Clinical Utility of ypTNM Stage Grouping in the 8th Edition of the American Joint Committee on Cancer TNM Staging System for Esophageal Squamous Cell Carcinoma

Background The 8th edition of the American Joint Committee on Cancer (AJCC) TNM staging system provided a specific ‘ypTNM’ stage grouping for patients with esophageal cancer. Objective This study aimed to evaluate the clinical utility of the AJCC 8th edition ypTNM stage grouping for patients with esophageal squamous cell carcinoma (ESCC). Methods We enrolled 152 patients with ESCC who underwent surgery after neoadjuvant cisplatin plus 5-fluorouracil (CF) therapy between June 2005 and December 2011. ypStage was evaluated according to the AJCC 7th and 8th editions. Predictive performance for disease-specific survival (DSS) and overall survival (OS) was compared between both editions. The prognostic significance of ypTNM stage grouping was evaluated using univariate and multivariate analyses. Results Revision of the AJCC 7th edition to the 8th edition was associated with a change in ypStage in 96 patients (63.2%). The AJCC 8th edition revealed a better predictive performance than the 7th edition in terms of DSS (Akaike’s information criterion [AIC] 499 vs. 513; Bayesian information criterion [BIC] 505 versus 519; concordance index [C-index] 0.725 versus 0.679) and OS (AIC 662 vs. 674; BIC 669 vs. 681; C-index 0.662 vs. 0.622). On univariate and multivariate analyses, ypStage in the 8th edition was an independent prognostic factor for both DSS and OS. Conclusions ypTNM stage grouping in the AJCC 8th edition provided a better predictive performance for DSS and OS than that in the 7th edition. ypStage in the 8th edition was the most reliable prognostic factor for ESCC patients who underwent surgery after neoadjuvant CF therapy.