The Interpretation Of The Current Edition Of International Union Against Cancer Staging System For Gastric Cancer

Objective:The aim of the present study was to investigate the impact of tumor size and Log odds of positive lymph nodes (LODDS) staging system on survival of patients with gastric cancer. Finally, to explore the accuracy of the7th edition of the International Union Against Cancer tumor-nodes-metastasis (UICC/TNM) staging system for prognostic assessment of gastric cancer patients.Methods:The clinicopathologic data of484patients who underwent curative resection for gastric cancer at the Tianjin Medical University Cancer Institute and Hospital were retrospectively analyzed. Firstly, we analysised the association of tumor size with clinicopathological factors and the prognostic value of tumor size in patients with gastric cancer, and compared the survival difference of different tumor size in the same stage. Secondly, We classified the LODDS according to the most appropriate cutoff value and researched the prognostic value of the LODDS classification. In addidtion, the relation of LODDS classification or the7th edition of the International Union Against Cancer pN staging system and the number of retrieved lymph nodes were investigated. Finally, the superiority of LODDS classification and pN staging system for the prognostic evaluation was compared.Results:1、The appropriate cutoff value of tumor size was5cm. According to the cutoff value of tumor size, patients were categorized into two groups:small-size group(<5cm) and large-size group(≥5cm). Tumor size was correlated with depth of invasion, status of lymph nodes, tumor site and resection type (P<0.001). The prognosis of small-size group patients was significantly better than that of large-size group patients (P<0.001). Multivariate analysis showed that tumor size was the independent prognostic factor for gastric cancer patients (P<0.001). Tumor size significantly affected the survival in patients with stage Ⅱ and Ⅲ disease. However, there was not survival difference in the Ⅰ staging between the small-size tumor group and the large-size tumor group. 2> Multivariate analysis showed that LODDS classification was the independent prognostic factor for gastric cancer patients (P<0.001). The scatter plots and Pearson of the relationship between the number of metastatic lymph nodes and the number of retrieved lymph nodes suggested that the number of metastatic lymph nodes is closely related to the number of retrieved lymph nodes. However, The scatter plots of the relationship between the LODDS and the number of retrieved lymph nodes suggested that the value of Log odds of positive lymph nodes is not related to the number of retrieved lymph nodes. There were significant differences in survival among patients in different LODDS classifications for each pN stage. When stratified by the LODDS classifications, the prognosis was highly homologous between those in the according pN classifications.Conclusion:Tumor size is the reliable prognostic factor in patients with gastric cancer, and it can provide a special reference to the7th edition of UICC TNM staging system. The LODDS classification is not effected by the number of retrieved lymph nodes. Therefore, the LODDS classification is more reliable than the International Union Against Cancer pN stage for prognostic assessment. The LODDS classifications can effectively minimize the phenomenon of stage migration caused by insufficient nodes retrieved.