A nomogram integrating multidimensional lymph node indicators with clinicopathological factors predicts overall survival in non-metastatic gastric cancer patients after radical gastrectomy.

Background: Non-metastatic gastric cancer patients undergoing radical gastrectomy still show substantial prognostic heterogeneity. The conventional American Joint Committee on Cancer (AJCC) tumor-node-metastasis (TNM) staging system, particularly N stage, may be affected by variations in examined lymph node (ELN), resulting in stage migration. We aimed to evaluate the efficacy of a multifactor model incorporating the log odds of positive lymph nodes (LODDS), ELN, and N stage in survival prediction for patients with non-metastatic gastric cancer undergoing radical gastrectomy, and to construct an accurate prognostic prediction model. Methods: Clinicopathological data of patients with non-metastatic gastric cancer who underwent radical gastrectomy between 2010 and 2019 were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. Independent risk factors for overall survival (OS) were determined using univariate Cox regression, least absolute shrinkage and selection operator (LASSO) regression, and multivariate Cox analysis. A nomogram was subsequently established according to these factors. The prognostic performance and clinical utility of the model were evaluated in the training, validation, and overall cohorts using the concordance index (C-index), receiver operating characteristic (ROC) curves, Akaike information criterion (AIC), calibration curves, net reclassification improvement (NRI), integrated discrimination improvement (IDI), and decision curve analysis (DCA). Patients were stratified into different risk groups based on the total nomogram scores, and the discriminatory ability was validated using Kaplan-Meier survival curves. Results: Multivariate Cox analysis revealed that age, race, tumor size, T stage, N stage, ELN, LODDS, and chemotherapy status were independent prognostic factors. The areas under the curves (AUCs) of the nomogram for predicting 1-, 3-, and 5-year OS in the training, validation, and overall cohorts all exceeded 0.76, outperforming the AJCC TNM staging system (all AUCs <0.72). Calibration curves demonstrated close agreement between predicted and observed survival outcomes. DCA, NRI, and IDI analyses further confirmed that the nomogram provided superior clinical net benefit and improved discrimination compared with the TNM staging system. The risk stratification (low-, middle-, and high-risk groups) based on the model scores significantly distinguished different survival outcomes (P<0.001). Conclusions: The nomogram integrating multidimensional factors including LODDS, ELN, and traditional TNM staging is a reliable prognostic tool for patients with non-metastatic gastric cancer after radical gastrectomy. Compared with the conventional TNM staging system, this model exhibits superior predictive accuracy and clinical applicability, assisting clinicians in individualized prognostic assessment and adjuvant treatment decision making.