Prognostic Significance of Metastatic Lymph Node Ratio in T3Gastric Cancer

Abstract

The fifth International Union Against Cancer tumor node metastasis (UICC TNM) classification, basedon the number of metastatic lymph nodes (LN), has proved to be areliable and objective method for predicting the prognosis of patientswith gastric cancer. However, the prognosis of patients with T3 gastriccancer is still heterogeneous. This study was carried out toinvestigate the validity of metastatic LN ratio as a prognostic factorin T3 gastric cancer. A retrospective analysis was performed on a totalof 833 patients that had either T3N1M0 (n = 504) orT3N2M0 (n = 329) gastric cancer by the fifth UICCclassification. A preliminary analysis revealed the cutoff values forT3N1M0 to be 10% and for T3N2M0 to be 25%. The mean metastatic LNratio was 9.0% for T3N1M0 cancer and 26.9% for T3N2M0 cancer. For theT3N1M0 stage, the patients who showed less than 10% of the metastaticLN ratio were grouped as N1-low with the others grouped as N1-high. Forthe T3N2M0 stage group, those who had less than 25% of the metastaticLN ratio were grouped as N2-low, the remainder as N2-high. Themetastatic LN ratio decreased in proportion to the extent oflymphadenectomy and it increased in relation to the increasing scale ofthe fourth N classification. The rates of recurrence were significantlydifferent according to the metastatic LN ratio in N1 and N2classification of the fifth UICC classification (p < 0.05). The5-year survival rates after gastrectomy decreased significantly byincreasing the metastatic LN ratio in both T3N1M0 cancers (p =0.0026) and T3N2M0 cancers (p = 0.0057). The metastatic LN ratiowas an independent risk factor for recurrence and poor prognosis. Ourdata suggest that the metastatic LN ratio is a significant prognosticfactor for T3 gastric cancer. Furthermore, the application of themetastatic LN ratio can provide information not only about the extentof LN metastasis but also about the extent of lymphadenectomy in T3gastric cancer.