Clinical Relevance of Lateral Pelvic Lymph Node Dissection for Enlarged Lateral Nodes in Locally Advanced Low Rectal Cancer without Preoperative Treatment

OBJECTIVES: The present study aimed to investigate the clinical relevance of lateral pelvic lymph node dissection (LPLND) in low rectal cancer without preoperative treatment, with a focus on the presence of LPLN enlargement in preoperative imaging. METHODS: Consecutive patients with cT3 to T4 low rectal cancer who underwent mesorectal excision and LPLND without preoperative treatment between 2007 and 2018 at a single dedicated cancer center were included. LPLN short-axis diameter (SAD) measured using preoperative multi-detector row computed tomography (MDCT) was evaluated retrospectively. RESULTS: A total of 195 consecutive patients were analyzed. Overall, 101 (51.8%) and 94 (48.2%) patients had visible and no visible LPLNs in preoperative imaging, including 56 (28.7%), 28 (14.4%), and 17 (8.7%) patients had SADs of <5 mm, 5-7 mm, and ≥7 mm, respectively. Incidence of pathologically confirmed LPLN metastasis were 18.1%, 21.4%, 28.6%, and 52.9%, respectively. Overall, thirteen (6.7%) patients developed local recurrence (LR), including one patient who developed lateral recurrence, yielding a 5-year cumulative risk for LR of 7.4%. Five-year RFS and OS for all patients were 69.7% and 85.7%, respectively. No differences were observed in the cumulative risk for LR and OS between any pairs of groups. CONCLUSIONS: No significant difference was observed in the cumulative risk for LR and OS regardless of LPLN SAD, implying the good impact of LPLND on the prevention of lateral recurrence, as well as the difficulty of predicting LPLN metastasis using only LPLN SAD in preoperative imaging.