Prognostic and Predictive Role of Lymph Node Count in Stage <scp>II</scp> Colon Cancer: A Retrospective Analysis of a Japanese Nationwide Cohort

ABSTRACT Aims This study aimed to reevaluate the prognostic significance of the number of harvested lymph nodes (LNs) and its predictive value for adjuvant chemotherapy (ACT) in stage II colon cancer (CC), considering tumor sidedness. Methods Pathological stage II CC patients who underwent curative surgery with Japanese D3 lymphadenectomy were assessed using a Japanese database. The optimal cutoff for harvested LNs was evaluated by analyzing all cutoff values ( n = 4–40). A Cox proportional hazards model was used to investigate the impact of the number of harvested LNs on overall survival (OS), and the impact of ACT on OS in subgroups based on the cutoff of 12 LNs and the calculated optimal cutoffs. Results A total of 3526 (left/right; 2684/842) pathological stage II CC patients were identified. A cutoff of 12LNs was identified as a prognostic factor for OS (HR 1.45; [95% CI: 1.15–1.82]). However, a stronger prognostic impact was observed with a cutoff of seven (HR 2.04; [1.44–2.88]). Subgroup analysis based on sidedness revealed variations in the optimal cutoff (7 for left‐sided [HR 2.25; (1.54–3.280)]) and 10 for right‐sided (HR 1.82; [1.02–3.26]). The survival benefit of ACT was not observed across all cutoffs. Conclusion Although cutoffs other than 12 LNs demonstrated stronger prognostic value in certain subgroups, harvesting ≥ 12 LNs remained a consistent prognostic factor across sidedness. The number of harvested LNs may not be a useful predictive factor of ACT in stage II CC.