A single-center experience with pancreatic cystic neuroendocrine tumors

Background Pancreatic neuroendocrine tumors (PNET) are rare, with a significant malignant potential. This study aimed to determine outcomes of patients with resected PNETs according to the cystic component and confirm the accuracy of preoperative staging. Methods From 1997 to 2016, 106 patients underwent resection of PNETs, including 73 purely solid (S-PNETs, 69%), 21 mixed (M-PNETs, 20%), and 12 purely cystic lesions (C-PNETs, 11%). To ensure consistent comparisons of overall (OS) and disease-free (DFS) survival outcomes between the 3 groups, the patients were matched according to the World Health Organization (WHO) grade and tumor height. Results Overall, the rate of correlation between the preoperative and pathological diagnoses was low in the C-PNET group (33%,P= 0.03). None of the 24 patients (23%) with metastatic disease at the time of surgery were in the C-PNET group. Furthermore, significantly more parenchyma-sparing resections (P= 0.039) and fewer enlarged resections (P= 0.019) were achieved in the C-PNET group. C-PNET group had a significantly lower node invasion rate than the S-PNET and M-PNET groups (8% vs. 41% and 24%,P= 0.004). Although median OS was comparable in all 3 groups before (P= 0.3) and after (P= 0.18) matching, higher median DFS was observed in the C-PNET group than in the other groups after matching (P= 0.038). Conclusion C-PNET was associated with a better prognosis than PNET with a solid component. The results support a wait-and-see policy in cases wherein a reliable preoperative diagnosis remains challenging.