Comparison of the 6th and 7th Editions of the UICC-AJCC TNM Classification for Esophageal Cancer

Abstract

Background: The new 7th edition of the Union for International Cancer Control-American Joint Committee on Cancer (UICC-AJCC) tumor, node, metastasis (TNM) staging system is the ratification of data-driven recommendations from the Worldwide Esophageal Cancer Collaboration database. Generalizability remains questionable for single institutions. The present study serves as a validation of the 7th edition of the TNM system in a prospective cohort of patients with predominantly adenocarcinomas from a single institution.

Methods: Included were patients who underwent transhiatal esophagectomy with curative intent between 1991 and 2008 for invasive carcinoma of the esophagus or gastroesophageal junction. Excluded were patients who had received neoadjuvant chemo(radio)therapy, patients after a noncurative resection and patients who died in the hospital. Tumors were staged according to both the 6th and the 7th editions of the UICC-AJCC staging systems. Survival was calculated by the Kaplan-Meier method, and multivariate analysis was performed with a Cox regression model. The likelihood ratio chi-square test related to the Cox regression model and the Akaike information criterion were used for measuring goodness of fit.

Results: A study population of 358 patients was identified. All patients underwent transhiatal esophagectomy for adenocarcinoma. Overall 5-year survival rate was 38%. Univariate analysis revealed that pT stage, pN stage, and pM stage significantly predicted overall survival. Prediction was best for the 7th edition, stratifying for all substages.

Conclusions: The application of the 7th UICC-AJCC staging system results in a better prognostic stratification of overall survival compared to the 6th edition. The fact that the 7th edition performs better predominantly in patients with adenocarcinomas who underwent a transhiatal surgical approach, in addition to findings from earlier research in other cohorts, supports its generalizability for different esophageal cancer practices.

Fig. 1

Kaplan–Meier overall survival curves for 358 patients stratified by N stage according to a 7th edition and b 6th edition UICC-AJCC TNM staging systems (overall log rank P < 0.01)

Fig. 2

Kaplan–Meier curves of overall survival for 358 patients stratified according to a 6th edition and b 7th edition UICC-AJCC TNM staging systems

Fig. 3

Kaplan–Meier overall survival curves for 64 UICC-AJCC 6th stage IV patients who were reclassified according to UICC-AJCC 7th edition TNM staging (log rank P = 0.43)