Current standards in the surgical treatment of pancreatic and small intestinal neuroendocrine tumors

Pancreatic and small intestinal neuroendocrine tumors comprise relatively rare and distinctly heterogenous tumor entities which need to be managed quite differently depending on their location, the local and distant tumor extent, hormonal activity, size, and proliferative activity. The best treatment strategy for each subgroup is controversial since evidence from prospective randomized controlled trials is lacking and treatment guidelines are mainly based on results from retrospective studies. Patients with resectable pancreatic neuroendocrine tumors (pNETs) are generally potential candidates for surgical resection, especially in case of functional pNETs. However, in patients with small asymptomatic pNETs not exceeding 2 cm in size current guidelines recommend active surveillance as an alternative to primary resection. Timing of surgery (primary resection versus watchful waiting) as well as the most beneficial surgical approach (open versus minimally invasive procedures, parenchyma-sparing versus formal resections) need to be further investigated in future clinical trials considering the different patient subgroups with regard to tumor biology and prognosis. Due to the heterogeneity of enteropancreatic NETs and the challenges of pancreatic surgery, affected patients should be treated by an interdisciplinary team of surgical and oncological experts in specialized centers. This review article summarizes the current literature on the surgical and oncological treatment of pNETs and small intestinal NETs (siNETs) with a special focus on sporadic and well-differentiated tumors.