Effect of lateral lymph node dissection for mid and low rectal cancer: An ad-hoc analysis of the ACTS-RC (JFMC35-C1) randomized clinical trial

Background: Lateral lymph node dissection has been 1 of the standard treatments for mid and ow rectal cancer in Japan. The aim of this ad-hoc analysis was to evaluate the impact of lateral lymph node dissection on outcomes in the randomized clinical trial, referred to as the Adjuvant Chemotherapy for Stage II/III Rectal Cancer trial. Methods: The Adjuvant Chemotherapy for Stage II/III Rectal Cancer trial was a randomized, phase III trial of adjuvant chemotherapy of 2 different oral fluoropyrimidines; 445 patients with lower rectal cancer were studied in this ad-hoc analysis out of 959 patients in total, 215 of whom underwent lateral lymph node dissection and 230 did not. Results: There were no significant differences in background characteristics of the patients in the group, except for in age and number of dissected lymph nodes, between the lateral lymph node dissection and without lateral lymph node dissection groups. The age of the younger patients was often used to select candidates for lateral lymph node dissection (lateral lymph node dissection versus non–lateral lymph node dissection; 63.5 ± 8.9 vs 60.7 ± 9.4 [P =.0017]). Lateral lymph node dissection had no impact on relapse-free survival (hazard ratio = 0.941, 95% confidence interval: 0.696–1.271) or overall survival (hazard ratio = 0.858, 95% confidence interval: 0.601–1.224) in all patients with mid and low rectal cancer. In subset analysis, lateral lymph node dissection improved relapse-free survival in female patients and in patients with stage B/C or N3/4 disease. For cumulative recurrence across all patients, the proportion of patients with distant recurrence was slightly greater in the lateral lymph node dissection group but there was no difference in local recurrence. Conclusion: This exploratory analysis did not show that lateral lymph node dissection improves relapse-free survival and overall survival in patients with mid and low rectal cancer. Lateral lymph node dissection may, however, have a prognostic impact on patients with highly invasive rectal cancer.