Background: In gastric cancer, the classification of lymph node status is still a controversial prognostic factor. Recent studies have proposed a new prognostic factor (metastatic lymph node ratio: MLR) for gastric cancer patients who undergo curative resection. The present study tested the hypothesis that MLR was better than the current pN staging system by analyzing the correlation between MLR and the International Union Against Cancer/American Joint Committee on Cancer (UICC/AJCC) staging system, by analyzing the correlation between MLR and 5-year overall survival (OS), by comparing area under the curve (AUC), and by performing univariate and multivariate analyses for OS.
Methods: Of 409 patients who were diagnosed with gastric adenocarcinoma between January 2003 and December 2006, 370 patients underwent curative resection and were included in this study. The prognostic significance of the number of metastatic lymph nodes and the metastatic lymph node ratio were compared in AUC and univariate and multivariate Cox regression analyses.
Results: MLR was significantly correlated with the depth of invasion and the number of lymph node metastases (p < 0.001). Increasing MLR also was statistically correlated with a lower 5-year OS rate (p < 0.001). The AUC of MLR and the number of lymph node metastases were not significantly different (p = 0.825). MLR was an independent prognostic factor on multivariate analysis, but the number of metastatic lymph nodes was not.
Conclusions: MLR can be a prognostic factor in patients who undergo radical resection for gastric cancer and can overcome the limitations of existing prognostic factors.