The incidence and preoperative detection of nodal metastases in resected pancreatic neuroendocrine tumors

178 Background: Pancreatic neuroendocrine tumors (pNETs) are a heterogeneous group of rare malignancies in which surgical resection remains the only curative therapy. The optimal surgical approach (enucleation vs. pancreatectomy) is controversial. This study aims to determine the 1) incidence, 2) predictors, and 3) preoperative detection of lymph node (LN) metastases in resected pNETs to help guide surgical management. Methods: A retrospective review of prospectively collected data was performed for all patients with pancreatic neuroendocrine tumors who underwent surgical resection at the University of Virginia between 1991 and 2010. The electronic medical record, radiology reports and pathology reports were used to identify patient demographics, surgical procedure, tumor functional status, type, size, location, and LN status. Results: In all, 76 patients were identified. Most tumors were non-functioning (71%) with insulinomas (13%) and gastrinomas (5%) representing the largest groups of functioning pNETs. Nineteen tumors (25%) had LN metastases at the time of resection. LN-positive tumors were significantly larger than LN-negative tumors (4.0 ± 0.4 cm vs. 2.8 ± 0.2 cm, p=0.01). Five (11%) of 46 tumors ≤ 3 cm and one (14%) of 7 tumors ≤ 1 cm had LN metastases. There were no significant relationships between LN status and either tumor type or location (head/uncinate vs. body/tail). Of patients with LN-positive tumors, preoperative CT or MRI detected the LN metastases in only 19%. Conclusions: Twenty-five percent of pNETs are associated with LN metastasis. The only predictor of LN metastasis was tumor size, but even smaller tumors were associated with LN metastasis. The sensitivity of preoperative CT and MRI is quite poor in detecting LN metastasis. Thus, formal resection with lymphadenectomy should be considered the standard of care for pNETs. [Table: see text]