Prognostic significance of the metastatic lymph node ratio in gastric cancer patients after radical resection

Objective: Our study aims to investigate the prognostic significance of metastatic lymph nodes ratio (MLR) in gastric cancer patients undergoing radical resection. Methods: 477 patients who were diagnosed with gastric adenocarcinoma with more than 15 lymph nodes dissected by postoperative pathology, undergoing radical gastrectomy were retrospectively analyzed during January 2010 to December 2011. And the clinicopathologic parameters were analyzed to investigate the relationship between the MLR staging and pN staging in assessing the prognosis of gastric cancer patients. Result: The median follow-up time is 53 months, and the overall survival time is 45.5 months on average. The estimated overall 1-year, 3-year and 5-year survival rates were 89.94%, 64.0% and 52.1% respectively. Spearman correlation analysis showed that MLR did not correlate with the inspected number of lymph nodes (P=0.657), whereas pN did (P=0.001). Univariate analysis and Cox multivariate stepwise regression analysis showed that MLR stage, histological type, tumor sites, vascular cancer embolus, lymphatic vessel invasion, pathological stage and tumor size were independent prognostic factors (P < 0.05), while pN classification, invasion depth, differentiation degree, nerve invasion, gross type were not significantly independent prognostic parameters (P > 0.05). In subgroup analysis, the MLR stage showed more homogenous survival than pN classification in pN3 stage (P=0.002), meanwhile, the pN classification showed more homogenous survival than MLR stage in MLR1 stage (P=0.000). ROC curves analysis displayed MLR was consistent with pN on evaluating the diagnostic value of prognosis in gastric cancer patients, whether staging or not (P > 0.05). Conclusions: MLR stage can be regarded as an important supplement to pN category, and the combination of MLR and pN stage will greatly improve gastric lymph stage system.