Prognostic Significance of the Metastatic Lymph Node Ratio in Gastric Cancer Patients

Background Lymph node metastasis is considered one of the most important prognostic factors in gastric cancer. However, the optimal system for accurate staging of lymph node metastasis for patients with gastric cancer remains controversial. This study was designed to investigate the prognostic significance of the metastatic lymph node ratio (MLR), which is calculated by dividing the number of metastatic lymph nodes by the total number of nodes harvested from patients with gastric cancer. Methods We retrospectively analyzed the clinical data of 186 consecutive patients diagnosed with gastric cancer who underwent curative gastrectomy at our hospital. The lymph node status was classified according to three systems: the International Union Against Cancer/American Joint Committee on Cancer (UICC/AJCC) system; the Japanese Gastric Cancer Association (JGCA) system; and an MLR-based system (MLR0: 0, MLR1: 0.01-0.19, MLR2: >= 0.2). The influence of the MLR on patient survival was determined using univariate Kaplan-Meier survival analysis, the generalized Wilcoxon test, and analysis with the multivariate Cox proportional hazards model. Results The 5-year survival rate of the patients with MLR0, MLR1, and MLR2 was 88.6%, 59.4%, and 13.4%, respectively. In addition to the MLR, the UICC/AJCC N category, JGCA n category, tumor stage (pT category), and tumor diameter significantly influenced the 5-year survival rate, as determined by univariate analysis. Multivariate analyses revealed that of the three factors used to stage lymph node involvement, MLR was the most significant prognostic factor. Conclusions The MLR is an important and easy-to-assess prognostic factor that should be considered for staging lymph node metastasis in patients with gastric cancer.