Prognostic factors of long-term outcome in surgically resectable pancreatic neuroendocrine tumors: A 12-year experience from a single center

The present study was performed to assess the prognostic factors with respect to patient survival and clinicopathological characteristics for patients who underwent surgery for pancreatic neuroendocrine tumors (PNETs). A retrospective review of patients pathologically diagnosed with PNETs at the First Affiliated Hospital, Zhejiang University School of Medicine (Hangzhou, Zhejiang, China) between September 2002 and September 2013 was conducted. The clinicopathological findings, overall survival (OS) rate and disease-free survival (DFS) rate of the patients with PNETs were analyzed. Prognostic factors were determined by univariate and multivariate analyses. A total of 104 patients were selected. The median age at presentation was 52 years (range, 19-76 years). The most common surgical procedure was distal pancreatectomy (51.0%), followed by pancreaticoduodenectomy (27.9%) and local resection of the pancreas (16.3%). The majority of the tumors were of low or moderate grade (93.3%, grade 1 or 2) and were local or regional stage (92.3%). The 1-, 3-and 5-year OS rates were 95, 85 and 73%, respectively. Meanwhile, the 1-, 3-and 5-year DFS rates were 86, 72 and 68%, respectively. The OS and DFS rates were significantly different with regard to the grade (grades 1, 2 and 3; P< 0.001) and stage (local, regional and distant disease; P<0.001). Furthermore, patients with a low Ki-67 index experienced superior OS and DFS rates compared with patients with a high Ki-67 index (P<0.001). The presence of lymph node metastasis was predictive of inferior OS and DFS rates compared with the absence of lymph node metastasis (P<0.001). OS rate for PNETs was significantly affected by resection margin status (P<0.001). In multivariable analysis, the significant factors associated with OS rate were stage (P= 0.02), grade (P< 0.001), lymph node status (P=0.025), Ki-67 index (P=0.031) and resection margin status (P< 0.001). Meanwhile, stage (P=0.001), grade (P=0.017), lymph node status (P=0.02) and Ki-67 index (P=0.016) were prognostic factors for DFS rate. In conclusion, grade, stage, Ki-67 index and lymph node involvement are significant prognostic factors for OS and DFS rates in surgically resectable PNETs. Furthermore, surgical margin status may also be an independent predictor for the prognosis of PNETs. It is anticipated that these findings may provide useful predictors of clinical survival, particularly in the setting of resected disease.