Survival benefit of greater number of lymph nodes dissection for advanced node-negative gastric cancer patients following radical gastrectomy

A common clinicopathological factor except for T stage that could significantly influence the clinical outcome of advanced node-negative gastric cancer patients following radical gastrectomy was unknown. This study was designed to investigate the clinicopathological characteristics of these patients, and to evaluate the outcome indicators and improve the risk stratification. A total of 195 patients harboring advanced gastric adenocarcinoma with no lymph node and distant metastases and following radical gastrectomy were retrospectively analyzed from the prospectively collected database of Zhongshan Hospital of Fudan University between 2006 and 2010. The 3-year and 5-year overall survival rates of this study population were 85.0 and 69.6%. Factors influencing the overall survival were the degree of tumor differentiation, the depth of invasion and the number of lymph nodes resected (LN, cutoff = 18). Lymph node was recognized as an independent prognostic factor for overall survival of advanced node-negative gastric cancer patients, and the prognosis of the patients with greater number of lymph nodes resected (LN ≥ 18) was significantly better than those with lymph node < 18, and only the patients with T3/T4 stage could be significantly stratified by lymph node. Based on this condition, a new staging system named tumor-node-metastasis staging system for T3/T4 node-negative gastric cancer was constructed, which could have statistically different overall survival between subgroups. Lymph node was an independent prognostic factor of patients with advanced node-negative gastric cancer, and retrieval of more than 18 lymph nodes should be warranted. In addition, these patients with lesser number of lymph nodes resected might need aggressive postoperative treatment and closer follow-up.