Prognosis of sporadic resected small (≤ 2 cm) nonfunctional pancreatic neuroendocrine tumors - a multi-institutional study

Abstract

Background: Non-functional pancreatic neuroendocrine tumors (NF-PNET) are rare tumors increasingly being diagnosed incidentally. Choice of treatment for small (2cm or less) NF-PNETs is difficult as their malignant potential is difficult to predict. This is reflected in the current recommendations - some favor surgery, while others suggest wait-and-see policy [1–6]. As these tumors are rare, previous clinical series are small. The aim of this study was to identify factors affecting prognosis after surgery for small NF-PNETs in a multicenter study. Methods: Patients were identified from the databases of 16 European centers and data was extracted retrospectively. Uni- and multivariate (Cox) analyses were used to identify risk factors for recurrence. Results: 210 patients (median age 60y) were included. Median tumor size was 15mm, 65% were asymptomatic, and 42% underwent parenchyma-sparing surgery. Severe mordibidity was noted in 14% and 1 patient died postoperatively. 10% had metastatic lymph nodes. 5-year disease-free survival was excellent, 93.5%. Tumor size, presence of bile or pancreatic duct dilation, and WHO grade 2 -3 were identified as independent risk factors for recurrence. Tumors <11mm in size did not recur during follow-up. Parenchyma-sparing pancreatectomy carried highest risk for pancreatic fistula, but was also associated with favorable disease-free survival. Conclusion: Presence of bile or pancreatic duct dilation or WHO grade 2-3 advocate for surgical treatment of small (2cm or less) NF-PNETs.