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

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.

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.

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%.

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.