Supplementary Material for: Is Metastatic Lymph Node Ratio Superior to the Number of Metastatic Lymph Nodes to Assess Outcome and Survival of Gastric Cancer?

Background: The aim of this study was to determine the prognostic value of metastatic lymph node ratio (n ratio). Patients and Methods: We retrospectively analyzed 202 patients who had undergone curative gastrectomy. The prognostic factors including UICC/AJCC TNM classification and n ratio were evaluated by univariate and multivariate analysis. Results: The n ratio was significantly higher in patients with gastric tumors with undifferentiated histology, greater size, lymphatic vessel, blood vessel and perineural invasion (PNI), and advanced stage. Multivariate analysis indicated that n ratio and pN classification were independent prognostic factors, as were age, tumor size, Borrmann classification, PNI, and tumor differentiation. The receiver operating characteristics (ROC) analysis showed that the sensitivity and the specificity of the presence of lymph node metastasis with 16 lymph nodes resected – which was required to assess the presence of lymph node involvement – were 67.1 and 66.6%, respectively. Three-year overall survival (OS) rates and the median OS time were lower in patients with <16 lymph nodes resected compared to the patients who had >16 lymph nodes resected (p = 0.04). Conclusions: Our results showed that n ratio and pN classification were independent prognostic indicators for OS of patients with radically resected gastric cancer, but the superiority of n ratio to pN stage could not be proved.