Clinical significance of positive resection margin for patients with rectal neuroendocrine tumors within 20 mm following initial endoscopic resection: A multi-center study

Background: The incidence of rectal neuroendocrine tumors (RNETs) has witnessed a significant surge, with a notable proportion being amenable to endoscopic removal. However, the clinical significance of positive resection margin for RNETs patients following endoscopic resection remain unknown, resulting in a lack of consensus regarding the appropriateness of implementing salvage treatment. Methods: In this large, multicenter, retrospective cohort study, we analyzed the medical records of individuals who underwent endoscopic resection for RNETs and classified them into two groups: the positive resection margin and the negative resection margin group. The overall survival (OS) and disease-free survival (DFS) were compared among two group. The independent variables were identified using univariate and multivariate logistic regression analyses to predict positive resection margin. Then, the model was established to predict the patients with positive resection margin using multivariate logistic regression. Results: 181 RNETs patients (34.3 %) represented positive margin after endoscopic resection. Following a median follow-up period of 72 months, tumor recurrence manifested in 12 out of 527 patients (2.2 %) and the presence of positive resection margin was associated with worse DFS. Independent factors correlating with positive resection margin included endoscopic resection method choice, RNETs located in the low rectum, NLR >4.44 and tumor size exceeding 14.89 mm. A prediction model was therefore established with high predictive accuracy and excellent clinical applicability determined by calibration curves and DCA curve. Among RNETs patients with positive margin following endoscopic resection, implementing salvage treatment was beneficial for improving DFS and salvage endoscopic resection offer equal efficiency compared with salvage radical resection. Conclusions: Positive resection margin following endoscopic resection may indicate negative prognosis. Salvage treatment can improve the prognosis of RNETs patients with positive resection margin. Notably, salvage local resection exhibited similar efficacy compared with radical surgery in term of survival benefit.