Nodal Staging by Number of Metastatic Lymph Node and Comparison with Nodal Staging of 5th UICC TNM Classification in Gastric Cancer

ABSTRACT

PURPOSE: The nodal staging of the 5th edition of the Union Internationale Contra la Cancer (UICC) TNM classification in 1997 was changed based on the number of metastatic lymph nodes. We attempted to classify nodal status according to the number of involved lymph nodes and compare with the nodal staging of the 5th UICC TNM classification in order to evaluate the rationality of the new nodal staging system. METHODS: The authors retrospectively analyzed 427 patients with gastric cancer who underwent curative resection from 1993 to 1996 at the Department of Surgery, Korea University College of Medicine. Cumulative survival rates were calculated by the Kaplan-Meier method. The difference between each nodal status was evaluated by the log rank test and the generalized Wilcoxon test. RESULTS: There were statistical differences between 0 and 1 lymph node involved, between 7 and 8, and between 15 and 16. We classified the nodal status into 4 groups according to the number of involved lymph nodes based on the following group 1 with no lymph node involved, group 2 with 1~7, group 3 with 8~15 and group 4 with more than 15. There was a significant survival difference among the 4 groups with no survival difference between the number of positive lymph nodes in each group. We compare our results with the nodal staging of the UICC TNM classification and found that there were differences between group 2 (1~7 positive lymph nodes) and pN1 of TNM (1~6 positive lymph nodes) and between group 3 (8~15) and pN2 (7~15). CONCLUSION: We were able to classify nodal status into 4 groups according to the number of involved lymph nodes. There was little difference compared with the new nodal staging of the 5th UICC TNM classification, which suggested that the nodal classification of the UICC TNM classification based on the number of metastatic lymph nodes is acceptable. Further analysis of a larger sample size may be necessary.