Background: In the 8th edition of the tumor-node-metastasis (TNM) classification, the gastric cancer staging system includes two classifications: the clinical stage (cStage) and the postoperative pathologic stage. However, the correlation between the new cStage and overall survival has not been studied. Moreover, clinical N (cN) grade analysis is not included in the new clinical staging system. This study validated the prognostic value of cStage in the 8th edition of the TNM classification and the significance of N classification for pretreatment staging in gastric cancer. Methods: A total of 4374 patients with primary gastric cancer who underwent surgery at the Shizuoka Cancer Center were included. Survival analysis was conducted based on the newly proposed cStage criteria of the TNM 8th edition. Prognostic accuracy was evaluated using Harrell’s concordance index (C-index). Results: The five-year survival rates according to cStage were as follows: cStageI, 91.2%, cStageIIA: 75.1%, cStageIIB: 57.7%, cStageIII: 43.2%, cStageIVA: 31.6%, and cStageIVB: 7.7%. Significant differences were observed among all stages (P < 0.001). The cStage C-index was 0.802. Meanwhile, the five-year survival rates based on cN were as follows: cN0: 83.7%, cN1: 57.2%, cN2: 42.4%, cN3a: 22.1%, and cN3b: 0.0%. Significant differences were also observed among all cN grades (P < 0.001). Conclusions: The cStage of the 8th edition of the TNM classification has a good capability to predict prognosis; thus, it may be a useful indicator for selecting appropriate gastric cancer treatment modalities. In addition, cN can be included in developing a more precise clinical staging of gastric cancer.
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