Essentiality of Imaging Diagnostic Criteria Specific to Rectal Neuroendocrine Tumors for Detecting Metastatic Lymph Nodes

Abstract

Background/aim: The present study aimed to clarify an accurate diagnostic method for lymph node metastasis (LN+) in rectal neuroendocrine tumors (rNETs).

Patients and methods: This was a retrospective study of 14 rNETs and 45 rectal adenocarcinoma patients undergoing rectal resection. The short axis of LNs was measured using CT and pathological findings (43 paraffin-fixed LNs in rNETs and 786 LNs in adenocarcinoma).

Results: The size of LN+ in CT and pathological findings was smaller in rNETs than adenocarcinoma (p=0.082 and p<0.001, respectively). The AUC values of ROC curves for detecting LN+ using LN sizes on CT were 0.837 for rNETs and 0.885 for adenocarcinoma (Cut-off values: 5 mm for rNETs, 7 mm for adenocarcinoma). rNETs were diagnosed with high accuracy using the cut-off value of rNETs (5 mm) (sensitivity: 80.0%, and specificity: 87.5%).

Conclusion: The size of LN+ was smaller in rNETs than in adenocarcinoma, suggesting the essentiality of diagnostic criteria specific for rNETs.

Keywords: Rectal neuroendocrine tumor; lymph node metastasis; pre-operative staging.