Management of small asymptomatic nonfunctioning pancreatic neuroendocrine tumors: Limitations to apply guidelines into real life

Background: International guidelines suggest a watchful strategy for small nonfunctioning pancreatic neuroendocrine tumors. The aim of this study was to evaluate the management and indications for surgery in patients with asymptomatic nonfunctioning pancreatic neuroendocrine tumors ≤2 cm. Methods: Patients with asymptomatic, incidental, sporadic nonfunctioning pancreatic neuroendocrine tumors ≤2 cm without nodal or distant metastases were included (2012–2016). A comparison between active surveillance and surgery groups was performed. Results: Of the 101 included patients, 72% underwent active surveillanc and 28% were surgically treated. Patients submitted to surgery were significantly younger (53 vs 60 years, P =.013), had a higher incidence of positive 18F-fluorodeoxyglucose positron emission tomography (18% vs 50%, P =.003), and a higher incidence of cytologically determined G2 tumor (0% vs 14%, P =.008). Conservatively managed patients had a significantly smaller tumor size (12 vs 16 mm, P =.0001). The main reasons determining surgical choice were as follows: patient's preference (32%), positive 18F-fluorodeoxyglucose positron emission tomography (21.5%), main pancreatic duct dilation (17.5%), cytologically determined G2 tumor (14.5%), and young age (14.5%). At a median follow-up of 40 months, all of the 73 patients conservatively managed were alive, with no evidence of distant metastases and none underwent surgery. Only 5 patients had a tumor growth >20%. Conclusion: One-third of patients with asymptomatic small nonfunctioning pancreatic neuroendocrine tumors ≤2 cm underwent surgery. Patient's preference, initial tumor size, and young age were the main determinants of surgical indication. Preoperative diagnostic workup, including 18F-fluorodeoxyglucose positron emission tomography and cytologic grading, seems to be poorly accurate in determining malignant features in these small lesions.