Enhancing prognostic accuracy in gastric cancer: The TNrrM staging system versus the AJCC TNM system.

Background: An accurate staging system is crucial for the management of gastric cancer (GC) patients. This study aimed to propose a novel staging system (TNrrM) based on the regional lymph node ratio (rLNR), defined as the ratio of the number of metastatic lymph nodes (LNs) to the number of examined LNs within each LN station.

Methods: The study included 3263 GC patients, with 2143 in the development set and 1120 in the validation set. For each patient, the rLNR for each LN station was calculated, and the total rLNR was obtained by summing the rLNR values of all LN stations. Optimal cut-off values for total rLNR were determined using X-tile to define the Nrr staging system. Based on combinations of T and Nrr staging, 5-year overall survival (OS) curves were generated, and the TNrrM staging system was defined by grouping stages with similar prognosis.

Results: The prognostic value of TNrrM was compared with the 8th edition of the AJCC TNM staging system, showing that TNrrM staging had higher AUC values for predicting 12- to 60-month OS, better calibration, and an increased net benefit as revealed by decision curve analysis (DCA). Stratified analysis demonstrated that TNrrM staging could effectively distinguish subgroups within TNM IIB to IIIC stagings.

Conclusion: Incorporating the rLNR, the TNrrM staging system significantly enhances prognostic accuracy for GC patients compared with the AJCC TNM system, with similar results found in the validation set.