Efficacy of Endoscopic Resection for Rectal Neuroendocrine Tumors Smaller than 15 mm

Background Local resection, including endoscopic resection, is recommended for rectal neuroendocrine tumors (NETs) < 15 mm in patients without risk factors for metastasis, though the short- and long-term outcomes are unclear. Aims This study investigates the efficacy of endoscopic resection for rectal NETs < 15 mm. Methods The short- and long-term outcomes of patients with rectal NETs < 15 mm who underwent endoscopic resection and the outcomes of each endoscopic technique were analyzed. The tumors were stratified as < 10 mm (small-size group, SSG) and 10–14 mm (intermediate-size group, IMG). Results Overall, 139 lesions (SSG, n = 118; IMG, n = 21) were analyzed. All tumors were classified as G1 (n = 135) or G2 (n = 4) according to the 2019 World Health Organization grading criteria. The complete resection rate was not different between the groups ( P = 0.151). Endoscopic submucosal dissection (ESD) and endoscopic submucosal resection with a ligation device (ESMR-L) achieved complete resection rates > 90% in the SSG. The ESMR-L procedure time ( P < 0.001) and hospitalized period ( P < 0.001) were significantly shorter than those of ESD. ESD achieved a complete resection rate of 80.0% in the IMG. The tumor size did not affect the overall survival or rate of lymph node/distant metastases. Conclusions Endoscopic resection is a feasible and effective treatment for patients with rectal NETs < 15 mm without the risk factors of metastasis. ESMR-L and ESD are optimal techniques for resecting tumors smaller than 10 mm and 10–14 mm, respectively.