Risk factors for and prognostic impact of lateral pelvic lymph node metastasis in patients with rectal neuroendocrine tumors: A single-center retrospective analysis of 214 cases with radial resection

Abstract Background Lateral pelvic lymph node (LPLN) metastasis of rectal neuroendocrine tumors (NETs) is rare, and its oncologic features are unknown. We aimed to investigate the oncologic impact of LPLN metastasis in patients with rectal NETs. Methods This study included 214 patients with rectal NETs who underwent curative surgery. Clinicopathological characteristics and short- and long-term outcomes were also evaluated. Results LPLN dissection was performed in 15 patients with LPLN swelling of ≥ 7 mm on preoperative imaging. Among them, 12 patients had LPLN metastases, and six of the 12 patients had LPLN metastases without mesorectal lymph node metastases (skip metastasis). Short-term outcomes were similar between the groups with and without LPLN dissection. The median follow-up time was 54.8 months, and patients with LPLN metastasis showed significantly shorter disease-free and overall survival. Among 199 patients who did not undergo LPLN dissection, only one had LPLN recurrence. In the univariate analysis, tumor depth, tumor grade, and LPLN metastasis were associated with worse overall survival. In the multivariate analysis, only LPLN metastasis was an independent predictor of overall survival. Conclusions LPLN metastasis is a poor prognostic factor in patients with rectal NETs. LPLN enlargement can be considered an indication for dissection owing to its high rate of metastasis and associated poor prognosis.