Prognostic Performance of Lymph Node Ratio and Log Odds of Positive Lymph Nodes in Colorectal Cancer: A Comparative Analysis with pN Stage

AIM: The lymph node ratio (LNR) and the log odds of positive lymph nodes (LODDS) have been proposed as alternative indicators of nodal burden that may enhance prognostic stratification beyond conventional pN stage. This study aimed to evaluate the prognostic impact of LNR and LODDS on disease-free survival (DFS) and overall survival (OS) after curative resection for colorectal cancer, and to compare their performance with pN stage and total lymph nodes examined. METHODS: This retrospective study included 154 patients who underwent curative-intent resection for stage I–III colorectal cancer between 2016 and 2022. Demographic, surgical, pathological, and follow-up data were analyzed. Patients were stratified according to pN stage, LNR, and LODDS categories. DFS and OS were evaluated using Kaplan–Meier survival analysis and Cox proportional hazards regression models. Receiver operating characteristic (ROC) analyses were also performed to assess the discriminatory ability of nodal parameters. RESULTS: The median number of lymph nodes removed was 28, and adequate lymph node dissection (≥12 lymph nodes) was achieved in 94.8% of patients. During the follow-up period, 18 recurrences and 12 deaths occurred. In the DFS analysis, patients in the LNR 1–2 group showed lower 2-year DFS rates compared to the LNR 0 group (91.0% vs 96.6%). Cox regression analysis indicated a borderline increase in relapse risk in the LNR 1–2 group (hazard ratio (HR): 2.431, 95% confidence interval (CI): 0.963–6.135, p = 0.060). Although advanced pN stage was associated with lower DFS rates, statistical significance was not achieved in the regression analysis. LODDS was not significantly associated with DFS. In the exploratory multivariate analysis, the model including LNR and age showed the best discriminatory performance, and LNR remained independently associated with the risk of recurrence even after adjusting for age (HR: 2.535, 95% CI: 1.004–6.402, p = 0.049). For OS, increasing age was significantly associated with a higher risk of death (HR: 1.076, 95% CI: 1.006–1.150, p = 0.032). In addition, patients undergoing rectal surgery had a lower risk of death compared with those undergoing right/extended colectomy (HR: 0.178, 95% CI: 0.037–0.849, p = 0.030). Neither LNR nor LODDS showed a significant association with OS. ROC analysis showed limited prognostic discrimination overall, but the LNR demonstrated relatively higher predictive performance for DFS compared to pN stage and LODDS. CONCLUSIONS: Among the lymph node parameters evaluated, LNR showed a trend toward improved prognostic discrimination for short-term DFS, whereas LODDS did not demonstrate significant prognostic value in this cohort. However, the overall discriminatory performance of all lymph node indices remained limited. Therefore, these findings should be interpreted with caution, particularly given the relatively low number of outcome events.