Prognostic significance of the ratio between metastatic and dissected lymph nodes (n ratio) in patients with advanced gastric cancer

BACKGROUND AND OBJECTIVES: To determine the prognostic significance of the ratio between metastatic and dissected lymph nodes (n ratio) in gastric cancer patients. METHODS: We retrospectively reviewed 777 advanced gastric cancer patients who had undergone curative gastrectomy at our hospital. RESULTS: The n ratio was significantly greater in cases with a large tumor, undifferentiated tumor, lymphatic vessel invasion, or blood vessel invasion. Furthermore, the n ratio was significantly correlated with the depth of invasion, level of lymph node metastasis, and number of lymph node metastases. The prognosis for gastric cancer patients correlated well with the n ratio. Multivariate analysis indicated that the n ratio, but not the number of lymph node metastases, was an independent prognostic indicator. Moreover, the n ratio was an independent prognostic factor in N1, N2, and N3 patients defined by the Japanese Classification of Gastric Cancer (JCGC). CONCLUSIONS: The n ratio is useful for evaluating the status of lymph node metastasis in gastric cancer. Therefore, the addition of the n ratio to the N (nodal) category defined by the JCGC may be a useful strategy in the N-staging classification of gastric cancer.