The role of endoscopic ultrasonography for diagnosis of residual rectal neuroendocrine tumor

Endoscopic ultrasonography (EUS) is useful for assessing the depth and regional lymph node involvement in rectal neuroendocrine tumors (NETs). However, evidence regarding the effectiveness of EUS in identifying residual lesions in patients with incompletely resected NET is limited. We aimed to evaluate the efficacy of EUS in identifying residual rectal NETs and the clinical outcomes of salvage endoscopic treatment.

We retrospectively reviewed the records of patients who were transferred to Chosun University Hospital and received salvage treatment for incompletely resected rectal NETs between January 2012 and October 2021.

This study included 68 incompletely resected rectal NET, of which 59 were margin-positive and 9 were margin-indeterminate. EUS detection (odds ratio (OR), 8.44; 95% confidence interval (CI), 1.18–41.35) and visual detection (OR, 7.00; 95% CI, 1.50–47.48) were associated with residual lesion in patients with incompletely resected NET. EUS detection of residual lesions showed a sensitivity of 94%, specificity of 71%, positive predictive value of 88%, negative predictive value of 83%, and accuracy of 87%. All patients underwent salvage treatment with band-ligation endoscopic mucosal resection (58.8%) and endoscopic submucosal dissection (41.2%). Residual NETs were diagnosed in 47 of 68 patients (69.1%), and no recurrence was noted during the follow-up period of 51.8 ± 22.9 months.

EUS is a more sensitive method than visual detection for evaluating residual rectal NETs. Salvage endoscopic treatment for incompletely resected NETs is safe and effective.