Comparison of the 6th and 7th Editions of the American Joint Committee on Cancer Tumor-Node-Metastasis Staging System in Patients With Resected Esophageal Carcinoma

Background: The 7th edition American Joint Committee on Cancer tumor-nodes-metastasis (AJCC TNM) staging system was published recently. We aim to evaluate its predictive ability and to compare the performance of the 6th and 7th editions of the AJCC TNM staging systems in esophageal cancer. Methods: A total of 392 esophageal squamous cell carcinoma patients receiving primary surgical resection between 1995 and 2006 were included. Patients were staged using the 6th and 7th edition staging systems. Survival analysis was performed with a Cox regression model. The homogeneity, discriminatory ability, and monotonicity of gradients of two staging systems were compared using linear trend χ², likelihood ratio χ² statistics, and Akaike information criterion calculation. Results: The overall five-year survival rate for the entire cohort was 27.1%. Female gender, "T," "N," and "M" classifications according to the 7th edition staging system definition were independent prognostic factors in multivariate analysis. But histology grade and cancer location had no significant influence on patient survival. The 7th edition staging system has the highest linear trend χ² and likelihood ratio χ² scores. Compared with the 6th edition, the 7th edition staging system also has a smaller Akaike information criterion value, which represented the optimum prognostic stratification. Conclusions: The strength of the 7th edition AJCC TNM staging system is the new descriptors for "N" and "M" classifications. However, we did not find histologic grade and cancer location to be significant prognostic factors in our cohort. Overall, the 7th edition AJCC TNM staging system has better performance than the previous edition.