Local recurrences in western low rectal cancer patients treated with or without lateral lymph node dissection after neoadjuvant (chemo)radiotherapy: An international multi-centre comparative study

Background: In the West, low rectal cancer patients with abnormal lateral lymph nodes (LLNs) are commonly treated with neoadjuvant (chemo)radiotherapy (nCRT) followed by total mesorectal excision (TME).Additionally, some perform a lateral lymph node dissection (LLND).To date, no comparative data (nCRT vs. nCRT þ LLND) are available in Western patients.Methods: An international multi-centre cohort study was conducted at six centres from the Netherlands, US and Australia.Patients with low rectal cancers from the Netherlands and Australia with abnormal LLNs (!5 mm short-axis in the obturator, internal iliac, external iliac and/or common iliac basin) who underwent nCRT and TME (LLND-group) were compared to similarly staged patients from the US who underwent a LLND in addition to nCRT and TME (LLND þ group).Results: LLND þ patients (n ¼ 44) were younger with higher ASA-classifications and ypN-stages compared to LLND-patients (n ¼ 115).LLND þ patients had larger median LLNs short-axes and received more adjuvant chemotherapy (100 vs. 30%; p < 0.0001).Between groups, the local recurrence rate (LRR) was 3% for LLND þ vs. 11% for LLND-(p ¼ 0.13).Disease-free survival (DFS, p ¼ 0.94) and overall survival (OS, p ¼ 0.42) were similar.On multivariable analysis, LLND was an independent significant factor for local recurrences (p ¼ 0.01).Sub-analysis of patients who underwent long-course nCRT and had adjuvant chemotherapy (LLND-n ¼ 30, LLND þ n ¼ 44) demonstrated a lower LRR for LLND þ patients (3% vs. 16% for LLND-; p ¼ 0.04).DFS (p ¼ 0.10) and OS (p ¼ 0.11) were similar between groups. Conclusion:A LLND in addition to nCRT may improve loco-regional control in Western patients with low rectal cancer and abnormal LLNs.Larger studies in Western patients are required to evaluate its contribution.