[Neuroendocrine tumors of the stomach. Risk stratification and therapy]

Spannungsfeld endoskopische Resektionsverfahren bei GEP-NET // Endoscopic resection for GEP-NET

Neuroendokrine Tumoren des Verdauungstraktes (GEP-NET) sind eine seltene Tumorentität, die häufig als Zufallsbefund diagnostiziert werden. Ein großer Teil dieser Zufallsdiagnosen wird im Rahmen einer endoskopischen Untersuchung gestellt. Während die vollständige Entfernung des Tumors im Sinne einer kurativen chirurgischen Resektion nach onkologischen Kriterien das Standardvorgehen für lokalisierte Tumorerkrankungen ist, kann bei kleinen Tumoren ohne Hinweis und Risiko für eine lymphogene Metastasierung eine endoskopische Abtragung in gleicher Intention erfolgen. Während dies für Magen-, Duodenum- und Rektum-NET der Standard ist, sollten NET des Jejunums und Ileums aufgrund der hohen Metastasierungsrate trotz geringer Tumorgröße regelhaft nicht endoskopisch angegangen werden. Die Grenze für eine endoskopische Resektion ergibt sich sowohl durch die technische Machbarkeit im Sinne des Erreichens einer R0-Resektion, der erwarteten Komplikationen im Sinne von Blutung und Perforationen als auch durch das vermutete Risiko für eine lymphogene Metastasierung. Generell wird eine endoskopische Resektion bei Befunden < 1 cm regelhaft empfohlen, da sowohl die gute technische Machbarkeit als auch das geringe Metastasierungsrisiko für eine endoskopische Resektion sprechen. Bei allen Befunden über 2 cm Größe sind sowohl die technischen Erfolgsaussichten so niedrig als auch das Metastasierungsrisiko so hoch, dass in dieser Situation regelhaft ein chirurgisches Vorgehen erfolgen sollte. Es bleibt somit ein Graubereich bei der Tumorgröße zwischen 1 und 2 cm, wo sowohl endoskopische, aber auch chirurgische Resektionsverfahren sinnvoll eingesetzt werden können. Zunehmend kommen auch gemeinsame Eingriffe im Sinne eines endoskopisch-laparoskopischen Rendezvous-Verfahrens zum Einsatz – insbesondere im Duodenum bieten sich diese Eingriffe an, um eine minimale Resektion mit größtmöglicher R0-Erfolgsrate und niedriger Perforationsrate zu erreichen.

[Neuroendocrine neoplasia of the stomach : What is new?]

INTRODUCTION

Neuroendocrine Neoplasms are classified according to the new WHO classification in (1.) well differentiated neuroendocrine tumors G1 (NET G1, Ki67 ≤ 2 or mitosis count <2) and (2.) well differentiated neuroendocrine tumors G2 (NET G2, Ki67 3-20 or mitosis count 2-20) and (3.) poorly differentiated neuroendocrine carcinomas G3 (NEC G3, Ki67 > 20 or mitosis count >20).

MATERIAL AND METHODS

In this study 310 NENs of the Ludwig-Maximilians-University in Munich were reevaluated according to the new WHO classification.

RESULTS

7% of the analyzed NENs were presented as neoplasias of the stomach. In NENs of the stomach three distinct subtypes are recognized: (1) type 1 associated with autoimmune chronic atrophic gastritis (2) type 2, associated with multiple endocrine neoplasia (MEN1) and Zollinger-Ellison Syndrom; and (3) type 3, sporadic tumors.

DISCUSSION

Precursor lesions (i. e. hyperplasia of the ECL cells) are found in patients with hypergastrinaemia (type 1 and 2). This article should provide insights into the diagnosis of NENs of the stomach with emphasis on the new international standard.

[Neoplasms of the disseminated neuroendocrine cell system of the gastrointestinal tract]

The classification of neuroendocrine neoplasms (NEN) of the gastrointestinal tract and also the pancreas is based on the World Health Organization (WHO) classification from 2010, the site-related TNM stage classification and the clinicopathological characterization. This allows a classification of NEN that is adapted to the individual patient, is of high prognostic relevance and serves the needs of an adequate treatment. This article summarizes the current knowledge on the clinical pathology of gastrointestinal NEN, in order to enable a rapid diagnostic orientation.

Rare Neoplasia of the Stomach

BACKGROUND

Gastric adenocarcinoma accounts for more than 90% of malignant lesions of the stomach. Besides this entity, numerous neoplastic lesions with malignant or benign characteristics as well as lesions with uncertain malignant potential occur. This review gives an overview on rare neoplasia of the stomach, focusing on gastric polyps, gastrointestinal stromal tumors, gastric lymphoma and neuroendocrine neoplasia.

SUMMARY

A broad spectrum of rare neoplastic lesions of the stomach with significant differences in malignant potential and with specific demands of interventional therapy is known. In addition to the use of high-definition endoscopy techniques, the histopathological assessment of lesions and of the surrounding mucosa is mandatory to characterize and differentiate malignant and benign tumors.

KEY MESSAGE

Rare neoplasia of the stomach is detected in approximately 6% of patients undergoing esophagogastroduodenoscopy. Diligent examination of the gastric mucosa remains essential to detect mucosal and submucosal lesions.

PRACTICAL IMPLICATIONS

Presenting with a broad spectrum of symptoms, ranging from unspecific abdominal discomfort to gastrointestinal bleeding or symptoms of gastric outlet obstruction, different rare neoplastic lesions of the stomach with demand of specific diagnostic and therapeutic work-up occur. Diligent endoscopic evaluation of the entire gastric mucosa, preferably by high-definition endoscopy techniques, is essential in addition to histopathological examination of lesional and surrounding tissue.

GEP-NETS update: a review on surgery of gastro-entero-pancreatic neuroendocrine tumors

The incidence of neuroendocrine tumors (NETs) has increased in the last decades. Surgical treatment encompasses a panel of approaches ranging from conservative procedures to extended surgical resection. Tumor size and localization usually represent the main drivers in the choice of the most appropriate surgical resection. In the presence of small (<2 cm) and asymptomatic nonfunctioning NETs, a conservative treatment is usually recommended. For localized NETs measuring above 2 cm, surgical resection represents the cornerstone in the management of these tumors. As they are relatively biologically indolent, an extended resection is often justified also in the presence of advanced NETs. Surgical options for NET liver metastases range from limited resection up to liver transplantation. Surgical choices for metastatic NETs need to consider the extent of disease, the grade of tumor, and the presence of extra-abdominal disease. Any surgical procedures should always be balanced with the benefit of survival or relieving symptoms and patients' comorbidities.

[Gastric neuroendocrine tumors. Endoscopic and surgical treatment]

Neuroendocrine tumors (NETs) of the stomach are the most frequent among all neuroendocrine neoplasms in the digestive tract. The diagnosis and classification are complicated by the fact that these tumors have to be categorized not only by common staging and grading but also according to their pathophysiological background (types). The types differ in their biological behaviour (aggressiveness) which influences therapeutic concepts. This article explains and summarizes the etiology and classification of gastric NETs and offers a precise concept for diagnosis and treatment to improve clinical outcome.

Surgical treatment of gastrointestinal neuroendocrine tumors

INTRODUCTION

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are uncommon but clinically challenging and fascinating tumors. GEP-NETs present as either functional or as nonfunctional tumors. Functional tumors are commonly associated with a specific hormonal syndrome directly related to a hormone secreted by the tumor, like gastrinomas with a Zollinger-Ellison syndrome or carcinoid syndrome in patients with neuroendocrine tumors (NET) of the ileum. Nonfunctional tumors do not secrete a hormone resulting in a clinical syndrome.

METHODS

The natural course of GEP-NETs is highly variable. Small, benign neoplasms such as 90% of all insulinomas or gastric endocrine tumors type 1 are readily curable by surgical resection; however, most other GEP-NETs have a much less favorable prognosis. Patients with completely resected tumors generally have a good prognosis, and an aggressive surgical approach in patients with advanced disease may also prolong survival.

CONCLUSIONS

This review focuses on the current standards of surgical treatment of gastric endocrine tumors, NETs of the pancreas (PNET) and NETs of the ileum. Although the evidence level is low in many instances due to the lack of randomized controlled trials, important treatment recommendations can be given.