Time-dependent prognostic performance of nodal metrics after curative surgery for gastric cancer

Lymph node status is a key prognostic determinant in gastric cancer. Although pathological N (pN) staging is widely used, its accuracy depends on the number of examined lymph nodes and is vulnerable to stage migration. Ratio-based nodal metrics, including lymph node ratio (LNR) and log odds of positive lymph nodes (LODDS), have been proposed as alternatives; however, their prognostic performance has mainly been assessed using static models. The time-dependent prognostic behavior of these metrics remains unclear.

Patients undergoing curative-intent gastrectomy for gastric cancer were retrospectively analyzed. Nodal status was evaluated using pN, LNR, and LODDS. Overall survival was the primary endpoint. Time-dependent receiver operating characteristic (ROC) analyses and area under the curve (AUC) values were calculated at clinically relevant postoperative time points. Early and late prognostic performances were compared, with subgroup analyses based on examined lymph node count and tumor location.

Ratio-based nodal metrics demonstrated improved prognostic discrimination in the short-term postoperative period. At 1 and 2 years, NMLN demonstrated significantly lower discriminatory performance than both LNR and LODDS. Differences between nodal metrics attenuated with longer follow-up, and AUC values largely converged at 3 and 5 years. These findings were consistent across predefined subgroups.

The prognostic performance of nodal metrics in gastric cancer varies over time. LNR and LODDS provide improved short-term postoperative risk stratification compared with conventional pN staging, whereas long-term prognostic differences decrease. Time-dependent evaluation of nodal metrics may enhance postoperative risk assessment and support individualized follow-up and treatment strategies.