Background: The need for a precise lymph node staging without stage migration is of paramount importance when comparing and evaluating international treatment results.
Methods: We reviewed 1019 patients who underwent R0 resection at Kansai Medical University between 1980 and 1997. The patients were classified according to the 1997 International Union Against Cancer (UICC)/American Joint Committee on Cancer (AJCC) pN classification or the N staging depending on the ratio between the number of excised and the number of involved lymph nodes (pN1, < or = 25%; pN2, < or = 50%; pN3, >50%).
Results: Among the 1997 UICC/AJCC pN subgroups, prognosis worsened with an increase in lymph node ratio. In contrast, the ratio-based classification showed more homogenous survival according to the number of involved lymph nodes. Multiple stepwise regression analysis showed that the ratio-based classification was the most significant prognostic factor, whereas the 1997 UICC/AJCC classification was not found to be an independent predictor of survival. In addition, the ratio-based classification showed a superiority to the 1997 UICC/AJCC classification with respect to stage migration.
Conclusions: Ratio-based lymph node staging is simple and gives more precise information for prognosis with fewer problems related to stage migration than the 1997 UICC/AJCC staging system.