Lymph Node Staging in Gastric Cancer: Is Location More Important Than Number?

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Abstract
To compare the impact of staging systems on the survival of 1,038 patients with gastric cancer undergoing resection for cure in a North American center. In 1997, the American Joint Committee on Cancer (AJCC) and the Union Internationale Contre le Cancer redefined N stage in gastric cancer. The number of involved nodes rather than their location defines N, and a minimum of 15 examined lymph nodes is recommended for adequate staging. In the 1988 AJCC N-staging system, N1 and N2 node metastases were defined as within 3 cm or more than 3 cm of the primary; the 1997 AJCC N stages were defined as N1 = 1 to 6 positive nodes, N2 = 7 to 15 positive nodes, and N3 = more than 15 positive nodes. Between 1985 and 1999, 1,038 patients underwent an R0 resection. Median and 5-year survival rates were compared and the Kaplan-Meier method was used to estimate median survival. The location of positive nodes did not significantly affect median survival when analyzed by the number of positive nodes. In contrast, the number of positive lymph nodes had a profound influence on survival. The new N categories served as a better discriminator of median survival when 15 or more nodes were examined. Survival estimates for stages II, IIIA, and IIIB were significantly influenced by examining 15 or more nodes. The number of positive nodes best defines the prognostic influence of metastatic lymph nodes in gastric cancer. Survival estimates based on the number of involved nodes are better represented when at least 15 nodes are examined.