Ratio between negative and positive lymph nodes is a novel prognostic indicator for patients with esophageal cancer: A Surveillance, Epidemiology and End Results database analysis

BACKGROUND: The aim of this study was to explore whether the ratio between negative and positive lymph nodes (R(NP)) could predict the overall survival (OS) of esophageal cancer (EC) patients with lymph node metastasis following esophagectomy. METHODS: We utilized the Surveillance, Epidemiology and End Results (SEER) database to include the records of 2374 patients with lymph node metastases post‐surgery. All patients were randomly assigned into the training cohort (n = 1424) and validation cohort (n = 950). Multivariate Cox regression analyses were performed to identify independent prognostic factors. A novel R(NP) ‐based TR(NP)M staging system was proposed. The prognostic value of N, R(NP), TNM and TR(NP)M staging system was evaluated using the linear trend χ(2) test, likelihood ratio χ(2) test, and Akaike information criterion (AIC) to determine the potential superiorities. We constructed nomograms to predict survival in both cohorts, and the calibration curves confirmed the predictive ability. RESULTS: Univariate analyses showed that N and R(NP) stage significantly influenced the OS of patients. Multivariate analyses revealed that R(NP) was an independent prognostic predictor in both the training and validation cohorts. For the stratification analysis in the two cohorts, we found significant differences in the prognosis of patients in different R(NP) groups on the basis of the different N stages and the number of dissected lymph nodes. In addition, the lower AIC value of R(NP) stage and TR(NP)M staging system represented superior predictive accuracy for OS than the N stage and TNM staging system, respectively. Furthermore, the calibration curves for the probability of three‐ and five‐year survival showed good consistency between nomogram predictive abilities and actual observation. CONCLUSIONS: We demonstrated that compared to the classical pathological lymph nodal staging system, the R(NP) stage showed superior predictive accuracy for OS and can serve as a more effective prognostic guidance for lymph node positive EC patients.