Multivariable analysis for complete resection rate of 10-20 mm non-metastatic rectal neuroendocrine tumors: a retrospective clinical study

Background: This retrospective study aimed to identify key factors affecting the rate of complete resection for non-metastatic rectal neuroendocrine tumors (NETs) using both transanal local excision (TLE) and endoscopic submucosal dissection (ESD). Methods: Records in the past 10 years were retrieved, for a total of 95 patients diagnosed with non-metastatic rectal NETs sized between 10-20 mm. Treatment outcomes were first compared between TLE and ESD to identify significantly associated factors. Monofactor analysis was then performed between complete and local resections to identify risk factors, which were then subjected to a multivariable analysis to identify independent risk factors. Results: Treatment outcomes between TLE and ESD were significantly associated with depth of invasion (P=0.039) and complete/local resection (P=0.048). By monofactor analysis between complete and local resections, depth of invasion, tumor size, tumor stage and endoscopic manifestation were identified to be risk factors (P=0.014, 0.003, 0.002 and 0.028, respectively). In subsequent multivariable analysis, depth of invasion and tumor size were independent risk factors, with odds ratio of 18.838 and 37.223, and 95% confidence interval of 1.242-285.800 and 2.839-488.078, respectively. Conclusion: Depth of invasion and tumor size were independent risk factors that significantly affect the complete resection rate of 10-20 mm non-metastatic rectal NETs.