Neuroendocrine tumors (NETs) are relatively rare
tumors, mainly originating from the digestive system, able to produce bioactive
amines and
hormones. NETs tend to be slow growing and are often diagnosed when metastatic. The localization of a NETs and the assessment of the extent of disease are crucial for management. Commonly used diagnostic techniques include morphological imaging (ultrasound, computerized tomography, magnetic resonance), and functional imaging (
somatostatin receptor scintigraphy, positron emission tomography techniques). Treatment is multidisciplinary and should be individualized according to the
tumor type, burden, and symptoms. Therapeutic tools include surgery, interventional radiology, and medical treatments such as
somatostatin analogues,
interferon,
chemotherapy, new targeted drugs and
peptide receptor radionuclide therapy (PRRT) with radiolabeled
somatostatin analogues. NETs usually over-express
somatostatin receptors, thus enabling the
therapeutic use of
somatostatin analogues, one of the basic tools, able to reduce signs and symptoms of
hormone hypersecretion, improve quality of life, and slow
tumor growth. PRRT with
somatostatin analogues
90Y-DOTATOC and
177Lu-DOTATATE has been explored in NETs for more than a decade. Present knowledge and clinical studies indicate that it is possible to deliver high-absorbed doses to
tumors expressing sst2 receptors, with partial and complete objective responses in up to 30% of patients. Side effects, involving the kidney and the bone marrow, are mild if adequate renal protection is used. Moreover, a consistent survival benefit is reported. As NETs may also express
cholecystokinin 2,
bombesin,
neuropeptide Y or
vasoactive intestinal peptide receptors even simultaneously, the potential availability and biological stability of radio-analogues will improve the multireceptor targeting of NETs.