EP2012 - Robotic lateral lymph node dissection in rectal cancer: Where do we stand?

Purpose/Background: Lateral lymph node dissection (LLND) for rectal cancer remains controversial in Western practice, especially after neoadjuvant therapy. The robotic platform may facilitate precise pelvic dissection while preserving autonomic nerves. This study aimed to evaluate the feasibility, safety and oncologic outcomes of robotic LLND performed either simultaneously with total mesorectal excision (TME) or for isolated lateral recurrence.

Methods/Interventions: A retrospective single-center study was conducted between January 2017 and August 2025, including patients with rectal adenocarcinoma and suspected lateral lymph node involvement on MRI and PET scan who underwent robotic LLND. Two cohorts were analyzed: (1) LLND performed with primary rectal resection (TME group), subdivided into post-neoadjuvant (NAT) and upfront surgery; and (2) LLND for isolated lateral recurrence after rectal cancer surgery. Perioperative and oncologic outcomes were compared.

Results/Outcomes: Thirty-seven patients were included (median age, 64.5 years). Low rectal tumors accounted for 35.1%, T3 stage for 51.3%, with EMVI positivity in 45.9% and positive CRM in 48.6%. The median LLN size was 10 mm. Among 26 primary cases, 14 received NAT and 12 underwent upfront surgery. Mean operative time was 305 minutes with TME versus 200 minutes without, and median blood loss was 25 cc. Postoperative collections occurred in 19%, with one transient nerve injury. Positive LLNs were identified in 23.1% of primary cases, equally distributed between NAT and upfront groups, and in 90.9% of isolated recurrences. Recurrence after LLND occurred in 30.8% of primary cases (2 local, 3 distant, 3 combined) and in 72.7% of isolated recurrences (2 local, 1 distant, 5 combined). Within the primary cohort, 5-year OS was similar between NAT and upfront groups (50.0% vs 66.7%, p = 0.362), as were 5-year DFS (50.5% vs 56.6%, p = 0.297) and LR-DFS (74.1% vs 67.3%, p = 0.951). In the isolated recurrence group, 5-year OS was 58.3% (15.7–85.5) and 3-year DFS 16.8% (0.9–50.8).

Conclusion/Discussion: Robotic LLND is feasible and safe in both primary and recurrent settings. In primary cases, modest nodal yield supports better imaging-based selection, while similar outcomes between NAT and upfront surgery argue for a tailored approach, including watchful waiting in good responders. The high failure rate observed after surgery for isolated lateral recurrence suggests systemic disease, questioning the oncologic benefit of reoperation in this population.