Reviews in Endocrine and Metabolic Disorders

, Volume 18, Issue 4, pp 393–410 | Cite as

Hormone secreting gastro-entero-pancreatic neuroendocrine neoplasias (GEP-NEN): When to consider, how to diagnose?

  • Christian Fottner
  • Martina Ferrata
  • Matthias M. Weber


Neuroendocrine neoplasms of the digestive system (GEP-NEN) represent a heterogeneous group of malignancies with various clinical presentation and prognosis. GEP-NENs can potentially affect all organs of the gastrointestinal tract; characteristically they share the biological property to produce and secrete peptides and neuroamines. About 30% of GEP-NENs are hormonally active and can cause specific clinical syndromes. The clinical presentation mainly depends on the primary site of the tumor and its functionality. Because of the wide spectrum of clinical symptoms and their misperceived rarity, diagnosis of GEP-NENs is often delayed for years and tumors are detected first in an advanced stage. Early identification of a specific hormonal syndrome can significantly impact tumor diagnosis and treatment, moreover the preoperative management of NEN hormonal release avoids potential life threatening hormonal crisis. However, GEP-NEN diagnostic work-up is challenging, it requires a multidisciplinary team and needs particular experience; standardized protocols and clinical experience are essential for a proper endocrine diagnostic work-up. In addition to the biochemical diagnostic, further radiologic and endoscopic imaging modalities are required moreover, somatostatin-receptor based functional imaging, using either Octreotide-scintigraphy or novel PET-based techniques with specific isotopes like Ga68-DOTA-octreotate, plays an important role for the detection of the primary tumor as well as for the evaluation of the tumor extent.


Neuroendocrine neoplasm Gastroenteropancreatic GEP NEN Hormonally active Functional Syndrome Carcinoid Gastrinoma Zollinger ellison Insulinoma Whipple´s triad VIP Ectopic ACTH 


Compliance with ethical standards

Conflict of interest

CF and MMW received financial sponsorship for congress attendences and lectures from Novartis, Ipsen and Pfizer. MMW received unrestricted research grants by Novartis and Ipsen.


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© Springer Science+Business Media, LLC, part of Springer Nature 2017

Authors and Affiliations

  • Christian Fottner
    • 1
  • Martina Ferrata
    • 1
    • 2
  • Matthias M. Weber
    • 1
  1. 1.Schwerpunkt Endokrinologie und Stoffwechselerkrankungen, I. Medizinischen Klinik und Poliklinik; ENETS center of excellenceUniversitätsmedizin der Johannes Gutenberg-Universität MainzMainzGermany
  2. 2.Department of Medicine-DIMEDUniversity of PadovaPadovaItaly

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