Neuroendocrine TumorsCarcinoma, Islet CellOctreotideCarcinoma, NeuroendocrinePancreatic NeoplasmsLiver NeoplasmsGastrointestinal NeoplasmsCarcinoid TumorChromogranin ANeurosecretory SystemsTreatment OutcomeReceptors, SomatostatinNeuroendocrine CellsDigestive System NeoplasmsChromograninsIntestinal NeoplasmsSomatostatinIleal NeoplasmsTumor Markers, BiologicalVipomaGastrinomaEndocrine Gland NeoplasmsGlucagonomaBronchial NeoplasmsRadiopharmaceuticals