Use of the Metastatic Lymph Node Ratio to Evaluate the Prognosis of Esophageal Cancer Patients with Node Metastasis Following Radical Esophagectomy

OBJECTIVES The objective of this study was to investigate the number of metastatic lymph nodes (pN) and the metastatic lymph node ratio (MLR) on the post-surgical prognosis of Chinese patients with esophageal cancer (EC) and lymph node metastasis. METHODS We enrolled 353 patients who received primary curative resection for EC from 1990 to 2003. The association of pN and MLR with 5-year overall survival (OS) was examined by receiver operating characteristic (ROC) and area under the curve (AUC) analysis. The Kaplan-Meier method was used to calculate survival rates, and survival curves were compared with the log-rank test. The Cox model was employed for univariate and multivariate analyses of factors associated with 5-year OS. RESULTS The median follow-up time was 41 months, and the 1-, 3- and 5-year OS rates were 71.2%, 30.4%, and 19.5%, respectively. Univariate analysis showed that age, pN stage, and the MLR were prognostic factors for OS. Patients with MLRs less than 0.15, MLRs of 0.15-0.30, and MLRs greater than 0.30 had 5-year OS rates of 30.1%, 17.8%, and 9.5%, respectively (p < 0.001). Patients classified as pN1, pN2, and pN3 had 5-year OS rates of 23.7%, 11.4%, and 9.9%, respectively (p < 0.001). Multivariate analysis indicated that a high MLR and advanced age were significant and independent risk factors for poor OS. Patients classified as pN2 had significantly worse OS than those classified as pN1 (p = 0.022), but those classified as pN3 had similar OS as those classified as pN1 (p = 0.166). ROC analysis indicated that MLR (AUC = 0.585, p = 0.016) had better predictive value than pN (AUC = 0.565, p = 0.068). CONCLUSIONS The integrated use of MLR and pN may be suitable for evaluation of OS in Chinese patients with EC and positive nodal metastasis after curative resection.