Clinicopathologic Determinants of Lymph Node Count and Prognostic Significance of Metastatic Lymph Node Ratio in Colorectal Cancer.

Background/Objectives: Accurate lymph node (LN) evaluation is crucial to predicting outcomes in colorectal cancer (CRC). Higher lymph node counts (LNCs) improve prognosis, whereas increased metastatic involvement worsens survival. This study aimed to identify factors associated with higher LNCs and evaluate the prognostic value of the metastatic lymph node ratio (MLNR). Methods: A retrospective analysis was performed on 989 CRC resections. Patients were stratified into four MLNR categories-MLNR0 (no metastasis), MLNR1 (<0.20), MLNR2 (0.20-0.50), and MLNR3 (>0.50)-and into two LNC groups-lower LNC (<12) and higher LNC (≥12). Results: The median LN count was 14 (range: 5-198). Lower LNCs occurred in 346 cases (35.0%), predominantly in the left colon. Higher LNCs were significantly associated with younger age (p < 0.001), larger tumor size (p < 0.001), higher pN stage (p < 0.001), right-sided location (p = 0.003), Crohn's-like lymphocytic response (p = 0.006), and the absence of satellite nodules (p = 0.016). There were 86 pT4 and 178 pN2 tumors. Overall survival was 50.6%, with the 1-, 3-, and 5-year rates being 0.891, 0.721, and 0.612, respectively. Survival was higher in patients with higher LNCs (53.5% vs. 45.1%, p < 0.001). Survival rates by MLNR were 61.2% (MLNR0), 47.7% (MLNR1), 34.0% (MLNR2), and 26.4% (MLNR3). Mortality strongly correlated with MLNR (p < 0.001), and life expectancy decreased as MLNR increased (p < 0.01). Conclusions: MLNR provides superior prognostic information compared to pN status, even in patients with suboptimal lymph node retrieval (LNC < 12). As an independent survival predictor, MLNR may be integrated into staging systems and guide therapeutic strategies, highlighting its clinical utility in both standard and "gray zone" CRC cases.