Minimum Number of Retrieved Lymph Nodes for Staging in Gastric Cancer

ABSTRACT

PURPOSE: The lymph node (N) classification in the International Union Against Cancer (UICC) TNM staging system for gastric adenocarcinomas has been revised from the anatomic sites of metastatic lymph nodes to the number of metastatic lymph nodes. The purpose of this study was to investigate the proper number of retrieved lymph nodes for applying the new TNM staging system. MATENRIALS AND METHODS: We retrospectively studied 267 patients who had undergone a curative resection performed by one surgeon for gastric adenocarcinomas from March 1993 to December 1996 at Korea University Guro Hospital. We compared the old staging system to the new one and analyzed the number of retrieved and metastatic lymph nodes. We also analyzed the number of retrieved and metastatic lymph nodes according to the operative procedure and the extent of the lymphadenectomy, as well as the correlation of lymph-node metastasis to the number of retrieved lymph nodes. RESULTS: The mean number of retrieved lymph nodes was 34.27+/-14.18, of those 6.85+/-6.24 were metastatic. According to the extent of the lymphadenectomy, these numbers were 17.8+/-9.3 and 7.0+/-5.3 in D1, 33.1+/-14.6 and 3.0+/-3.0 in D1+alpha, 33.9+/-13.8 and 7.5+/-6.2 in D2, and 40.6+/-13.3 and 7.9+/-7.5 in D2+alpha. There was no correlation between the percentage of the specimen with positive lymph nodes and the number of retrieved lymph nodes, but a logistic regres sion analysis showed that the probability of lymph-node metastasis increased as the number of retrieved lymph nodes increased. CONCLUSION: The mean number of retrieved lymph nodes was about 34. Although by logistic regression analysis, the probability of lymph-node metastasis increased as the number of retrieved lymph nodes increased, we failed to determine the minimum number of nodes retrieved during a lymphadenectomy needed for accurate staging in a gastric adenocarcinoma. Further study is required to identify the optimum number of lymph nodes that need to be retrieved.