Toward a Preoperative Classification of Lymph Node Metastases in Patients with Small Intestinal Neuroendocrine Tumors in the Era of Intestinal-Sparing Surgery

Abstract

Introduction: In patients with small intestinal neuroendocrine tumors (siNETs), surgical resection of the primary tumor and associated mesenteric lymph nodes (LNs) is recommended, but is not well standardized and can be risky in patients with superior mesenteric vessel involvement. Objective: We aimed to evaluate the correlation between the length of resected small bowel and the number of removed LNs, and to propose a preoperative morphological classification of siNET-associated LNs. Methods: The records of patients operated on for siNETs at two expert centers between August 2005 and November 2013 were analyzed. Two specialist radiologists reviewed the preoperative imaging and classified mesenteric LNs into five stages according to their proximity to the trunk and/or branches of the superior mesenteric artery. Results: 72 patients were included. The mean number of removed LNs was 12 ± 15 and the length of removed small intestine was 53 ± 43 cm. No correlation existed between the length of small bowel resection and the number of removed LNs. Overall, 9 (12%), 13 (18%), 36 (50%), 14 (19%) and 0 patients were classified into LN stages 0, I, II, III and IV. The correlation rate between the two observers was 0.98. Patients with LN stage III (hardly resectable) had more removed LNs than those with LN stages 0, I or II (easily removable). Conclusion: Optimal lymphadenectomy is not always associated with extended small bowel resection. In the era of small bowel-sparing surgery, the preoperative classification of mesenteric LNs could help to standardize the surgical management of patients with siNETs.

Update on Surgical Management of Small Bowel Neuroendocrine Tumors

“…Whole small bowel (from Treitz ligand to the ileocecal valve) inspection and palpation with both hands is of great importance for pinpointing otherwise undetectable tumors (10,18). Preoperative CT-or MRI-angiography may be useful in determining the tumor and the lymph nodes sites in relation to the vessels, so that the optimal surgical resection is feasible, with adequate length of small bowel left behind (at least three jejunal arteries) in order to prevent short bowel syndrome (28,29). Residual metastatic lymph node disease may result in mesenteric ischemia or recurrent obstructive episodes, therefore a thorough investigation and dissection of malignant lymph nodes is important (14).…”

“…A study has classified lymph node metastases into four stages in order to facilitate the preoperative surgery plan. Only stage IV metastases were considered inoperable, due to the fact that optimal lymphadenectomy would be dangerous in terms of vascularization of the remaining bowel (28).…”

“…Optimal lymphadenectomy has not yet been standardized and is rather debatable (10). Lymphadenectomy is not associated with the length of surgical specimen (28). Furthermore, the 'pizza pie' approach should be abandoned and the inverse approach should become standard (28).…”

“…Lymphadenectomy is not associated with the length of surgical specimen (28). Furthermore, the 'pizza pie' approach should be abandoned and the inverse approach should become standard (28). Lymphadenectomy should precede enterectomy with possible ileoceccal valve preservation (10,18,28,35).…”

“…Furthermore, the 'pizza pie' approach should be abandoned and the inverse approach should become standard (28). Lymphadenectomy should precede enterectomy with possible ileoceccal valve preservation (10,18,28,35). R0 resection of both primary tumor and lymph node metastases is feasible in 80% of cases (10,18,19,36).…”