Significance of Lateral Pelvic Lymph Node Dissection in Resectable Stage IV Low Rectal Cancer: Experience from a Single Center in Japan.

Objectives: To investigate the significance of lateral pelvic lymph node dissection (LPLND) in resectable stage IV low rectal cancers, reviewing the treatment outcomes from a single cancer center dedicated to LPLND.

Methods: Consecutive 56 patients with stage IV low rectal cancers who underwent primary tumor resection (PTR) between 2007 and 2022 were identified. Sixteen patients with non-curative PTR were excluded, and 40 with curative PTR were analyzed.

Results: The dominant metastatic organ was the liver in 30 (75.0%) patients, followed by the lung in 9 (22.5%). Seven (17.5%) patients had multiple organ metastasis. Five of 40 patients had cT1bN0 or cT2N0 disease, 8 did not receive LPLND for other reasons, and accordingly, 27 (67.5%) finally received LPLND. A total of 15 patients (37.5% of all 40 cases and 55.5% of 27 LPLND cases) had LPLN metastasis. Six (15.0%) patients had bilateral metastasis, and 6 (15.0%) had LD3 metastasis. Eight (20.0%) patients developed local recurrence (LR), and the 5Y-LR rate was 22.3%. Twelve (30.0%) patients underwent preceding chemotherapy before PTR, 26 (65.0%) received chemotherapy after PTR, and 23 (57.5%) achieved complete resection. Twelve (52.2%) of 23 patients developed distant recurrence after complete resection. 5Y-overall survival for all patients was 42.4%.

Conclusions: A high rate of LPLN metastasis implies the significance of management for LPLN metastasis; meanwhile, an unsatisfactory complete resection rate and overall survival implies that LPLN metastasis in this cohort should be dealt with as a systemic disease.