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Many current guidelines recommend nonoperative management for pancreatic neuroendocrine tumors2 cm. The objective of this study was to evaluate the utilization and outcomes of resection for these pancreatic neuroendocrine tumors in the United States.Using the National Cancer Database (2004-2014), 3,243 cases of T1 (≤2.0 cm) pancreatic neuroendocrine tumors were identified. Additional patient and tumor characteristics were examined. Multivariate models were used to identify factors that predicted resection and to assess patient survival after resection.75% of pancreatic neuroendocrine tumors measuring 0 to 1.0 cm and 80% of pancreatic neuroendocrine tumors measuring1.0 and ≤2.0 cm were resected. Eighty-four pancreatic neuroendocrine tumors were functional, of which 82% were resected. Variables influencing resection included positive lymph nodes, tumor in body or tail of pancreas, well or moderately differentiated tumors, and resection at academic medical centers (odds ratio 1.5-4.9). When controlling for other variables, patients with pancreatic neuroendocrine tumors 1 to 2 cm who underwent resection had a prolonged 5-year survival rate (hazard ratio 0.51, confidence interval 0.34-0.75) when compared with those who did not undergo resection. This survival benefit of resection was not found for pancreatic neuroendocrine tumors 0 to 1 cm (hazard ratio = 0.63, confidence interval 0.36-1.11).Contrary to many current recommendations, most patients with pancreatic neuroendocrine tumors ≤2.0 cm undergo surgical resection in the United States. A survival benefit was found for resection of pancreatic neuroendocrine tumors 1 to 2 cm, suggesting that current recommendations should perhaps be revised.

Background After portal vein ligation of 1 side of the liver, the other side regenerates at a slow rate. This slow growth may be accelerated to rapid growth by adding a transection between the 2 sides, i.e., performing portal vein ligation and parenchymal transection. We found that in patients undergoing portal vein ligation and parenchymal transection, portal vein hyperflow in the regenerating liver causes a significant reduction of arterial flow due to the hepatic arterial buffer response. We postulated that the reduction of arterial flow induces hypoxia in the regenerating liver and used a rat model to assess hypoxia and its impact on kinetic growth. Methods A rat model of rapid (portal vein ligation and parenchymal transection) and slow regeneration (portal vein ligation) was established. Portal vein flow and pressure data were collected. Liver regeneration was assessed in rats using computed tomography, proliferation with Ki-67, and hypoxia with pimonidazole and HIF-1α staining. Results The rat model confirmed acceleration of regeneration in portal vein ligation and parenchymal transection as well as the portal vein hyperflow seen in patients. Additionally, tissue hypoxia was observed after portal vein ligation and parenchymal transection, while little hypoxia staining was detected after portal vein ligation. To determine if hypoxia is a consequence or an inciting stimulus of rapid liver regeneration, we used a prolyl-hydroxylase blocker to activate hypoxia signaling pathways in the slow model. This clearly accelerated slow to rapid liver regeneration. Inversely, abrogation of hypoxia led to a blunting of rapid growth to slow growth. The topical application of prolyl-hydroxylase inhibitors on livers in rats induced spontaneous areas of regeneration. Conclusion This study shows that pharmacologically induced hypoxic signaling accelerates liver regeneration similar to portal vein ligation and parenchymal transection. Hypoxia is likely an accelerator of liver regeneration. Also, prolyl-hydroxylase inhibitors may be used to enhance liver regeneration pharmaceutically.

Patients with gastroenteropancreatic neuroendocrine tumors often present with stage IV disease. Primary tumor resection in these patients remains controversial. Herein, we studied the impact of primary tumor removal, identified variables associated with prolonged survival for each neuroendocrine tumor subtype, and determined factors that influence surgeons to perform primary tumor resection.Patients with metastatic gastroenteropancreatic neuroendocrine tumors diagnosed from 2004 to 2014 were identified from the National Cancer Database. Nested Cox proportional hazards and logistic regression models were used to assess variables associated with survival and primary resection.A total of 14,510 patients met inclusion criteria. On multivariable analysis, resection of the primary tumor and grade 1 or 2 tumors was associated with prolonged survival in all subtypes (P.001). Organ-specific variables associated with prolonged survival in patients undergoing primary tumor resection included the following: low grade for all organs; young age for pancreatic, small intestinal, colonic, and rectal neuroendocrine tumor; tumor size for colonic and rectal neuroendocrine tumor; and tumor location for colonic neuroendocrine tumor. Low tumor grade was found to be significantly associated with removal of the primary tumor across all organs.This study is the first suggesting that primary tumor resection is associated with prolonged survival for all gastro-entero-pancreatic NETs. Additional variables related to survival for each NET subtype were identified and might help select patients who benefit from primary tumor removal.