Tumor-ratio-metastasis staging system as an alternative to the 7th edition UICC TNM system in gastric cancer after D2 resection-results of a singleinstitution study of 1343 Chinese patients

Abstract

Background: In this study, we assessed the prognostic value of the lymph node ratio (LNR), established a hypothetical tumor-ratio-metastasis (TRM) staging system and compared it with the 7th edition International Union Against Cancer pathological N (pN) and tumor-node-metastasis (TNM) system. Patients and methods: A total of 1343 gastric cancer patients undergoing D2 resection were staged using the TRM staging system and the 7th edition TNM system. Optimal cut points of LNR were calculated using X-tile software and validated by bootstrapping. Homogeneity, discriminatory ability, and monotonicity of gradients of the TRM and TNM systems were comparedusing linear trend x 2, likelihood ratio x 2 statistics, and Akaike information criterion (AIC) calculations. Results: Optimal cut points classified patients into LNR0 (0%), LNR1 (1%-30%), LNR2 (31%-60%), and LNR3 (61%-100%) groups. In univariate, multivariate and stratified analyses, the LNR staging showed superiority to the 7th edition pN staging. The TRM staging system had higher linear trend and likelihood ratio x 2 scores and smaller AIC values compared with those for the TNM system, which represented the optimum prognostic stratification. Conclusions: The novel TRM staging system predicts survival of gastric cancer more accurately than the 7th edition TNM system. It may be considered as an alternative to TNM system. © The Author 2011. Published by Oxford University Press on behalf of the European Society for Medical Oncology. All rights reserved.