[Digestive neuroendocrine tumors]

Digestive neuroendocrine tumors (NETs) are a group of rare tumors with increasing incidence. Pathological analysis is critical to establish the diagnosis and evaluate tumor grade that relies on differentiation and proliferation index. NETs are mostly diagnosed at an advanced stage because of late occurrence of nonspecific symptoms, and can be associated with hormone hypersecretion. Chromogranin A is the main biochemical marker of NETs. Extension workup relies on conventional imaging (CT-scan, MRI) and isotopic imaging including somatostatin-receptor scintigraphy, which should be soon replaced by positron-emitting scintigraphy. The main prognostic factors include tumor stage, metastatic volume, histological differentiation and grade. Hormonal syndromes and poorly differentiated tumors are the two therapeutic emergencies. The treatment of localized well-differentiated tumors relies on endoscopic or surgical resection depending on the location and aggressiveness. Surgical removal is the only potentially curative treatment of metastatic NETs but is rarely feasible and is associated with almost constant relapse. Other antitumor therapies include somatostatin analogs, systemic chemotherapy, liver trans-arterial chemo-embolization, targeted therapies and peptide-receptor radionuclide therapy. Management strategy relies on primary tumor location, tumor aggressiveness, metastatic volume and the presence of extra-hepatic metastases. It must take into account the risk of cumulated toxicity in patients whose survival is often prolonged.