Lateral lymph node and its association with distant recurrence in rectal cancer: A clue of systemic disease

Abstract

We analyzed oncologic outcomes according to pre-/post-LPLN enlargement. Rectal cancer patients who underwent resection post-PCRT during 2008-2012 were enrolled. Magnetic resonance imaging pre-/post-PCRT were re-evaluated. LNs with short axis (SA) ≥7 mm pre-PCRT and ≥4 mm post-PCRT were defined as enlarged nodes. Of 798 patients enrolled, recurrence occurred in 55 (6.9%) local, 17 (2.1%) lateral, and 179 (22.4%) distal regions. Patients with LPLN SA ≥7 mm pre-PCRT showed worse local recurrence-free survival (RFS), lateral RFS, and distant RFS (p < 0.001, 0.002, and 0.005, respectively). LN shrinkage post-PCRT to SA<4 mm showed better 5-year local RFS (83.5% vs. 78.3%, p = 0.045), but distant RFS was similar irrespective of LN shrinkage to <4 mm. Among patients with pre-PCRT SA ≥7 mm, node shrinkage to SA<4 mm after PCRT presented with lower incidence of local recurrence but did not benefit in distant recurrence. Lateral node sampling did not improve local recurrence control, resulting in a 5-year local RFS of 75.4% in patients undergoing lateral node sampling and 83.2% in those not undergoing lateral node sampling (p = 0.722). Four (66.7%) patients had lateral recurrence in the same area of the enlarged nodes identified pre-PCRT. For patients assessed with pre-PCRT nodes ≥7 mm, response to PCRT did not guarantee better outcomes.

Keywords: Lymph node dissection; Pelvic lymph nodes; Rectal cancer; Recurrence.