Reappraisal of the new UICC staging system for gastric cancer: problem in lymph node stage

The International Union Against Cancer (UICC) TNM staging system defined a new system for classifying gastric cancer, based on the number of metastatic nodes (1997). However, the advantage of the new system is still a matter of debate. The aim of the present study is to compare the new system with the old one (1987), which is based on the location of positive lymph nodes.

We analyzed the survival of 608 patients with curative resection of their gastric cancer. The average number of resected and involved lymph nodes for each resected patient was 31.4 and 7.7. Comparison of these two systems was carried out to determine which classification was more effective. The prognostic value of different lymph node staging systems was also analyzed.

One hundred and thirty-five patients (22.2%) had different N classification and 109 (17.9%) had different TNM staging. There was a significant stepwise decrease of slope of survival curve for each stage, but the new system did not cleanly separate stage II with IIIa at 3 years and stage IIIb with IV at 5 years. Although different lymph node staging systems were able to predict survival, the ratio rather than the number of involved nodes had a more cleanly separated stepwise decrease of slope of survival curve.

The new UICC staging system is not better than the old system for the staging of gastric cancer. The reason is that the category of node number seems not to be appropriate and will be influenced by the extent of lymph node dissection. To overcome this problem, the frequency of involved nodes can be adopted instead of the number.