Endocrine Abstracts

Introduction and Objective: The initial assessment of differentiated thyroid cancer (DTC) patients is based on the American Thyroid Association (ATA) risk stratification criteria. Dynamic risk stratification (DRS) of DTC patients takes into consideration the response to initial treatment being reassessed at 1–2 years and revealed significant shifts in the risk categories of DTC patients. We aimed to evaluate the long-term outcome of papillary thyroid cancer (PTC) patients according to the ATA risk class and DRS at the first follow-up.

Methods: We retrospectively evaluated 704 patients with low (n=372) and intermediate (n=332) risk PTC. At the first follow-up patients were divided in four subgroups according to the response to the initial therapy: excellent response (ER) 320/372 (86%), biochemical incomplete response (BIR) 31/372 (8.3%), indeterminate response (IR) 11/372 (3%), and structural disease (SD) 10/372 (2.7%) in low-risk group and ER 202/332 (60.8%), BIR 51/332 (15.4%), IR 23/332 (6.9%), SD 56/332 (16.9%) in intermediate-risk group.

Results: After a median follow-up of 9 years in the excellent subgroup of PTC patients, persistent remission was observed in 98.8% of low-risk patients and in 93.1% of intermediate-risk patients, while recurrent disease was observed in 1.2% of low-risk patients and in 6.9% of intermediate-risk patients (P=0.005). The BIR patients showed an excellent response in 58% of cases in low-risk group and in 33.3% of cases in intermediate-risk group (P=0.038). The rate of persistent disease (BIR+SD) was significantly higher (P=0.038) in intermediate-risk patients than in low-risk patients (66.7% vs 42%, respectively) due to the higher rate of SD in intermediate-risk than in low-risk patients (15.7% vs 6.5%, respectively). All patients with IR had an excellent response at the last follow-up, regardless the initial ATA risk class. Finally, in patients with SD, after additional treatments, the rate of excellent response was only slightly not statistically significant between low and intermediate risk group (80% vs 46.4%, respectively) (P=0.08).

Conclusions: The long-term outcome according to the dynamic risk stratification of PTC patients is still poorly characterized. In our study we found a better clinical outcome of low-risk PTC patients for each subgroup of response to initial therapy, suggesting that the initial ATA risk class should be ta-king into account in the long-term management of PTC patients.