Guideline sources The following summarized guidelines for the evaluation and management of small bowel neuroendocrine tumors (SBNET) are prepared by our editorial team based on guidelines from the North American Neuroendocrine Tumor Society (NANETS 2017). 1 Calculator Calculator TNM classification for duodenal TNM classification for jejunoileal Guidelines 1. Diagnostic investigations Diagnostic imaging: obtain CT or MRI for the diagnosis, staging, and follow-up of patients with small bowel NETs. E Show 4 more https://web.pathway.md/diseases/recRSczWCUuC40bSE 1/3 6/24/23, 3:14 PM Small bowel neuroendocrine tumors Pathway 2. Diagnostic procedures Small bowel endoscopy: consider performing video capsule endoscopy and double balloon enteroscopy in patients with unknown primary lesions, if the preoperative diagnosis is essential for referral for surgical management. E 3. Medical management Systemic therapy: offer systemic therapy as first-line therapy in patients with poorly differentiated, high-grade small bowel NETs. E Show 3 more Management of carcinoid crisis: insufficient evidence to support the routine use of octreotide either preoperatively or preprocedurally, during the procedure itself either as an IV bolus or infusion, or weaning it perioperatively for the prevention of carcinoid crisis. I Show 3 more 4. Surgical interventions Surgical exploration: perform surgical exploration in patients with metastatic gastroenteropancreatic NETs/carcinomas and undiagnosed primaries, as most of them will have small bowel NETs after imaging. E Resection of primary tumor (indications): Consider performing resection in patients with limited well-differentiated small bowel NETs with high-grade features (Ki-67 > 20%), given the limited options for systemic treatments and the lack of knowledge regarding their natural history. E Consider performing resection of primary small bowel NETs in selected patients with metastatic disease, if feasible, to relieve existing symptoms and avoid future symptoms, and for its potential survival advantage. Take into account other factors, such as the patient's performance status and degree of liver replacement, with higher levels (> 50-70%) being associated with shorter survival and higher risk of significant postoperative liver dysfunction. E Resection of primary tumor (technical considerations): recognize that asymptomatic patients generally have a long survival without intervention, with or without somatostatin analogs or additional medical therapies, therefore surgical procedures must be performed with minimal mortality and morbidity. E Show 5 more Lymph node dissection: remove regional lymph nodes with segmental bowel resection in patients with small bowel NETs, including resection up to the origin of the segmental vascular branches from the superior mesenteric artery/superior mesenteric vein in most patients. E Show 4 more Resection of metastases (peritoneal): https://web.pathway.md/diseases/recRSczWCUuC40bSE 2/3 6/24/23, 3:14 PM Small bowel neuroendocrine tumors Pathway Remove as much disease as possible while minimizing risks in patients with peritoneal metastases. Consider resecting limited areas of seeding with the underlying peritoneum or diaphragm. Use electrocautery or argon beam for smaller lesions. E Insufficient evidence to recommend hyperthermic intraperitoneal chemotherapy as an adjunct to local treatments in patients with intraperitoneal metastases from small bowel NETs. I Resection of metastases (hepatic): attempt cytoreductive surgery in patients with NET liver metastases to improve control of hormonal symptoms and survival. Recognize that 5-year survival rates range between 60-90% with no difference regardless of whether an R0, R1, or R2 resection is achieved. E Show 5 more Prophylactic cholecystectomy: recognize that patients receiving prolonged treatment with somatostatin analogs are at high risk of gallstone formation, and previous cytoreductive procedures may complicate future laparoscopic cholecystectomy. E Show 3 more Liver transplantation: consider offering liver transplantation, although controversial, in selected patients meeting the Milan and ENETS criteria. E 5. Specific circumstances Patients with liver metastases and unknown primaries: obtain thin-slice multiphase CT of the abdomen, pelvis, and chest to evaluate the bronchi, thymus, stomach, duodenum, colorectum, appendix, pancreas, and small bowel with its mesentery for the staging of patients with NET liver metastases and unknown primaries. E Show 3 more References 1. James R Howe, Kenneth Cardona, Douglas L Fraker et al. The Surgical Management of Small Bowel Neuroendocrine Tumors: Consensus Guidelines of the North American Neuroendocrine Tumor Society. Pancreas. 2017 Jul;46 6 715 731. Open 2. M Pavel, K berg, M Falconi et al. Gastroenteropancreatic neuroendocrine neoplasms: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Ann Oncol. 2020 Jul;31 7 844 860. Open https://web.pathway.md/diseases/recRSczWCUuC40bSE 3/3