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Despite efforts from various endoscopy societies, reporting in the field of endoscopy remains extremely heterogeneous. Harmonisation of clinical practice in endoscopy has been highlighted by application of many clinical practice guidelines and standards pertaining to the endoscopic procedures and reporting are underlined. The aim of the proposed "standardised reporting" is to (1) facilitate recognition of gastrointestinal neuroendocrine neoplasms (NEN) on initial endoscopy, (2) to enable interdisciplinary decision making for treatment by a multidisciplinary team, (3) to provide a basis for a standardised endoscopic follow-up which allows detection of recurrence or progression reliably, (4) to make endoscopic reports on NEN comparable between different units, and (5) to allow research collaboration between NEN centres in terms of consistency of their endoscopic data. The ultimate goal is to improve disease management, patient outcome and reduce the diagnostic burden on the side of the patient by ensuring the highest possible diagnostic accuracy and validity of endoscopic exams and possibly interventions.

Gastroenteropancreatic (GEP) neuroendocrine neoplasms (NEN) are classified based on morphology and graded based on their proliferation rate as either well-differentiated low-grade (G1 to G2) neuroendocrine tumors (NET) or poorly differentiated high-grade (G3) neuroendocrine carcinomas (NEC). Recently, a new subgroup of well-differentiated high-grade pancreatic tumors (NET G3) has been defined. The GEP NEN G3 group consisting of both NEC and NET G3 has recently been shown to be a quite heterogeneous patient group concerning prognosis and treatment benefit, depending on factors such as the primary tumor site, differentiation, proliferation rate, and molecular alterations. In this review we discuss the existing data on diagnostics, treatment, and biomarkers in this patient group, the unmet needs, and the future perspectives.

The subject of colorectal neuroendocrine neoplasms (NENs), subdivided into well-differentiated NENs, termed neuroendocrine tumours (NETs; grade (G) 1 and 2), and poorly differentiated NENs, termed neuroendocrine carcinomas (NECs; G3) according to the 2010 World Health Organisation (WHO) classification, has arguably not had as much attention or study as NENs occurring in other sites. Colorectal NETs and NECs are however easier to study than many others since they are usually not difficult to remove and are increasingly detected because of intensified colorectal cancer screening and surveillance programmes. Colorectal NETs and NECs show site-specific heterogeneity with variable behaviour and different therapeutic options; these various aspects provide unique challenges. Because of bowel cancer screening programmes, colorectal NENs, like conventional adenocarcinomas, may be diagnosed at a stage that is associated with improved survival. In this article we intend to describe and define areas of unmet needs relating to the epidemiology, classification, pathology, diagnosis and therapy of colorectal NETs (including NETs G3), colorectal NECs, and finally, mixed adeno-neuroendocrine carcinomas (MANECs) by reviewing and discussing the relevant literature.

Contrast-enhanced computed tomography (CT) of the neck-thorax-abdomen and pelvis, including 3-phase examination of the liver, constitutes the basic imaging for primary neuroendocrine tumor (NET) diagnosis, staging, surveillance, and therapy monitoring. CT characterization of lymph nodes is difficult because of inadequate size criteria (short axis diameter), and bone metastases are often missed. Contrast-enhanced magnetic resonance imaging (MRI) including diffusion-weighted imaging is preferred for the examination of the liver, pancreas, brain and bone. MRI may miss small lung metastases. MRI is less well suited than CT for the examination of extended body areas because of the longer examination procedure. Ultrasonography (US) frequently provides the initial diagnosis of liver metastases and contrast-enhanced US is excellent to characterize liver lesions that remain equivocal on CT/MRI. US is the method of choice to guide the biopsy needle for the histopathological NET diagnosis. US cannot visualize thoracic NET lesions for which CT-guided biopsy therefore is used. Endocopic US is the most sensitive method to diagnose pancreatic NETs, and additionally allows for biopsy. Intraoperative US facilitates lesion detection in the pancreas and liver. Somatostatin receptor imaging should be a part of the tumor staging, preoperative imaging and restaging, for which 68Ga-DOTA-somatostatin analog PET/CT is recommended, which is vastly superior to somatostatin receptor scintigraphy, and facilitates the diagnosis of most types of NET lesions, for example lymph node metastases, bone metastases, liver metastases, peritoneal lesions, and primary small intestinal NETs. 18FDG-PET/CT is better suited for G3 and high G2 NETs, which generally have higher glucose metabolism and less somatostatin receptor expression than low-grade NETs, and additionally provides prognostic information.

The subject of colorectal neuroendocrine neoplasms (NENs), subdivided into well-differentiated NENs, termed neuroendocrine tumours (NETs; grade (G) 1 and 2), and poorly differentiated NENs, termed neuroendocrine carcinomas (NECs; G3) according to the 2010 World Health Organisation (WHO) classification, has arguably not had as much attention or study as NENs occurring in other sites. Colorectal NETs and NECs are however easier to study than many others since they are usually not difficult to remove and are increasingly detected because of intensified colorectal cancer screening and surveillance programmes. Colorectal NETs and NECs show site-specific heterogeneity with variable behaviour and different therapeutic options; these various aspects provide unique challenges. Because of bowel cancer screening programmes, colorectal NENs, like conventional adenocarcinomas, may be diagnosed at a stage that is associated with improved survival. In this article we intend to describe and define areas of unmet needs relating to the epidemiology, classification, pathology, diagnosis and therapy of colorectal NETs (including NETs G3), colorectal NECs, and finally, mixed adeno-neuroendocrine carcinomas (MANECs) by reviewing and discussing the relevant literature.

ZusammenfassungNeuroendokrine Neoplasien (NEN) umfassen eine seltene Tumorentität mit heterogener Biologie, Prognose und therapeutischen Optionen. In Zusammenhang mit der kürzlichen Publikation der ersten deutschen Leitlinie zur Diagnostik und Therapie von NEN erfolgte die Analyse der Kohorte des Deutschen NET-Registers der Deutschen Gesellschaft für Endokrinologie (DGE). Hierzu wurden 2686 Fälle extrahiert und ihre Patientencharakteristika wie Alter, Geschlecht, Primärtumorlokalisation, Grading und Staging dargestellt sowie das Gesamtüberleben berechnet. Zusätzlich wurden die systemischen Behandlungsstrategien in den beiden größten Untergruppen, NEN des Dünndarms und Pankreas, im Stadium der Metastasierung analysiert.Die Verteilung der Primärtumoren, die histopathologische Charakterisierung, das Tumorstadium sowie das Gesamtüberleben waren vergleichbar mit den Ergebnissen internationaler Registerstudien. Somatostatinanaloga (SSA) und die Peptid-Rezeptor-Radionuklid-Therapie (PRRT) waren die häufigsten systemischen Therapieverfahren bei Dünndarm-NEN. Hingegen wurde eine Chemotherapie – in Übereinstimmung mit der neuen Leitlinie – vor allem bei pankreatischen NEN eingesetzt und kam in der Erstlinie in ähnlicher Frequenz wie die SSA-Therapie bzw. in der Zweitlinie ähnlich häufig wie eine PRRT zum Einsatz. Prognostisch relevante Parameter waren die WHO-Klassifikation 2010 und das TNM-Staging.Die aktuelle Analyse des deutschen NET-Registers charakterisiert damit eine multizentrische, interdisziplinäre, deutschlandweite Kohorte von NEN-Patienten und beschreibt die angewendeten systemischen Therapieverfahren, das Gesamtüberleben und die prognostische Bedeutung der WHO-Klassifikation 2010 sowie des TNM-Stadiums.