Prognostic impact of lateral sentinel lymph node biopsy using indocyanine green on oncological outcomes for clinical stage II/III lower rectal cancer without suspected lateral lymph node metastasis.

Purpose: Sentinel lymph node biopsy (SLNB) can detect occult nodal metastasis. We have previously reported the safety and feasibility of indocyanine green (ICG)-guided SLNB for clinical stage II/III lower rectal cancer (RC). However, little is known about the influence of lateral pelvic SLNB using ICG on oncological outcomes. The present study aimed to evaluate the prognostic impact of lateral pelvic SLNB on oncological outcomes compared with prophylactic lateral lymph node dissection (LLND).

Methods: Participants comprised consecutive patients with clinical stage II/III lower RC who underwent lateral pelvic SLNB or prophylactic LLND (Non-SLNB) between January 2010 and December 2020. The primary outcome measure was the 5-year cumulative incidence of local recurrence (LR). Secondary endpoints included cancer-specific survival (CSS), overall survival (OS), recurrence-free survival (RFS), local recurrence-free survival (LRFS), and distant recurrence-free survival (DRFS).

Results: Among the 150 eligible patients included, 79 patients underwent lateral pelvic SLNB. Of those 79 patients, 4 patients who were SLNB-positive underwent LLND. LLND was omitted for the 75 patients who were SLNB-negative. Median follow-up was 61.0 months (range, 1.3-143.2 months). The overall recurrence rate was 30.7% (46 patients), with LR in 12.0% (18 patients). LR comprised lateral lymph node recurrence in 2.6% and central pelvic recurrence in 9.4%. No significant differences were seen between groups in terms of the frequency of LR or in CSS, OS, RFS, LRFS, or DRFS.

Conclusion: Oncological outcomes were not different between the SLNB and Non-SLNB groups. ICG-guided SLNB appears promising as a method for determining indications for LLND.