Abstract:Background and Aims Postoperative lymph node metastasis is a major determinant of prognosis in colorectal cancer (CRC). However, reliable and convenient preoperative predictive tools remain limited. Inflammatory markers derived from routine blood tests, such as neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR), have shown potential prognostic value. This study aimed to identify risk factors and develop a predictive model for postoperative lymph node metastasis in CRC patients.Methods A total of 125 CRC patients who underwent radical surgery between January 2020 and December 2023 were retrospectively enrolled and followed for one year. Patients were divided into metastasis (n=31) and non-metastasis groups (n=94). Clinicopathologic features and preoperative blood parameters were collected. Univariate analysis and multivariate logistic regression were performed to identify independent risk factors. A nomogram model was constructed and evaluated using the concordance index (C-index), calibration curve, and receiver operating characteristic (ROC) curve.Results Univariate analysis showed that tumor size ≥3 cm, poor differentiation, submucosal invasion, vascular invasion, elevated neutrophil count, monocyte count, platelet count, PLR, NLR, and decreased lymphocyte count were significantly associated with lymph node metastasis (all P<0.05). Multivariate analysis identified poor differentiation (OR=2.044), submucosal invasion (OR=2.643), vascular invasion (OR=2.542), high PLR (OR=3.022), and high NLR (OR=2.380) as independent risk factors (all P<0.05). The nomogram achieved a C-index of 0.881 (95% CI=0.828-0.934), with good calibration. The AUC was 0.874 (95% CI=0.821-0.927), with a sensitivity of 91.66% and specificity of 68.05%.Conclusion The nomogram integrating pathological features and blood-derived inflammatory markers demonstrates good predictive performance for postoperative lymph node metastasis in CRC patients and may assist in individualized clinical decision-making.