Survival in differentiated thyroid carcinoma: A comparison between the 7th and 8th editions of the AJCC/UICC TNM staging system and the ATA initial risk stratification system.

Background The AJCC/UICC TNM staging system evaluates the risk of death from cancer. Its 8th edition aimed to increase its accuracy. In turn, the American Thyroid Association proposed an initial risk stratification system (IRSS) focusing on the risk of recurrence in differentiated thyroid carcinoma. The present study intended to analyze their prediction abilities. Methods Six hundred and eighty-five consecutive surgical patients (mean follow-up 71.6 months) were staged. Correlations with disease-free survival (DFS) and overall survival (OS) were carried out. Results IRSS was discriminative for DFS but not for OS. Applying TNM 8th, 36.9% of the cohort was downstaged. Their DFS was shorter, compared with other patients in the same stage, but with no impact on OS. However, all those who died of the disease had been downstaged. Conclusions IRSS was more effective to predict DFS, but not OS. TNM 8th was more appropriate for OS analysis than TNM 7th and IRSS.