Classification

• All NETs, even well-differentiated, are considered to have malignant potential!
• Pancreatic NETs can be functional - e.g. insulinoma, gastrinoma, glucagonoma, VIPoma

Carcinoid syndrome

• Primarily a/w metastatic tumors from the midgut/small intestine. Vasoactive hormones (like serotonin) produced by primary intestinal tumor are inactivated in the portal circulation/liver - thus, symptomatic carcinoid syndrome must be from tumor downstream, e.g. liver mets
• Symptoms - flushing, diarrhea
• Can also get right-sided heart disease (serotonin metabolized in lungs) - thickening of R heart valves. Recommend echo prior to surgery
• Labs:
• 24-hour urinary excretion of 5-HIAA (serotonin metabolite) - > 90% Sp/sens
• Chromogranin A
• Serum serotonin is less s/s
• Imaging: Most carcinoid tumors are highly vascular
• Management: 

• If resectable - resect, including for resectable liver metastases
• Majority of patients will recur
• Carcinoid crisis can occur intra-op with manipulation of tumor causing massive release of hormones - can cause variation in blood pressure. Can prevent by giving octreotide 200 mcg IV pre-op, +/- octreotide gtt 50-100 mcg/hr during surgery.
• If unresectable, symptomatic - medical therapy with somatostatin analogue (control symptoms and tumor growth)
• Octreotide 200 mcg subq q8h, when outpatient transition to octreotide LAR (Sandostatin) 20 - 30 mg IM q month
• Side effects include nausea; if IV can infuse over longer period of time (e.g. 30 min instead of 15 min) to minimize sfx
• If unresectable, asymptomatic - somatostatin analogue depending on tumor burden?
• Other therapies
• PRRT - peptide receptor radioligand therapy, if somatostatin-receptor positive tumor
• ? everolimus