4108 Background: Pancreatic neuroendocrine tumors (PNET) are a heterogeneous group of tumors that represent 1-2% of all pancreatic neoplasms. Their biologic behaviors are unpredictable with high grade, nodal metastasis, or liver metastasis lending an unfavorable prognosis. Current guidelines recommend resection for functioning tumors and those 2 cm or larger but are less straightforward regarding tumors < 2 cm in size. Previous data show that observation for nonfunctioning tumors < 2 cm can be safe and feasible; however, a significant portion of these patients may have nodal involvement or metastatic disease. Methods: A retrospective review was undertaken to identify patients with pancreatic neuroendocrine tumors treated at Northern California Kaiser Permanente (KP-NCAL) between February 2010 and December 2018. Univariate and multivariate analyses were performed with the log-rank test and Cox regression. Chi-squared test of relevant clinicopathologic factors determined which factors were predictive for overall survival (OS). Results: Mean age was 61 years in our cohort of 354 patients, with 29% over the age of 70. Mean tumor size was 3.43 cm; 32% of tumors were 2 cm or smaller. 51% of the patients had localized disease; 32% of the patients presented with metastatic disease. The pancreatic tail was the most common tumor location (38%), followed by the head of the pancreas (24%). On multivariate survival analysis, stage, location of the tumor, and surgical resection were statistically significant in terms of overall survival ( p<.001). Mean OS for patients with localized and metastatic disease was 93 months versus 37 months ( p<.001). Surgery was utilized in 8.9% of patients with metastatic disease ( p<.001). All patients with PNET smaller than 1 cm in our study group had localized disease only. However, in patients with tumor size between 1 and 2 cm, 11% had nodal or metastatic spread. Conclusions: PNETs are indolent but have malignant potential at any size. In our retrospective study, all of the patients with tumor size < 1 cm had localized disease. For those with PNETs 1-2 cm in size, 11% had nodal or metastatic spread. Based on our findings, we suggest a more aggressive surgical resection size criteria of 1 cm.[Table: see text]
Overall survival benefit from surgical resection in treatment of recurrent glioblastoma
