Risk factors for lymph node metastasis and indication of local resection in duodenal neuroendocrine tumors.

Background and Aim: The risk factors for lymph node metastasis (LNM) of duodenal neuroendocrine tumors (DNETs) are not well identified, and a definitive standard of treatment for DNETs has not been established. In this study, we aimed to identify the risk factors for LNM and establish the indication of local resection for DNETs. Methods: We retrospectively reviewed 55 patients with 60 non-ampullary and nonfunctional DNETs. We evaluated the risk factors for LNM and compared the outcomes between endoscopic resection (ER) for DNETs <5 mm and laparoscopy and endoscopy cooperative surgery (LECS) for DNETs ≥5 mm. Results: LNM was present in four (8.7%) patients. Univariate analysis revealed that tumor size ≥10 mm, positive lymphovascular invasion (LVI), and 0-Is morphology were significantly associated with LNM (P = 0.008, P = 0.037, and P = 0.045, respectively). ER and LECS were performed for 18 and 11 DNETs, respectively. All lesions treated with ER or LECS were confined to the submucosal layer. The median tumor size was 3 mm in ER and 6 mm in LECS. Although there was no significant difference in the R0 (no residual tumor) resection rate, R0 resection was completely achieved in the LECS. No significant differences were observed in terms of complication rates. No recurrence was observed in any of the groups. Conclusions: Tumor size ≥10 mm, positive LVI, and 0-Is morphology were significant risk factors for LNM. We demonstrated that ER is feasible and could be safely applied for DNETs <5 mm, and LECS could be applied for DNETs 5-10 mm in size.