A comparison of five competing lymph node staging schemes in a cohort of resectable gastric cancer patients

Background: New classifications for lymph node (LN) staging have recently been proposed to improve upon the UICC/AJCC N category staging convention. Ratio-based systems and logarithmic odds (LODDS) scores are two families of novel competing staging systems. We compared UICC/AJCC staging with 5 ratio and LODDS systems in predicting overall survival (OS) in patients with resected gastric cancer. Methods: Using a large population-based dataset, we identified 12,184 nonmetastatic resectable gastric cancer patients between 1988 and 2004. We compared each subject's UICC/AJCC N stage with five novel staging schemes. We analyzed the OS for each method. Our comparison metric was the log-rank Chi squared statistic; larger Chi squared statistics indicate improvements in N stage discrimination. Results: Median OS was 2.1 years (95 % CI 2.0-2.2 years), while median patient follow-up for surviving patients was 8.3 years (range, 1 month-22 years). Although all 5 staging systems were either comparable or superior to the UICC/AJCC convention, a LN ratio method outperformed others in N stage discrimination based on log-rank tests for OS. This trend was independent of the number of LNs examined. Conclusions: Novel LN staging methods have a higher degree of discrimination utility than the UICC/AJCC N convention. These methods may have a role in reducing the prognostic impact of LN count variability. Of the systems assessed, the LN ratio system that assigns greater risk attribution to cases with <16 LNs was the best classification method to predict OS in patients with resectable gastric cancer.