Digestive endocrine tumors (DETs) constitute a heterogeneous group of tumors that derive from neuroendocrine cells. They are rare tumors, with an incidence of about 2 to 3 cases/100 000/year and an age of onset of around 60 years. They are slightly more common in females.
Several criteria are used to classify DETs, namely:
— their localization, as they may be observed along the whole length of the gastrointestinal tract from the esophagus to the rectum,
— whether they present functional characteristics or not, which determines the presence of symptoms,
— their degree of differentiation,
— their malignant potential
— and the possible existence of hepatic metastases that reduces the 5-year survival from 70-80% to 30-40% on average.
Currently, the WHO classification is the most widely used in Europe; it has just been modified and the 2010 version was issued recently. It associates differentiation, mitotic index and proliferation index (Ki67). A TNM classification must be added for a precise characterization of the tumor. Besides, the ENETS classification published in 2006 and 2007 combines histological grading and TNM staging. Whatever the classification used, these elements determine the prognosis, but also the type of management recommended.
This management is based primarily on surgery, symptomatic treatment, chemotherapy (CT) and local ablation techniques such as chemoembolization or metabolic radiotherapy. The strategy depends on the stage of the tumor, its differentiation, its development and its localization (duodeno-pancreatic tumors versus tumors of the gastrointestinal tract). Surgery (of the tumor or the metastases) should always be considered as the treatment of choice for differentiated tumors as it is the only potentially curative treatment available. It should be envisaged, even if only partial resection is possible, as medical treatments are more effective when tumors are smaller. However, the tumors are often diagnosed at a late stage, when they are bulky and the metastatic invasion has already commenced. Metastasis development must then be taken into account and other therapeutic options considered.