The Comparison Of Different Lymph Node Staging Systems In Evaluating The Prognostic Of Gastric Cancer Patients

【Background and purpose】: Lymph node metastasis is one of most important prognostic factors to the patients with gastric cancer. N categories,based on the number of metastatic lymph nodes,could be influenced by the extension of the lymphadenectomy. This study was to evaluate the prognostic value of metastatic lymph nodes ratio(MLR) and the number of metastatic lymph nodes(pN category) in patients, with more than15lymph nodes were dissected, and to have better understanding of the two different assessment of lymph node staging in gastric cancer.【Methods】: Clinical data of250patients， who underwent radical gastrectomy and D2lymphadenectomy and more than15lymph nodes dissected，were analyzed retrospectively. We evaluated the patients by the metastatic lymph ratio with0.13and0.40as our cut-off values. We separated the patients into4groups：MLR0（MLR=0）、MLR1（0＜MLR≤13%）、MLR2（13%＜MLR≤40%）、MLR3（MLR＞40%).The correlations between the MLR and the total lymph nodes，the pN category and the total lymph nodes were analyzed respectively.The value of the MLR and pN category in prediction of the prognosis of gastric cancer were campared and evaluated.【Results】: After a median follow-up of45months (range,4to92months), the5-year overall survival of N0.N1.N2and N3was91.5%、73.4%、53.4%and29.7%（P<0.05),and the5-year overall survival of MLR0.MLR1.MLR2and MLR3was91.5%、66.1%、52.3%and13.6%(P<0.05).Spearman correlation analysis was used to determine the correlation coefficient. The metastatic lymph node ratio did not correlate with the total number of lymph nodes (r=0.08, P>0.05), whereas the number of metastatic lymph nodes did (r=0.232, P<0.05). While，the number of metastatic lymph nodes did not correlate with the total number of lymph nodes when more than27nodes were dissected (r=0.143, P>0.05).The patients, within N3stage, were divided into MLR2and MLR3subset by the MLR stage, with significantly different5-year overall survival.Multiple survival analysis was calculated by the Cox’s proportional hazard regression model. Since MLR was not retained in the Cox model, there were two independent,significant prognostic parameters: pN category （HR=1.902，P<0.05）and pT category. When MLR was included in the Cox model, the MLR （HR=2.388，P<0.05）and pT category were remained to be independent prognostic factors.There was no significant difference between the area under the receiver working characteristic curve of MLR and pN category in predicting the3-year survival rate(0.783vs0.755,P>0.05).【Conclusion】: The MLR was not correlated with the total lymph nodes dissected.It was a major independent prognostic factor.And the ability of MLR in predicting3-year survival rate is the same as that of pN category. We propose that the MLR should be considered as an alternative to the current pN category in the prediction of the prognosis of gastric cancer．...