Objective:

Lymph node metastasis is known to be an important prognostic factor in the gastric cancers. In different staging classifications, the nodal involvement is evaluated in terms of the location and/or number of the metastatic lymph nodes. However, in the Western countries the minimum number of 15 lymph nodes required for an evaluation has been obtained in only 30% of the radical resections performed in the gastric cancer cases; and due to the heterogeneous survival responses in the same stage patients and the phase shifts, use of the metastatic lymph node ratio (N-ratio) rather than of the total number of positive nodes has recently been recommended for the nodal evaluation. In this study, our main objective is to retrospectively analyze the effect of the prognostic parameters to the five-year survival in the gastric cancers, and to particularly investigate the prognostic value of the N-ratio.

Methods:

The clinical records and the pathology and operation reports of the 511 patients who underwent curative surgery with a diagnosis of gastric cancer between January 2002 and December 2009 were analyzed retrospectively. The Kaplan-Meier estimator was used in the calculation of survival. The effects of the existing prognostic factors to the five-year survival were studied in univariate analyses (log-rank test) and in multivariate analyses (Cox regression model). The results were examined in a 95% confidence interval and at a p<0.05 significance level. In the N-ratio classification, the cut-off values of N0 (0%), N1 (1–10%), N2 (11–25%), and N3 (25–100%) were used.

Results:

The general rates of five-year survival were calculated as N0=74.3%, N1=66.3%, N2=59.8%, and N3=30%. When the N-ratio survival rates were compared by log-rank test, a statistically significant difference was observed among the five-year survival rates (p<0.001). The multivariate analysis (Cox regression model) involving all the prognostic factors showed that, in addition to the pT and N stages, the N-ratio was an effective independent prognostic factor in the five-year survival of the gastric cancer patients who underwent a radical resection (p<0.01). In multivariate statistical analyses in which the 6th and 7th AJCC/UICC pathological staging classifications effective to the five-year survival in the univariate analyses, and the N-ratio were involved, the N-ratio was found to be the only independent prognostic factor effecting the survival (p=0.008).

Conclusion:

The N-ratio is an easy, practical, effective and rational prognostic indicator in the gastric cancers with a lymph-node metastasis.

Keywords: Gastric cancer, lymph node metastasis, metastatic lymph node ratio, prognostic factor