Oncological outcomes of lateral lymph node dissection (LLND) for locally advanced rectal cancer: is LLND alone sufficient?

Background Lateral lymph node dissection (LLND) has been considered as the standard treatment strategy for locally advanced lower rectal cancer in Japan. Controversy remains around whether all patients require LLND. This study aims to examine the long-term outcomes of patients in which LLND was performed and clarify the value of LLND. Method Consecutive 458 patients with lower rectal cancer who underwent total mesorectal excision (TME) plus LLND from 1992 to 2012 were included. The long-term outcomes and risk factors for recurrent in patients performed TME + LLND were examined. We assessed the impact of LLND on survival using an estimated therapeutic index. Results The incidence of LLNM was 15.5%. The 5-year RFS and OS rates of patients with LLNM were 40.9% and 47.7%, while patients without LLNM had a good prognosis. The 5-year local recurrence (LR) rate was 9.2%, and independent risk factors for LR were T4 and LLNM. The LR rate of patients with LLNM was high (22.8%). The LLNM rate of the groups with 0, 1, 2, 3, or 4 risk factors (male, tumor location < 4 cm from anal verge, T4, and MLNM) was 3.8%, 9.2%, 18.1%, and 50.0%. The 5-year OS of the groups was 96.2%, 86.1%, 69.7%, and 48.5%. Conclusion Although patients with locally advanced lower rectal cancer who received LLND had a good prognosis, LLND alone was insufficient to control local recurrence in patients with metastatic lateral nodes.