Clinical Significance of Lymph Node Count in Colon Cancer Surgery: A Tumour Location-stratified Prognostic Analysis Based on an Integrated Phase-III Randomized Controlled Trial (JCOG2310AS3)

Abstract

Objectives: The prognostic significance of lymph node (LN) count in colon cancer (CC) remains controversial. Current guidelines recommend retrieval of ≥12 LNs for accurate staging; however, tumour sidedness may influence its prognostic relevance. This study evaluated the impact of LN count on survival according to tumour sidedness and pathological stage (pStage).

Methods: This integrated analysis used data from randomised trials conducted by the Japan Clinical Oncology Group. Data from patients with pStage II/III CC who underwent curative resection were analysed. The prognostic significance of LN count was evaluated using Cox proportional hazards models for each subgroup consisting of a combination of tumour sidedness (right-sided CC [RSCC] vs. left-sided CC [LSCC]) and pStage.

Results: A total of 2,849 patients (1,034 RSCC, 1,815 LSCC) were included. LN counts were higher in RSCC than in LSCC (median: 30 vs. 21). LN count was not independently associated with overall survival (OS) in pStage II. In contrast, in pStage III, lower LN counts were associated with worse OS on both tumour sides. In RSCC, thresholds of 9–14 (hazard ratio range: 0.17–0.50) and 26–41 (0.50–0.65) were associated with improved OS, whereas in LSCC, thresholds of 8–12 (0.34–0.61) were significant.

Conclusion: Tumour sidedness and stage were associated with the prognostic impact of LN count in patients with pStage II/III CC. LN count showed limited prognostic impact in pStage II but was associated with survival in pStage III.