title: Prognosis of esophageal squamous cell carcinoma patients with preoperative radiotherapy: Comparison of different cancer staging systems.
abstract: BACKGROUND
  The 7th edition American Joint Committee on Cancer tumor-node-metastasis (AJCC TNM) staging system was published in 2010. Here we evaluate its predictive ability and compare the 6th and 7th editions of the AJCC TNM staging systems in esophageal squamous cell cancer (ESCC) with preoperative radiotherapy.
  
  
  METHODS
  A total of 296 esophageal squamous cell carcinoma patients receiving preoperative radiotherapy between 1980 and 2007 were included. Patients were staged using the 6th and 7th edition staging systems. Survival analyses were performed using Cox regression models. The homogeneity, discriminatory ability, and monotonicity of gradients of the two staging systems were compared using linear trend χ(2), likelihood ratio statistics, and Akaike information criterion calculation.
  
  
  RESULTS
  The overall five-year survival rate for the entire cohort was 27.1%. Female gender, length, "T," and "N," classifications according to the 7th edition staging system were the prognostic factors in univariate analyses. However, tumor histological grade and cancer location did not significantly influence patient survival. The 7th edition staging system has the highest linear trend χ(2)and likelihood ratio χ(2)scores. Compared to the 6th edition, the 7th edition staging system also has a smaller Akaike information criterion value, which represents the optimum prognostic stratification.
  
  
  CONCLUSIONS
  The strength of the 7th edition AJCC TNM staging system lies in the new descriptors for "T" and "N" classifications. However, we did not find cancer location to be a significant prognostic factor in our cohort. Overall, the 7th edition AJCC TNM staging system performed better than the previous edition.
authors.affiliation: Department of Radiation Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences Beijing, China.
authors.forename: Qifeng
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Radiation Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences Beijing, China.
authors.forename: Wencheng
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Radiation Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences Beijing, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Pathology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences Beijing, China.
authors.forename: Xun
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Thoracic Surgery, Cancer Institute and Hospital, Chinese Academy of Medical Sciences Beijing, China.
authors.forename: Jie
authors.initials: J
authors.lastname: He
authors.affiliation: Department of Radiation Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences Beijing, China.
authors.forename: Qinfu
authors.initials: Q
authors.lastname: Feng
authors.affiliation: Department of Radiation Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences Beijing, China.
authors.forename: Zongmei
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Department of Radiation Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences Beijing, China.
authors.forename: Lvhua
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Radiation Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences Beijing, China.
authors.forename: Weibo
authors.initials: W
authors.lastname: Yin
authors.affiliation: Department of Radiation Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences Beijing, China.
authors.forename: Zefen
authors.initials: Z
authors.lastname: Xiao
keywords: AJCC cancer stage system; esophageal squamous cell carcinoma; preoperative radiotherapy; prognosis