Influence of the number of lymph nodes examined on staging of gastric cancer

Background: Nodal staging for gastric cancer according to the 1997 Union Internacional Contra la Cancrum tumour node metastasis classification is based on the number of metastatic lymph nodes. The aim of this study was to evaluate whether the number of lymph nodes examined affected staging of gastric cancer. Methods: A retrospective study was performed in 4789 consecutive patients with gastric cancer, who had undergone curative resection (R_o) from 1986 to 1995. Patients were classified according to the number of nodes examined. The number of metastatic lymph nodes and stage-stratified survival were compared. Results: There were significant differences in the number of metastatic lymph nodes and survival in stage IIIA between patients with 15 or more lymph nodes and those with fewer than 15 nodes. In analysis restricted to patients with 15 or more nodes, stage-stratified survival did not vary significantly with lymph node yields for any stage except IIIB, in which there was a significant difference between the subgroup with fewer than 20 examined lymph nodes and patients with 35 or more nodes. Conclusion: The number of lymph nodes examined did not significantly affect node staging of gastric cancer as long as at least 15 nodes were examined. For stage IIIB, more than 15 lymph nodes may be required for optimal staging.