Clinical Outcomes of Patients with Small Rectal Neuroendocrine Tumors Treated Using Endoscopic Submucosal Resection with a Ligation Device.

Background/aims: The therapeutic strategies for small rectal neuroendocrine tumors (NETs) have not been standardized. We examined the efficacy and safety of endoscopic submucosal resection with a ligation device (ESMR-L) and the long-term outcomes after endoscopic treatment.

Methods: A total of 181 patients with rectal NETs <10 mm who were treated between May 2002 and May 2017 were retrospectively enrolled. All the lesions had been resected using ESMR-L, and the follow-up strategies were determined according to the pathological examinations. The long-term outcomes after a 53-month follow-up period were also evaluated.

Results: R0 resection was achieved in 180 cases (99.4%). Lymphovascular invasion was confirmed in 67 cases (37.0%), while a curative resection was achieved in 114 cases (63.0%). One perforation (0.6%) and 11 cases with delayed bleeding (6.1%) were observed. A multivariate logistic regression analysis revealed that a tumor size > 5 mm (OR 2.06; 95% CI 1.04-4.08, p = 0.04) was a significant independent predictor of the presence of lymphovascular invasion. Of the 67 patients with non-curative resections, 11 patients underwent additional surgery; lymph node metastasis was confirmed in 2 cases (18.2%). No local or distant metastases were observed during the follow-up period in 77 patients with a curative resection, 9 patients who received additional surgery, and 50 patients with non-curative resections.

Conclusion: ESMR-L is an easy, safe and effective treatment for rectal NETs <10 mm in diameter, and the prognosis of patients seems to be good, despite a relatively high rate of lymphovascular invasion.