Long-term outcome of grade 1 rectal neuroendocrine tumor ≤1 cm after incomplete endoscopic resection.

Background/aims: Surveillance strategies for small grade 1 rectal neuroendocrine tumors (G1 rNETs) after incomplete endoscopic resection (ER) remain controversial. We evaluated the long-term outcomes of patients with G1 rNET ≤1 cm after ER who did and did not undergo complete resection.

Methods: We retrospectively evaluated 441 patients with G1 rNETs measuring ≤1 cm after ER between 2011 and 2022. Patients were divided into complete and incomplete resection groups according to histopathological evaluation. Logistic regression analysis identified the risk factors for incomplete resection after ER.

Results: The mean follow-up intervals were 38.6 and 45.7 months in all patients and the incomplete resection group, respectively. No recurrences were observed during the follow-up period. The mean lesion size was 5.5 mm and the complete resection rate was 80.5% (n=355). In the logistic regression analysis, lesion size 5.1 to 10 mm (odds ratio [OR], 2.3; 95% confidence interval [CI], 1.245-4.203; p=0.008), multiple lesions (OR, 8.3; 95% CI, 1.247-54.774; p=0.029), and retroflexion view during the procedure (OR, 4.0; 95% CI, 1.668-9.615; p=0.002) were independent risk factors for incomplete resection.

Conclusions: The prognosis of G1 rNET ≤1 cm after ER was very good, regardless of the histopathological results.