Prognostic significance of metastatic lymph node size in patients with gastric cancer

BACKGROUND: Patients with gastric cancer that has metastasized to the lymph nodes are a heterogeneous population with a variable prognosis. Stratification of these patients into prognostic groups is necessary for optimal adjuvant therapy. METHODS: The study comprised 715 patients who had undergone curative resection of a gastric neoplasm. Lymph nodes were sectioned, stained with haematoxylin and eosin, and the diameter of the largest metastatic lymph node (MLN) was measured. Patients with metastatic nodes were divided into groups n1 and n2 according to the size of the MLN. The cut-off level was set at 7 mm by a two-sample log rank test; patients in group n1 had a MLN size of 7 mm or less and those in group n2 had a MLN of 8 mm or more. RESULTS: Patients were stratified into significant prognostic groups by both the Union International Contra la Cancrum (UICC) node (N) stage and MLN size (n group). The UICC N-stage subcategories were further divided into prognostic groups according to MLN size (n group). On multivariate analysis the MLN size remained independently significant in terms of overall and disease-free survival rates, and the UICC N stage was not significant, independently of the n group. Node-positive patients with fewer than 15 lymph nodes removed at operation could also be stratified into prognostic groups by the n group. Stratification according to the TNM stage and by MLN size was superior to existing UICC TNM staging. CONCLUSION: This new method may help clinicians to design a more appropriate treatment strategy for patients with gastric cancer.