Clinical presentation and outcome of nonfunctional pancreatic neuroendocrine tumors in a modern cohort

Background The natural history of nonfunctional pancreatic neuroendocrine tumors (NF-PNETs) is largely unstudied due to its rarity. The primary goal of this study was to characterize clinical features and outcomes of incidental NF-PNETs. Methods An institutional review board–approved retrospective study of patients with NF-PNET evaluated by the Surgical Oncology of University of Nebraska Medical Center was performed. Patients were evaluated with dedicated pancreatic and liver imaging using multiphasic computed tomographic scan and dedicated magnetic resonance imaging protocols. Results Forty-six patients (male, 47.8%) were evaluated, and 35 ultimately resected. Of these, 16 tumors were discovered incidentally. The median age was 62 and 59 years in incidental and symptomatically discovered, respectively. Incidental median size was 2.4 cm vs 6 cm in the symptomatic group, with a P value of .037. The presence of lymphatic and liver metastases was 10% and 25% incidental and 45% and 67% for those with symptoms (lymphatic involvement, P = .05; liver metastases P = .07). Median overall survival was 45 and 76 months ( P = .03). Conclusions Incidentally discovered NF-PNETs represent a malignancy with more questions than answers. Our series indicates that these cancers are more indolent than previously believed.