265 Background: Small bowel neuroendocrine tumors (SB-NETs) frequently involve regional lymph nodes (LNs). The prognostic value of LN positivity on recurrence of disease is not well defined. The number of LNs needed to accurately stage patients is unknown. Methods: All patients with primary SB-NETs who underwent curative-intent resection at 8 institutions in the US Neuroendocrine Tumor Study Group between 2000 and 2016 were identified. Patients with distant metastatic disease were excluded. The association of LN positivity with recurrence of disease and the extent of lymphadenectomy required were analyzed. Results: Of 2182 patients with resected NETs, 203 had SB-NETs. Median age was 60 yrs, 56% were male, and median follow-up was 39 months. 83.5% of patients (n = 157) had LN positive disease. There was no difference in 3-year recurrence free survival (3-yr RFS) among patients with 1 or 2 positive LNs compared to patients with negative LNs (p = 0.63). Patients who had 3 or more positive LNs had a worse 3-yr RFS compared to those with 0, 1, or 2 positive LNs (n = 92 vs n = 73; 3-yr RFS 82% vs 92%; p < 0.001). Retrieval of 8 or more LNs was associated with a higher positive LN count compared to less than 8 LNs (4.6 vs. 1.6; p = 0.002). However, an increasing LN ratio was not associated with 3-yr RFS. When examining patients who had less than 8 lymph nodes retrieved, there was no difference in 3-yr RFS in those patients with 3 or more positive LNs compared to those with 0, 1, or 2 positive LNs (3-yr RFS: 100% vs 91%; p = 0.37). Retrieval of more than 8 lymph nodes, however, accurately discriminated patients with 3 or more positive LNs compared to those with 0, 1, or 2 positive LNs (3-yr RFS: 79.7% vs 93.5%; p = 0.005). Conclusions: For patients undergoing curative-intent resection of small bowel NETs, accurate lymph node staging requires a minimum of 8 lymph nodes for examination. 3 or more positive LNs is associated with decreased 3-yr RFS compared to 0, 1, or 2 positive lymph nodes. A thorough regional lymphadenectomy is critical for accurate staging and management of patients with small bowel neuroendocrine tumors.
Incidence and impact of textbook outcome among patients undergoing resection of pancreatic neuroendocrine tumors: results of the US neuroendocrine tumor study group
