Indications for Surgical Resection in Low-Grade Pancreatic Neuroendocrine Tumors

The role of surgical resection in low-grade pancreatic neuroendocrine tumors (P-NET) is unclear. The patients diagnosed with low-grade P-NET from 1988 to 2012 were identified in SEER. Five hundred and sixty-one patients met the inclusion criteria. A majority were white (82.9%), and node negative (69.9%). Univariate analysis revealed that tumor size (<2 cm 8.3%, 2-4 cm 38.5%, and >4 cm 40.3%; P < 0.0001) and surgery (30.9% vs 25.3%; P = 0.0014) were associated with the risk of lymph node metastases (LNM). In contrast, age (P = 0.8360), gender (P = 0.4903), and race (P = 0.4235) were not. Five-year disease-free survival was associated with size (<2 cm 89.4%, 2-4 cm 80.0%, and >4 cm 74.5%; P = 0.0089), LNM (72.4% vs 82.9%; P = 0.0025), and surgery (84.3% vs 47.5%; P < 0.0001). Cox regression model showed that the association with LNM (P = 0.0025) and surgery (P < 0.0001) was significant. Surgery was associated with an improved disease-free survival for tumors >2 cm (2-4 cm, 84.4% vs 26.0% at five years; P = 0.0003, and >4 cm, 80.5% vs 49.5% at five years; P < 0.0001) but not for those with tumor size <2 cm (P = 0.4525). In conclusions, low-grade P-NETs in patients with tumor size >2 cm showed an increased risk of LNM and improved survival with resection.