Prognostic validation of the updated 8th edition Tumor-Node-Metastasis classification by the Union for International Cancer Control: Survival analyses of 307 patients with surgically treated gallbladder carcinoma

In December 2016, the Union for International Cancer Control (UICC) published the 8th edition of the Tumor-Node-Metastasis (TNM) classification of malignant tumors, including a number of vital changes in the definitions of the T2 category, the N category and the stages of gallbladder cancer (GBC). The clinical value of this newly updated classification in patients with surgically treated GBC has not been rigorously validated. The present study aimed to analyze the prognosis of patients with GBC in a high-volume surgical unit, and to validate the prognostic value of the new UICC TNM classification, particularly the main changes in the stages of GBC. Data from 307 patients who were surgically treated and histopathologically diagnosed with GBC between January 2011 and July 2016 in The West China Hospital (Chengdu, Sichuan, China) were retrospectively collected and analyzed. The new UICC criteria distributed 32, 60, 99 and 116 eligible patients in stages I, II, III and IV, respectively. The differences in overall survival time between each stage (I–IV) demonstrated statistical significance (P<0.05). As a result of the main change of this classification, the novel definitions of T2a and T2b effectively stratified the prognosis of patients with T2 GBC (P<0.001). Furthermore, patients with stage IIa tumors also obtained significantly improved overall survival time compared with patients with stage IIb tumors (P=0.04), whereas the comparison between patients with stage IIb and IIIa tumors did not present any notable difference (P=0.20). Additionally, the new N category stratified the survival of the patients effectively (P<0.001). Together with curative resection, this latest classification was indicated to be an independent predictor of survival via multivariate analysis (hazard ratio, 6.25; 95% confidence interval, 3.81–10.26; P<0.001). In conclusion, the newly updated UICC TNM classification could effectively reflect the clinical outcome of patients with surgically treated GBC. Furthermore, tumor location could predict the survival of surgically treated T2 GBC. The novel classification of the N category by the number of lymph nodes involved was also demonstrated to be valid.