastritis, Helicobacter pylori infection or Zollinger-Ellison syndrome. The first two patients underwent endoscopic polypectomy; in the third case total gastrectomy was performed. Further clinical, endoscopic and imaging follow-up did not show any g-NET recurrence.

CONCLUSIONS

The present data point to the existence and epidemiological relevance of g-NETs associated with PPIs intake. These neoplasms are not included in the current classification, thus their treatment and follow-up have not been established.

Clinicopathological features of primary gastric neuroendocrine neoplasms: A single-center analysis

OBJECTIVE

To assess the clinical characteristics, diagnosis and therapeutic modalities for gastric neuroendocrine neoplasms (GNENs) among the Chinese population in a single institution.

METHODS

A total of 57 patients with histologically confirmed GNENs, who were diagnosed between 1995 and 2015 at the Peking Union Medical College Hospital were retrospectively reviewed. The clinical, imaging and histopathologic characteristics as well as the treatments of GNENs were collected and analyzed.

RESULTS

Patients with GNENs mostly presented with non-specific symptoms. Gastric body was the most common site of involvement. The choice of imaging modality, such as endoscopy and computed tomography depended on the tumor subtype. Chromogranin A (CgA) and synaptophysin were indispensable immunohistochemical markers for diagnosis. Significant inter-group differences in the positivity rate of CD56 were observed among the three grades (G1, G2 and G3). Therapeutic modalities included endoscopic intervention, surgical resection and pharmacotherapy, which were largely guided by the tumor subtype and the presence or absence of distant metastasis or tumor recurrence.

CONCLUSIONS

Routine endoscopic examination is recommended for the early diagnosis of GNENs. Histopathological examination can make the definite diagnosis of GNENs and clarify the nature of gastric polyps. A multidisciplinary approach is important in the management of patients with GNENs.

Clinical management of patients with gastric neuroendocrine neoplasms associated with chronic atrophic gastritis: a retrospective, multicentre study

To provide data regarding clinical presentation, pathological features, management, and response to different treatments of patients with type I gastric neuroendocrine tumors in stages 0-2A. The study design consist of an Italian multicentre, retrospective analysis of patients with type I gastric neuroendocrine tumors managed with different therapeutic approaches: surgery, endoscopic surveillance, endoscopic resection, or somatostatin analog therapy. Among the 97 patients included, 3 underwent surgery, 45 (46.4%) radical endoscopic resection of the neoplastic lesions, 13 (13.4%) follow-up with upper endoscopy, and 36 (37.1%) somatostatin analog therapy. At the end of the follow-up, all patients were alive and there was no evidence of metastatic disease. Somatostatin analog therapy resulted in a complete response in 76.0% of the patients and stable disease in 24.0%. A prolonged period of therapy, the use of a full dose of somatostatin analogs and higher gastrin levels at diagnosis were related to a complete response to the therapy. The recurrence rate was 26.3% in patients treated with somatostatin analog therapy and 26.2% in patients treated with endoscopic resection, without a statistically significant difference in terms of disease-free survival. Regarding recurrence of the disease, no statistical difference was found according to type of therapy, number of neoplastic lesions, and 2010 WHO classification. The only risk factor for tumor recurrence was a short period of medical treatment. In conclusion, our study suggested that endoscopic surveillance, endoscopic resection and somatostatin analog therapy represent valid options in the management of patients with type I gastric neuroendocrine tumors in stages 0-2A.

Recurrent gastric neuroendocrine tumors treated with total gastrectomy

Gastric neuroendocrine tumors are rare; however, the incidence has recently increased due to the increasing use of upper endoscopy. Neuroendocrine tumors arise from the excess proliferation of enterochromaffin-like (ECL) cells. The proliferative changes of enterochromaffin cells evolve through a hyperplasia-dysplasia-neoplasia sequence that is believed to underlie the pathogenesis of gastric neuroendocrine tumors. Endoscopic resection is recommended as the initial treatment if the tumor is not in an advanced stage. However, there is no definite guideline for the treatment of recurrent gastric neuroendocrine tumors following endoscopic resection. Here, we report a rare case of gastric neuroendocrine tumors in a 56-year-old male who experienced two recurrences within 11 years after endoscopic resection. The patient finally underwent a total gastrectomy. The pathological features of the resected stomach exhibited the full hyperplasia-dysplasia-neoplasia sequence of the ECL cells in a single specimen.

Intermittent treatment of recurrent type-1 gastric carcinoids with somatostatin analogues in patients with chronic autoimmune atrophic gastritis

BACKGROUND

Optimal management and treatment of type-1 gastric carcinoids is under debate.

AIMS

This prospective study evaluates the outcome of patients with recurrent type-1 gastric carcinoids treated with somatostatin analogues.

METHODS

From 2000 to 2013, among a population of 107 chronic atrophic gastritis patients, 25 (20% males, median age 62 years) developed type-1 gastric carcinoids and underwent regular clinical and endoscopic follow-up (median 77 months, range 6-165) after the initial treatment. Those patients showing recurrent disease were treated with somatostatin analogues until carcinoid disappearance.

RESULTS

12/25 patients (33% males, median age 65 years) showed recurrent gastric carcinoids and were treated with somatostatin analogues for a median duration of 12 months. Median gastrin and chromogranin A levels, which were 802 pg/mL and 33 U/L, respectively, decreased to 299 pg/mL (p=0.002) and 15.6 U/L (p=0.001) at the end of the treatment. Gastric carcinoids disappeared after a median length of treatment of 12 months. After a median time of 19.5 months from somatostatin analogues discontinuation, 4/12 patients (25% males, median age 56 years) showed a further recurrence. A new cycle of treatment was performed successfully.

CONCLUSIONS

This study confirms that type-1 gastric carcinoids are a recurring disease and somatostatin analogues, administered on 12-month cycles, represent an effective treatment.

Multicentric Type 3 Gastric Neuroendocrine Tumors

A 50-year-old woman with incidentally detected multiple gastric polyps and biopsy-proven neuroendocrine tumor (NET) was referred to our hospital. More than 10 polypoid lesions (less than 15 mm) with normal gastric mucosa were detected from the gastric body to the fundus. The serum level of gastrin was within the normal limits. There was no evidence of atrophic changes on endoscopy and serologic marker as pepsinogen I/II ratio. Computed tomography of the abdomen and pelvis revealed no evidence of metastatic lesions. She refused surgery, and we performed endoscopic polypectomy for almost all the gastric polyps that were greater than 5 mm. Although the histological examination revealed that all the removed polys were diagnosed as NET G1, three of them extended to the lateral or vertical resection margins, while two exhibited lymphovascular invasion. A follow-up upper endoscopy that was performed 6 months after the diagnosis showed multiple remnant gastric polyps that were suggestive of remnant gastric NET.

Occurrence of gastric cancer and carcinoids in atrophic gastritis during prospective long-term follow up

OBJECTIVE

Atrophic gastritis (AG) is a risk condition for gastric cancer and type I gastric carcinoids. Recent studies assessing the overall risk of gastric cancer and carcinoids in AG at long-term follow up are lacking. This study aimed to investigate in a prospective cohort of AG patients the occurrence of gastric cancer and carcinoids at long-term follow up.

METHODS

A total of 200 AG patients from a prospective cohort (67% female, median age 55 years) with a follow up of 7.5 (range: 4-23.4) years were included. Inclusion criteria were presence of AG and at least one follow-up gastroscopy with biopsies at ≥4 years after AG diagnosis. Follow-up gastroscopies at 4-year intervals were performed.

RESULTS

Overall, 22 gastric neoplastic lesions were detected (crude incidence 11%). Gastric cancer was diagnosed in four patients at a median follow up of 7.2 years (crude incidence 2%). Eleven type I gastric carcinoids were detected at a median follow up of 5.1 years (crude incidence of 5.5%). In seven patients, six low-grade and one high-grade dysplasia were found. The annual incidence rate person-year were 0.25% (95% confidence interval [CI]: 0.067-0.63%), 0.43% (95% CI: 0.17-0.89%), and 0.68% (95% CI: 0.34-1.21%) for gastric cancer, dysplasia, and type I-gastric carcinoids, respectively. The incidence rates of gastric cancer and carcinoids were not different (p = 0.07).

CONCLUSION

This study shows an annual incidence rate of 1.36% person-year for gastric neoplastic lesions in AG patients at long-term follow up. AG patients are similarly exposed to gastric cancer and type I gastric carcinoids.

Gastric cancer in patients with type I gastric carcinoids

BACKGROUND

Atrophic body gastritis (ABG) is associated with both type I gastric carcinoids (T1-GCs) and intestinal-type gastric cancer. The occurrence of gastric cancer in ABG patients with type I gastric carcinoids has not yet been described.

AIM

To describe the occurrence at follow-up of gastric cancer in ABG patients with type I gastric carcinoid in a retrospective case series in a single tertiary referral center.

METHODS

Between 1994 and 2012, 17 new cases of T1-GCs were diagnosed among a cohort of ABG patients in a single tertiary referral center for ABG. The clinical charts of these 17 T1-GC patients were retrospectively evaluated for the occurrence of gastric cancer at follow-up (median 4.2 years, range 0.5-13).

RESULTS

In 4 (23.5 %)/17 T1-GCs patients (3 females, age 40-78 years), gastric cancer occurred (median follow-up 5.9 years, range 5.1-13). Three cases were intestinal-type adenocarcinomas and one a signet-ring cell diffuse gastric cancer, localized in three cases in the antrum. In two patients, it was detected on random biopsies during follow-up gastroscopy; in the other two, gastroscopy was performed because of new symptoms. All patients with gastric cancer had associated autoimmune features (pernicious anemia, autoimmune thyroid disease and a spared antrum) compared to 77, 46 and 54 % of those without gastric cancer, although statistical significance was not reached.

CONCLUSIONS

This case series shows that in patients with T1-GCs, gastric cancer may frequently occur at long-term follow-up. Thus, these patients should be monitored by a long-term surveillance program, including an accurate bioptic sampling of the antral mucosa.

Somatostatin analogs for gastric carcinoids: For many, but not all

Gastric carcinoids (GCs) are classified as: type I, related to hypergastrinemia due to chronic atrophic gastritis (CAG), type II, associated with Zollinger-Ellison syndrome in multiple endocrine neoplasia type 1, and type III, which is normogastrinemic. The management of type-I gastric carcinoids (GC1s) is still debated, because of their relatively benign course. According to the European Neuroendocrine Tumor Society guidelines endoscopic resection is indicated whenever possible; however, it is not often feasible because of the presence of a multifocal disease, large lesions, submucosal invasion or, rarely, lymph node involvement. Therefore, somatostatin analogs (SSAs) have been proposed as treatment for GC1s in view of their antisecretive, antiproliferative and antiangiogenic effects. However, in view of the high cost of this therapy, its possible side effects and the relatively benign course of the disease, SSAs should be reserved to specific subsets of “high risk patients”, i.e., those patients with multifocal or recurrent GCs. Indeed, it is reasonable that, after the development of a gastric neuroendocrine neoplasm in patients with a chronic predisposing condition (such as CAG), other enterochromaffin-like cells can undergo neoplastic proliferation, being chronically stimulated by hypergastrinemia. Therefore, definite indications to SSAs treatment should be established in order to avoid the undertreatment or overtreatment of GCs.

Gastric neuroendocrine tumors: prevalence in Europe, USA, and Japan, and rationale for treatment with a gastrin/CCK2 receptor antagonist

OBJECTIVE

Gastric carcinoids (neuroendocrine tumors) arise from enterochromaffin-like cells in the gastric mucosa. Most are caused by hypergastrinemia. The objectives were to determine if their prevalence in Europe, USA and Japan meets the criteria for an orphan disease and to justify treatment with a gastrin/CCK2 receptor antagonist.

METHODS

We obtained data from European and USA cancer registries, and searched PubMed.

RESULTS

Prevalence per 10,000 population obtained from cancer registries was: median 0.32 (range 0.09-0.92) for Europe; and 0.17 for the USA, equivalent to 4812 for the whole population. A PubMed search for gastric carcinoids yielded prevalence for Japan only, which was 0.05 per 10,000 population, equivalent to 665 for the entire population. A further search for gastric carcinoids in patients with pernicious anemia (PA) or autoimmune chronic atrophic gastritis (CAG), two presentations of about 80% of gastric carcinoids, produced prevalence rates of 5.2-11%. Prevalence of PA itself was 0.12-1.9%. Data on CAG epidemiology were sparse.

CONCLUSION

Prevalence of gastric carcinoids varied widely. All sources probably underestimate prevalence. However, prevalence was below the limits required for recognition by drug regulatory authorities as an orphan disease: 5 per 10,000 population of Europe; 200,000 for the whole population of the USA; and 50,000 for the whole population of Japan. Because gastric carcinoids are an orphan disease, and nonclinical and healthy volunteer studies support treatment with netazepide, a gastrin/CCK2 antagonist, netazepide has been designated an orphan medicinal product in Europe and the USA for development as targeted treatment for gastric carcinoids.

Endoscopic diagnosis and management of type I neuroendocrine tumors

Type I gastric neuroendocrine tumors (TI-GNETs) are related to chronic atrophic gastritis with hypergastrinemia and enterochromaffin-like cell hyperplasia. The incidence of TI-GNETs has significantly increased, with the great majority being TI-GNETs. TI-GNETs present as small (< 10 mm) and multiple lesions endoscopically and are generally limited to the mucosa or submucosa. Narrow band imaging and high resolution magnification endoscopy may be helpful for the endoscopic diagnosis of TI-GNETs. TI-GNETs are usually histologically classified by World Health Organization criteria as G1 tumors. Therefore, TI-GNETs tend to display nearly benign behavior with a low risk of progression or metastasis. Several treatment options are currently available for these tumors, including surgical resection, endoscopic resection, and endoscopic surveillance. However, debate persists about the best management technique for TI-GNETs.

Management and disease outcome of type I gastric neuroendocrine tumors: the Mount Sinai experience

BACKGROUND AND AIM

The incidence of gastric neuroendocrine tumors (NETs) has increased tenfold since the 1970s. Our aim was to describe the clinicopathologic profile, management, and outcomes of type I gastric NETs at The Mount Sinai Hospital.

METHODS

From existing databases of the Mount Sinai Division of Gastrointestinal Pathology and the Carcinoid Cancer Foundation, we identified 56 patients with type I gastric NETs seen at The Mount Sinai Hospital from 1993 to 2012. We generated a comprehensive dataset encompassing demographic, clinical, endoscopic, and pathologic factors. Survival information was determined from medical records and the Social Security Death Index. Tumor-node-metastasis staging was conducted, and tumors were graded based on mitotic counts and Ki67 index.

RESULTS

Median NET size was 3.0 mm; 55.8 % displayed multifocal disease. Stages I, II, III, and IV disease were observed in 83.8, 10.8, 5.4, and 0 %, respectively. Tumors were either low (69.7 %) or intermediate (30.3 %) grade. Furthermore, 3.6 % of patients developed gastric dysplasia, and 5.5 % had gastric adenocarcinoma. Patients underwent endoscopy every 15 months, while 28.6 % underwent polypectomy, 32.7 % somatostatin therapy, and 46.4 % surgical resection. 5- and 10-year disease-specific survival was 100 %.

CONCLUSIONS

Most patients received annual endoscopic surveillance, with a minority undergoing surgical resection, though outcomes remained excellent independent of therapeutic approach. We identified a very low but real rate of loco-regional spread, despite the generally indolent behavior of type I gastric NETs. Several patients demonstrated concurrent dysplasia or adenocarcinoma, underscoring the efficacy of regular endoscopic management not only for gastric NETs, but also for dysplasia and adenocarcinoma.

Laparoscopic resection of gastrointestinal neuroendocrine tumors with special contribution of radionuclide imaging

The surgical treatment of neuroendocrine tumors (NETs) draws on experience and guidelines more than on prospective randomized trials. The incidence of NET is increasing in all parts of the gastrointestinal tract. A variety of classifications introduced over the last decade may have led to difficulties in judging clinical relevance and determining the right surgical strategy. The North American Neuroendocrine Tumor Society and the European Neuroendocrine Tumor Society have developed usable guidelines from the available literature. For more than 20 years laparoscopy has developed as the gold standard for various surgical indications. Nevertheless, few trials have compared open and laparoscopic surgery with regard to NET. This review summarizes the recent literature on surgery for NET and incorporates the evidence on laparoscopy for cancer which might be also applied for NET.

Current concepts in the diagnosis and management of type 1 gastric neuroendocrine neoplasms

The vast majority of gastrin-related gastrointestinal neuroendocrine neoplasms (GI-NENs) develop in the context of chronic atrophic gastritis (type 1), a condition closely related to autoimmune thyroid diseases. These neoplasms are defined as gastric NENs type 1 (GNEN1) and have recently been shown to constitute the commonest GI-NENs in a prospective study. GNEN1s are usually multiple and follow a relative indolent course, raising questions regarding the extent that such patients should be investigated and the appropriate therapeutic interventions needed. Recently, a number of consensus statements and guidelines have been published from various societies dealing with the diagnosis and management of GI-NENs. Endocrinologists are among the many different medical specialties involved in GNEN1s diagnosis and management. However, despite recent advances, few randomized trials are available, and thus existing evidence remains relatively weak compared to other malignancies. The purpose of this review is to provide recent evidence along with currently employed modalities addressing the diagnosis, management, long-term follow-up and potential comorbidities of GNEN1s.

Review article: the investigation and management of gastric neuroendocrine tumours

BACKGROUND

Gastric carcinoids (GCs) or neuroendocrine tumours (NETs) are increasingly identified at endoscopy, and account for 0.6-2% of all gastric polyps identified. The SEER database in the US has demonstrated a rising incidence of gastric NETs amongst all NETs; from 2.2% between 1950 and 1969 to 6.0% between 2000 and 2007.

AIM

To review the literature and assist clinicians in managing patients with GCs.

METHODS

A literature search was conducted through MEDLINE using search terms: gastric, carcinoid, neuroendocrine tumour, therapy, endoscopy, mucosal resection, submucosal dissection. Relevant articles were identified through manual review. The reference lists of these articles were reviewed to include further appropriate articles.

RESULTS

There are three types of GCs with important epidemiological, pathophysiological, histological and endoscopic differences that affect prognosis and management. Type 1 and 2 GCs develop in the context of hypergastrinaemia that originates from achlorhydria in atrophic gastritis and a gastrinoma, respectively. Type 3 GCs occur sporadically and independent of gastrin. The histological type, grade and Ki67 index are used to determine prognosis and direct clinical management. Type 1 GCs >1 cm in size and type 2 GCs should be assessed for invasion beyond the submucosa with EUS prior to endoscopic resection with EMR or ESD. Type 3 GCs should be managed as per recommendations for gastric adenocarcinoma. The treatment of advanced disease is multimodal.

CONCLUSIONS

Patients with gastric carcinoids should be discussed in a specialist neuroendocrine tumour multidisciplinary meeting to ensure all treatment options are explored in localised and advanced disease. Areas of controversy exist that need further research.

Management and clinical outcomes of type I gastric carcinoid patients: retrospective, multicenter study in Japan

BACKGROUND AND AIM

Type I gastric carcinoids (TIGC) are associated with chronic atrophic gastritis (CAG) with hypergastrinemia and hyperplasia of enterochromaffin-like cells. Several treatment options are currently available for these tumors including total gastrectomy, partial resection, antrectomy, endoscopic resection and endoscopic surveillance. The present study evaluated different treatment approaches and clinical outcomes of patients with TIGC in Japan.

METHODS

Between 1991 and 2011, 82 patients with TIGC were identified at multicenter institutions in Japan. Patient demographics, tumor size, depth of invasion, vessel involvement, treatment approach, Helicobacter pylori infection, serum gastrin level, recurrence-free survival (RFS) and disease-specific survival (DSS) were analyzed.

RESULTS

Median age of all patients at the time of diagnosis was 56 years (range, 24-79 years). There were 44 males and 38 females. Patients underwent endoscopic surveillance (n=25), endoscopic resection (n=41) or surgical resection (n=16). Intramucosal invasion was found in 19 patients, submucosal invasion in 44 patients and muscularis propria invasion in one patient. Tumor diameter was ≤ 10 mm in 71 patients, 11-20mm in five patients and ≥ 21 mm in five patients. None of the patients showed rapidly growing tumors, local recurrence or metastasis. The median (range) follow-up period was 7(0-20) years. RFS was 97.6% and DSS was 100% in all the patients.

CONCLUSION

The prognosis of TIGC patients treated by different modalities in Japan is favorable regardless of the generational change of management for TIGC.

Gastric carcinoid in the absence of atrophic body gastritis and with low Ki67 index: a clinical challenge

BACKGROUND

Gastric carcinoids (GCs) represent 23% of all digestive neuroendocrine tumors (NETs). They can be distinguished into three types: type I (in the presence of atrophic body gastritis, ABG), type II (in the presence of Zollinger-Ellison/multiple endocrine neoplasia type I syndrome), type III (sporadic carcinoids, without any background pathology).

AIM

To describe a case of undetermined type of GCs in an Italian referral center for NETs and its prevalence among GCs during a 6-year period.

RESULTS

In a case series of 16 GCs seen at our unit between 2007 and 2012, 14 (83.3%) patients had type I carcinoid and 1 patient (6.2%) had type III carcinoid. One patient did not accomplish to the actual classification criteria. This patient had a well-differentiated carcinoid with low Ki67, but multiple gastric biopsies performed at 3-year follow-up gastroscopies excluded the presence of ABG. The patient had fundic cystic polyps, suggesting long-term use of proton pump inhibitors, possibly associated with GCs.

CONCLUSIONS

This case shows that a GC may occur in the absence of ABG and with low Ki67 index, making classification according to actual criteria difficult. Further studies are needed to better understand the occurrence of this particular type of GCs.

Long-term results of endoscopic resection for type I gastric neuroendocrine tumors

BACKGROUND

A number of different therapies, including endoscopic resection, have been suggested for the treatment of Type 1 gastric neuroendocrine tumors (NETs). The current study aimed to determine the long-term efficacy of endoscopic resection for Type 1 gastric NETs.

METHODS

Twenty-two patients (from 1999 to 2012) with Type 1 gastric NETs were included in the study. All patients were treated with endoscopic resection and received regular followed-up appointments at a tertiary referral center.

RESULTS

All patients were initially diagnosed with hypergastrinemia, atrophic gastritis and intestinal metaplasia. Polyps' diameters were >1 cm in 4 patients, and between 0.5 and 1 cm in 18 patients. All detectable lesions were successfully resected. One patient required surgery due to gastric perforation during endoscopic mucosal resection. Recurrence was detected in four patients (18%) and endoscopic resection was performed again. Local or distant metastasis was not observed in any patient during follow-up. Median follow-up time was 7 years, with a maximum of 14 years. Seventeen patients (78%) completed a 5-year follow-up period, and overall disease-free survival rate was 100%.

CONCLUSIONS

Long-term follow-ups with 22 patients suggest that endoscopic resection of Type 1 gastric NETs is a safe and effective treatment option with a relatively low recurrence rate.

Netazepide, a gastrin receptor antagonist, normalises tumour biomarkers and causes regression of type 1 gastric neuroendocrine tumours in a nonrandomised trial of patients with chronic atrophic gastritis

INTRODUCTION

Autoimmune chronic atrophic gastritis (CAG) causes hypochlorhydria and hypergastrinaemia, which can lead to enterochromaffin-like (ECL) cell hyperplasia and gastric neuroendocrine tumours (type 1 gastric NETs). Most behave indolently, but some larger tumours metastasise. Antrectomy, which removes the source of the hypergastrinaemia, usually causes tumour regression. Non-clinical and healthy-subject studies have shown that netazepide (YF476) is a potent, highly selective and orally-active gastrin/CCK-2 receptor antagonist. Also, it is effective in animal models of ECL-cell tumours induced by hypergastrinaemia.

AIM

To assess the effect of netazepide on tumour biomarkers, number and size in patients with type I gastric NETs.

METHODS

We studied 8 patients with multiple tumours and raised circulating gastrin and chromogranin A (CgA) concentrations in an open trial of oral netazepide for 12 weeks, with follow-up 12 weeks later. At 0, 6, 12 and 24 weeks, we carried out gastroscopy, counted and measured tumours, and took biopsies to assess abundances of several ECL-cell constituents. At 0, 3, 6, 9, 12 and 24 weeks, we measured circulating gastrin and CgA and assessed safety and tolerability.

RESULTS

Netazepide was safe and well tolerated. Abundances of CgA (p<0.05), histidine decarboxylase (p<0.05) and matrix metalloproteinase-7(p<0.10) were reduced at 6 and 12 weeks, but were raised again at follow-up. Likewise, plasma CgA was reduced at 3 weeks (p<0.01), remained so until 12 weeks, but was raised again at follow-up. Tumours were fewer and the size of the largest one was smaller (p<0.05) at 12 weeks, and remained so at follow-up. Serum gastrin was unaffected.

CONCLUSION

The reduction in abundances, plasma CgA, and tumour number and size by netazepide show that type 1 NETs are gastrin-dependent tumours. Failure of netazepide to increase serum gastrin further is consistent with achlorhydria. Netazepide is a potential new treatment for type 1 NETs. Longer, controlled trials are justified.

TRIAL REGISTRATION

European Union EudraCT database 2007-002916-24 https://www.clinicaltrialsregister.eu/ctr-search/search?query=2007-002916-24ClinicalTrials.gov NCT01339169 http://clinicaltrials.gov/ct2/show/NCT01339169?term=yf476&rank=5.

Endoscopic treatment for early foregut neuroendocrine tumors

Foregut neuroendocrine tumors (NETs) include those arising in the esophagus, stomach, pancreas, and duodenum and seem to have a broad range of clinical behavior from benign to metastatic. Several factors including the advent of screening endoscopy may be related to increased incidence of gastrointestinal NETs; thus, many foregut NETs are diagnosed at an early stage. Early foregut NETs, such as those of the stomach and duodenum, can be managed with endoscopic treatment because of a low frequency of lymph node and distant metastases. However, controversy continues concerning the optimal management of early foregut NETs due to a lack of controlled prospective studies. Several issues such as indications, technical issues, and outcomes of endoscopic treatment for early foregut NETs are reviewed based on some published studies.

Endoscopic resection for gastrointestinal neuroendocrine tumors

Gastrointestinal (GI) and neuroendocrine tumors (NETs) can be treated by mini-invasive endoscopic resection when localized in the superficial layers of the bowel wall and their size is <20 mm. Endoscopic diagnosis of NETs is usually incidental or suspected after clinical, laboratory or imaging findings. Endoscopic mucosal resection is the most commonly used technique for NET removal, endoscopic submucosal dissection is indicated in selected cases, while papillectomy is feasible for ampullary lesions. Histopathologic assessment of the resection margin (circumferential and deep) is important for staging. Incidence of endoscopic mucosal resection-/endoscopic submucosal dissection-related complications for removal of GI NETs are similar to those reported for other GI lesions. Endoscopic follow-up is based on histopathologic characteristics of the resected NETs and its site. NETs >20 mm in size, with penetration of the muscle layer and/or serosa are at high risk for metastases and surgical approach is recommended when feasible.

Gastric carcinoids (neuroendocrine neoplasms)

Gastric neuroendocrine neoplasms of the stomach can be divided into the usually well-differentiated, hypergastrinemia-dependent type I and II lesions and the more aggressively behaving gastrin-independent type III lesions. Studying menin and its complex interrelationship with gastrin may provide insight into tumor biology at the clinical level and in terms of basic cell biology (eg, the role of the epigenome in neuroendocrine cell proliferation), and lead to potential consideration of other targets that are known candidates for molecular-based therapies in other adenocarcinomas.

Clinical impact of endoscopic submucosal dissection for gastric neuroendocrine tumors: a retrospective study from mainland China

As a minimally invasive technique, endoscopic resection may benefit patients diagnosed with early stage gastrointestinal neuroendocrine tumors (NETs). However, no studies have yet been published in which endoscopic submucosal dissection (ESD) has been applied for gastric NETs. For the first time a research group in China applied ESD to remove gastric NETs, and indicated that ESD should be considered for treatment of eligible gastric NETs because the technique shows a high histologically complete resection rate, provides accurate histopathological evaluation, has a low complication rate, and can be performed within a reasonable timeframe.

Current concepts on gastric carcinoid tumors

Gastric carcinoid tumors (GCs) are rare lesions representing less than 10% of carcinoid tumors and less than 1% of all stomach neoplasms. There are three distinct types of gastric carcinoids; type I includes the vast majority (70–85%) of these neoplasms that are closely linked to chronic atrophic gastritis. Type II which accounts for 5–10 %, is associated with Zollinger-Ellison syndrome and often occurs in the context of multiple endocrine neoplasia type 1. Type III, finally, represents 15–25% of gastric carcinoids and is characterized by a far more aggressive course. The optimal clinical approach to GCs remains to be elucidated, depending upon type, size, and number of carcinoids. While there is universal agreement about the surgical treatment of type III GCs, current options for type I and II include simple surveillance, endoscopic polypectomy, surgical excision associated with or without surgical antrectomy, or total gastrectomy. Moreover, the introduction of somatostatin analogues could represent another therapeutic option.

Management of gastric carcinoids (neuroendocrine neoplasms)

Gastric neuroendocrine neoplasms of the stomach can be divided into the usually well-differentiated, hypergastrinemia-dependent type I and II lesions and the more aggressively behaving gastrin-independent type III lesions. Mainly due to better diagnostics and awareness of this tumor, the observed incidence has increased more than tenfold over the last 30 years. Small (<15-20 mm) localized type I and II lesions that are slowly proliferating (Ki67<2%) can usually be managed conservatively with endoscopic surveillance. Reducing hypergastrinemia by surgical removal of an underlying gastrinoma is important in inhibiting growth and induce reduction of type II lesions, while the specific gastrin receptor antagonist YF476 or gastrin antibodies may become useful for both type I and II lesions. Infiltrating and metastasized tumors and type III lesions require a more aggressive approach with surgical resection and consideration of modalities such as somatostatin analogs, cytotoxics, and peptide receptor targeted treatment.

Gastric and duodenal neuroendocrine tumours

Gastric neuroendocrine neoplasms (NENs) are increasing in frequency and have a varied spectrum with regard to histology, clinicopathologic background, stage, and prognosis. They are usually discovered incidentally, are for the most part benign and are associated with hypergastrinaemia (secondary either to chronic atrophic gastritis or rarely Zollinger-Ellison syndrome; types 1 and 2, respectively) or more rarely sporadic type 3. Applications of recent staging and grading systems - namely using Ki-67 proliferative indices - (from ENETS and WHO 2010) can be particularly helpful in further categorising these tumours. The natural history of Type 1 gastric carcinoids is generally (>95%) favourable and simple surveillance is usually recommended for small (<1 cm) T1 tumours, with local (endoscopic or surgical) resection for larger lesions. Other potential therapies such as somatostatin analogues and gastrin receptor antagonists may offer newer therapeutic possibilities. Rarely, gastric NENs have a malignant course and this is usually confined to Type 2 and especially Type 3 tumours; the latter mimic the biological course of gastric adenocarcinoma and require radical oncological therapies. Most duodenal NENs, apart from gastrinomas (that are not dealt with here) are sporadic and non functional. They are also increasing in frequency probably due to incidental discovery at endoscopy or imaging for other reasons and this may account for their overall good prognosis. Peri-ampullary and ampullary NENs may have a more aggressive outcome and should be carefully appraised and treated (often with surgical resection).

Treatment of gastric carcinoids type 1 with the gastrin receptor antagonist netazepide (YF476) results in regression of tumours and normalisation of serum chromogranin A

BACKGROUND

Patients with chronic atrophic gastritis have long-term gastric hypoacidity, and secondary hypergastrinaemia. Some also develop gastric ECL cells carcinoids (type 1 GC). Most type 1 GC remain indolent, but some metastasise. Patients undergo surveillance, and some are treated with somatostatin analogues, endoscopic resection or surgery. Netazepide (YF476) is a highly selective, potent and orally active gastrin receptor antagonist, which has anti-tumour activity in various rodent models of gastric neoplasia driven by hypergastrinaemia. Netazepide has been studied in healthy volunteers.

AIM

To assess the effect of netazepide on type 1 GC.

METHODS

Eight patients with multiple type 1 GC received oral netazepide once daily for 12 weeks, with follow-up at 12 weeks in an open-label, pilot trial. Upper endoscopy was performed at 0, 6, 12 and 24 weeks, and carcinoids were counted and measured. Fasting serum gastrin and chromogranin A (CgA) and safety and tolerability were assessed at 0, 3, 6, 9, 12 and 24 weeks.

RESULTS

Netazepide was well tolerated. All patients had a reduction in the number and size of their largest carcinoid. CgA was reduced to normal levels at 3 weeks and remained so until 12 weeks, but had returned to pre-treatment levels at 24 weeks. Gastrin remained unchanged throughout treatment.

CONCLUSIONS

The gastrin receptor antagonist netazepide is a promising new medical treatment for type 1 gastric carcinoids, which appear to be gastrin-dependent. Controlled studies and long-term treatment are justified to find out whether netazepide treatment can eradicate type 1 gastric carcinoids.

Endoscopic submucosal dissection for foregut neuroendocrine tumors: An initial study

AIM: To evaluate the feasibility and efficacy of endoscopic submucosal dissection (ESD) for foregut neuroendocrine tumors (NETs).

METHODS: From April 2008 to December 2010, patients with confirmed histological diagnosis of foregut NETs were included. None had regional lymph node enlargement or distant metastases to the liver or lung on preoperative computerized tomography scanning or endoscopic ultrasonography (EUS). ESD was attempted under general anesthesia. After making several marking dots around the lesion, a mixture solution was injected into the submucosa. The mucosa was incised outside the marking dots. Dissection of the submucosal layer beneath the tumor was performed under direct vision to achieve complete en bloc resection of the specimen. Tumor features, clinicopathological characteristics, complete resection rate, and complications were evaluated. Foregut NETs were graded as G1, G2, or G3 on the basis of proliferative activity by mitotic count or Ki-67 index. All patients underwent regular follow-up to evaluate for any local recurrence or distant metastasis.

RESULTS: Those treated by ESD included 24 patients with 29 foregut NETs. The locations of the 29 lesions are as follows: esophagus (n = 1), cardia (n = 1), stomach (n = 23), and duodenal bulb (n = 4). All lesions were found incidentally during routine upper gastrointestinal endoscopy for other indications, and none had symptoms of carcinoid syndrome. Preoperative EUS showed that all tumors were confined to the submucosa. Among the 24 gastric lesions, 16 lesions in 11 patients were type I gastric NETs arising in chronic atrophic gastritis with hypergastrinemia, while the other 8 solitary lesions were type III because of absence of atrophic gastritis in these cases. All of the tumors were removed in an en bloc fashion. The average maximum diameter of the lesions was 9.4 mm (range: 2-30 mm), and the procedure time was 20.3 min (range: 10-45 min). According to the World Health Organization 2010 classification, histological evaluation determined that 26 lesions were NET-G1, 2 gastric lesions were NET-G2, and 1 esophageal lesion was neuroendocrine carcinoma (NEC). Complete resection was achieved in 28 lesions (28/29, 96.6%), and all of them were confined to the submucosa in histopathologic assessment with no lymphovascular invasion. The remaining patient with NEC underwent additional surgery because the resected specimens revealed angiolymphatic and muscularis invasion, as well as incomplete resection. Delayed bleeding occurred in 1 case 3 d after ESD, which was managed by endoscopic treatment. There were no procedure-related perforations. During a mean follow-up period of 24.4 mo (range: 12-48 mo), local recurrence occurred in only 1 patient 7 mo after initial ESD. This patient successfully underwent repeat ESD. Metastasis to lymph nodes or distal organs was not observed in any patient. No patients died during the study period.

CONCLUSION: ESD appears to be a safe, feasible, and effective procedure for providing accurate histopathological evaluations and curative treatment for eligible foregut NETs.

Gastric neuroendocrine tumours

BACKGROUND

Gastric neuroendocrine tumours (NETs) are increasingly recognised, and management decisions may be difficult due to an incomplete understanding of aetiology, natural history and optimum therapy. This article presents a current understanding based on recent advances in epidemiology, classification, molecular profiling, and treatment.

METHODS

Relevant medical literature was identified from searches of PubMed and references cited in appropriate articles identified. Selection of articles was based on peer review, journal and relevance.

RESULTS

Gastric NETs may be divided into three clinical prognostic groups: type I is associated with autoimmune atrophic gastritis and hypergastrinaemia, type II is associated with Zollinger-Ellison syndrome, and type III lesions are gastrin-independent, have the greatest metastatic potential and poorest prognosis. There has been an increased frequency of gastric NETs reported. Management approaches have evolved in parallel with advances in endoscopic staging and surgery, as well as improved understanding of the biology and natural history of NETs.

CONCLUSIONS

Gastric NETs present a spectrum of activity from indolent tumours to metastatic malignancy. Treatment decisions for patients must be individualised and are best managed by a multidisciplinary team approach. The current evidence base is limited to small series and efforts to treat patients within clinical networks of expertise are warranted.

Autoimmune gastritis: histology phenotype and OLGA staging

BACKGROUND

Among Western populations, the declining incidence of Helicobacter pylori infection coincides with a growing clinical impact of autoimmune gastritis.

AIMS

To describe the histological phenotype of autoimmune gastritis, also to test the prognostic impact of OLGA staging in the autoimmune setting.

METHODS

A single-institutional series (spanning the years 2003-2011) of 562 consecutive patients (M:F ratio: 1:3.7; mean age = 57.6 ± 14.4 years) with serologically confirmed autoimmune gastritis underwent histology review and OLGA staging.

RESULTS

Helicobacter pylori infection was ascertained histologically in 44/562 cases (7.8%). Forty six biopsy sets (8.2%) featured OLGA stages III-IV; they included all four cases of incidental epithelial neoplasia (three intraepithelial and one invasive; three of these four cases had concomitant H. pylori infection). There were 230 (40.9%) and 139 (24.7%) cases, respectively, of linear and micro-nodular enterochromaffin-like cell hyperplasia; 19 (3.4%) type I carcinoids were detected. The series included 116 patients who underwent repeated endoscopy/biopsy sampling (mean time elapsing between the two procedures = 54 months; range 24-108). Paired histology showed a significant (P = 0.009) trend towards a stage progression [the stage increased in 25/116 cases (22%); it remained unchanged in 87/116 cases (75%)].

CONCLUSIONS

In autoimmune gastritis, the cancer risk is restricted to high-risk gastritis stages (III-IV), and is associated mainly with concomitant H. pylori infection. OLGA staging consistently depicts the time-dependent organic progression of the autoimmune disease and provides key information for secondary gastric cancer prevention strategies.