Background: The metastatic status of the regional node is the most significant prognostic factor for early gastric cancer (EGC). However, diverse prognoses are evident even among the same N classifications of the current tumor-node-metastasis system. The aim of this study was to evaluate the prognostic significance of the ratio of metastatic to retrieved lymph nodes (N ratio) in identifying a high-risk subgroup with node-positive EGC.
Methods: From a prospective database of 1264 EGC patients between 1987 and 1997, 156 (12.4%) were found to have histologically confirmed node metastasis. A number of prognostic factors, including the N ratio, were evaluated by univariate and multivariate analysis.
Results: The recurrence rate of node-positive EGC was 16.7% (n = 26). The overall 5-year survival rate of all patients was 84.0%. It was 26.9% and 95.4% in patients with and without recurrence, respectively (P < .0001; log-rank test). The cutoff value of the N ratio was set at .07. The 5-year survival rate of patients with an N ratio <.07 was 94.0%; this was significantly higher than the rate (72.6%) for those with a ratio >.07 (P < .0001; log-rank test). Both univariate and multivariate analysis identified the N ratio as the most significant predictive factor for recurrence and overall survival. Regarding stage migration, it shows superiority in comparison to the number-based N classification.
Conclusions: The N ratio is a more effective and rational indicator for prognostic stratification of patients with lymph node-positive EGC than the current N classification of the tumor-node-metastasis system.