Lymph node staging in gastric cancer: is location more important than Number? An analysis of 1,038 patients

Abstract

Objective: 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.

Summary background data: 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.

Methods: 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.

Results: 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.

Conclusion: 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.

Figure 1. Disease-specific survival for the entire group (n = 1,038). Median follow-up was 23 months for the entire group and 36 months for survivors.

Figure 2. Disease-specific survival for the node-positive group (n = 635). Median follow-up was 17 months for the entire group and 28.5 months for survivors.

Figure 3. Comparison of disease-specific survival by (A) 1988 staging (N defined by the site of lymph node metastases) and (B) 1997 staging system (N defined as the number of involved nodes). □, Stage 0; ▿, Stage IA; ▴, Stage IB; +, Stage II; ○, Stage IIIA; •, Stage IIIB; ∗, Stage IV.