Background and objectives: To determine the prognostic value of the ratio of metastatic lymph nodes (RML) for gastric cancer and compare it to the prognostic value of the number-based pN classification.
Methods: The survival of 513 patients who underwent curative resection between 2000 and 2005 was retrieved. The prognostic value of two factors for nodal status: RML classification (RML0, 0%; RML1, < or =30%; RML2, < or =50%; RML3, >50%) and pN classification (6th TNM system), was analyzed.
Results: Both RML and pN classifications were independent prognostic factors when considered separately in multivariate analysis (P-values < 0.05). Moreover, the proportion of explained variation (PEV) analysis showed that each classification had more prognostic value than other prognostic factors in two models respectively (P-values < 0.05). The D-measure for prognostic separation was 1.563 versus 1.383 for RML versus pN. Bootstrap results for the difference of D-measures did not show a significant difference between RML and pN in terms of prognostic power (95% CI, -0.102 to 0.175).
Conclusions: RML is an independent prognostic factor for gastric cancer. However, no significant evidence is found to support the hypothesis that RML classification carries more prognostic value than pN classification.