Unifocal versus Multiple Ileal Neuroendocrine Tumors Location: An Embryological Origin.

INTRODUCTION: Small-intestinal neuroendocrine tumors (SI-NET) are situated preferentially within the ileum. The aim was to describe a potential difference in location between unifocal and multiple ileal-NET. PATIENTS AND METHODS: Between December 2010 and December 2019, all consecutive patients who underwent resection in our European Neuroendocrine Tumor Society Center of Excellence, of at least 1 non-duodenal SI-NET, were retrospectively included. The main objective was to prove that multiple ileal-NET were mostly located on the left side of the superior mesenteric artery (SMA) axis (defined as 40 cm from the ileocecal valve), and unifocal ones on the right side. RESULTS: Ninety-four patients were included, 6 with unifocal jejunal-NET located 35 cm (range, 10-60) from the duodenojejunal angle (DJA), 44 (47%) with unifocal ileal-NET and 44 (47%) with multiple ileal-NET. The median number of tumors in multiple ileal-NET was 7 (range, 2-95), within a median small bowel segment of 105 cm (10-240). The median length between the proximal tumor and the DJA was 428 cm (300-635) and 540 cm (350-725) for the distal one; 40 (91%) of them were located on the left side of the SMA axis. In contrast, unifocal ileal-NET were located at a median distance of 577 cm (305-820) from the DJA (p < 0.001, compared to multiple ileal-NET); 30 (68%) of them were on the right side of the SMA axis (p < 0.001). CONCLUSION: Multiple ileal-NET are mostly located on the left side of the SMA axis. Further studies are warranted to explore the embryological origin of unifocal versus multiple ileal-NET.

Management and Prognosis of Localized Duodenal Neuroendocrine Neoplasms.

INTRODUCTION: The characteristics, prognostic factors, and management of duodenal neuroendocrine neoplasms (dNEN) are ill-defined, given their rarity. Whether nonsurgical management might be appropriate for patients with nonmetastatic dNEN and a good prognosis, as is the case for pancreatic NEN (pNEN), is unknown. We aimed to describe the management and prognosis of nonmetastatic dNEN patients. METHODS: All consecutive patients with nonmetastatic dNEN managed between 1981 and 2018 in 2 expert centers were included. Recurrence-free survival (RFS) and factors associated with recurrence were estimated. RESULTS: A total of 145 patients with dNEN were included. Twenty-eight patients with sporadic, nonfunctioning, small (median 7 mm) dNEN underwent endoscopic resection, with a 5-year RFS rate of 89.4%. Local recurrence occurred in 2 patients, who underwent surgery with no new events. The 5-year RFS rate was 87.9% in patients who underwent surgery. Upon univariate analysis, age, size, Ki67 index, and lymph node involvement (LN+) were significantly associated with worse RFS for all dNEN treated (endoscopy/surgery); multivariate analysis found that age, size, and LN+ were associated with worse RFS. CONCLUSION: Selected nonmetastatic dNEN had a favorable outcome, and a less invasive therapeutic strategy appeared more suitable than oncological surgery.