Preoperative evaluation with computed tomography (CT) of the resectability of mesenteric lymph node metastases in small intestine neuroendocrine neoplasms (si-NENs): New criteria for clinicians and surgeons.

Abstract

212 Background: The 2016 European Neuroendocrine Tumor Society consensus guidelines update recommends resection of the primary tumor and all mesenteric lymph-nodes for all patients with si-NENs, both with curative and palliative purposes. Current resectability criteria are based on the degree of involvement of the superior mesenteric artery (SMA) by the metastatic lymph nodes. The aim of this work was to test these criteria for the evaluation of our patients; we included as additional criteria the degree of involvement of the superior mesenteric vein (SMV) and peritoneum, two features not covered by current literature. Methods: We retrospectively reviewed the pre-operative CT-scans of all patients with si-NENs operated at IEO (European Institute of Oncology) between 2008 and April 2018. A first analysis classified tumors as “resectable” or “unresectable” according to SMA involvement. A second analysis classified tumors as resectable or unresectable according to SMA involvement, SMV involvement (infiltration of the peripheral or proximal portion) and peritoneal involvement (presence or absence of fibrosis and retraction of the mesentery). We finally reviewed all surgery reports assessing radicality and completeness of the operation. Results: Abdominal CT-scan were available for analysis in 42 out of 47 operated patients. According to the first analysis, all three tumors classified as unresectable underwent incomplete resection, whereas out of the 39 tumors classified as resectable, six received an incomplete resection and 33 were completely resected. According to the second analysis, the nine tumors classified as unresectable underwent an incomplete resection, whereas 33 tumors classified as resectable were completely resected. Conclusions: Our retrospective analysis confirmed that SMA involvement may be useful to evaluate the resectability of the primary tumor and mesenteric lymph nodes. Furthermore, it suggested that the additional evaluation of the SMV and peritoneum involvement can allow to identify further cases of tumors for which complete resection is not possible.