Usefulness of the log odds of positive lymph nodes to predict and discriminate prognosis in gastric carcinomas.

BACKGROUND: The lymph node ratio (LNR) and log odds of positive lymph nodes (LODDS) have been proposed to minimize the stage migration phenomenon. The value of the LODDS and LNR staging systems to predict and discriminate prognosis was assessed and compared to the International Union Against Cancer (UICC) TNM classification (pN). METHODS: Three hundred and twenty-six patients with gastric carcinoma were retrospectively studied. Disease-specific survival rates were calculated for every pN, LNR, and LODDS category. RESULTS: Four LNR categories (0, 1-25, 26-75, and >76 %) and four LODDS categories (-5 to -3, > -3 to -1, > -1 to 3, and >3 to 5) were established. In the multivariate analysis, only the stage pT3-4 versus pT1-2 (HR 1.88, 95 % CI 1.11-3.20, p=0.02) and LODDS as continuous variable (HR 1.40, 95 % CI 1.21-1.61, p<0.001) remained as independent prognostic factors. In patients with <16 lymph nodes retrieved, only the LODDS system could discriminate different disease-specific survival curves for every category. LODDS categories were able to discriminate subgroups with different prognoses in pN stages and LNR categories. CONCLUSIONS: The LODDS staging system was superior to the pN classification and LNR system to discriminate risk prognosis especially in patients with an insufficient number of retrieved lymph nodes.