Introduction: After initial treatment, differentiated thyroid cancer (DTC) patients are stratified as low and high risk based on clinical/pathological features. Recently, a risk stratification based on additional clinical data accumulated during follow-up has been proposed. Objective: To evaluate the predictive value of delayed risk stratification (DRS) obtained at the time of the first diagnostic control (8-12 months after initial treatment). Methods: We reviewed 512 patients with DTC whose risk assessment was initially defined according to the American (ATA) and European Thyroid Association (ETA) guidelines. At the time of the first control, 8-12 months after initial treatment, patients were re-stratified according to their clinical status: DRS. Results: Using DRS, about 50% of ATA/ETA intermediate/high-risk patients moved to DRS low-risk category, while about 10% of ATA/ETA low-risk patients moved to DRS high-risk category. The ability of the DRS to predict the final outcome was superior to that of ATA and ETA. Positive and negative predictive values for both ATA (39.2 and 90.6% respectively) and ETA (38.4 and 91.3% respectively) were significantly lower than that observed with the DRS (72.8 and 96.3% respectively, P!0.05). The observed variance in predicting final outcome was 25.4% for ATA, 19.1% for ETA, and 62.1% for DRS. Conclusions: Delaying the risk stratification of DTC patients at a time when the response to surgery and radioiodine ablation is evident allows to better define individual risk and to better modulate the subsequent follow-up.

Background: In differentiated thyroid cancer (DTC) patients at intermediate risk of recurrences, no evidences are provided regarding the optimal radioactive iodine (RAI) activity to be administered for post-surgical thyroid ablation. Methods: This study aimed to evaluate the impact of RAI activities on the outcome of 225 DTC patients classified as intermediate risk, treated with low (1110-1850 MBq) or high RAI activities (R3700 MBq). Results: Six to 18 months after ablation, remission was observed in 60.0% of patients treated with low and in 60.0% of those treated with high RAI activities, biochemical disease was found in 18.8% of patients treated with low and in 14.3% of patients treated with high RAI activities, metastatic disease was found in 21.2% of patients treated with low and in 25.7% of patients treated with high RAI activities (PZ0.56). At the last follow-up (low activities, median 4.2 years; high activities, median 6.9 years), remission was observed in 76.5% of patients treated with low and in 72.1% of patients treated with high RAI activities, persistent disease was observed in 18.8% of patients treated with low and in 23.5% of patients treated with high RAI activities, recurrent disease was 2.4% in patients treated with low and 2.1% in patients treated with high RAI activities, deaths occurred in 2.4% of patients treated with low and in 2.1% of patients treated with high RAI activities (PZ0.87). Conclusion: Our study provides the first evidence that in DTC patients at intermediate risk, high RAI activities at ablation have no major advantage over low activities.

The results of our cytological series do not support a link between N-AIT and thyroid cancer. The association between cancer and N-AIT found in the histology-based series is likely due to a selection bias represented by the fact that the prevalent indication for surgery in the N-AIT group was suspicious cytology (60.7% of patients) more frequently than in the other groups.