ECE2021 Audio Eposter Presentations Thyroid (157 abstracts)
1On behalf of Italian Thyroid Cancer Observatory, Italy
Background
Most Differentiated Thyroid Cancer (DTC) cases typically show indolent biological behavior and a low mortality rate. Various prognostic systems are used to assess disease recurrence risk, to tailor treatment and follow-up strategies. The initial Risk Stratification System (RSS) and dynamic Response to Therapy Re-stratification (RTR) system, recommended by the 2015 American Thyroid Association (ATA) Guidelines, are the most employed. Still, they have been validated only in retrospective cohorts of single tertiary referral centers. This study aimed to verify their real-world ability to predict disease recurrence five years after initial treatment and to clarify the specific weight of the dynamic RTR system compared to the initial RSS.
Methods
A prospective and multicentric cohort of DTC patients collected by the Italian Thyroid Cancer Observatory was analyzed. The inclusion criteria were: (i) histological diagnosis of DTC: (ii) complete information on initial treatment and 1- and 5-year follow-up visits. Patients were grouped by the RSS and RTR criteria. The correlation between risk group and structural evidence of disease was evaluated by univariate and multivariate logistic regression. The predictive performances of the two systems were also compared.
Results
Seven hundred eighty patients from 24 centers were included. The risk of recurrent disease, based on the RSS, was classified as low in 450 (57.7%), intermediate in 278 (35.6%), and high in 52 (6.7%) patients. One-year response to treatment was excellent in 576 (81.2%), indeterminate in 98 (13.8%), biochemical incomplete in 12 (1.7%) and structural incomplete in 23 (3.2%) patients. At the 5-year follow-up visit, structural evidence of disease was observed in 25 patients (3.2%): 1.1% of low, 4.7% of intermediate and 13.5% of high-risk patients; 0.3% of patients with 1-year excellent response, 6.1% with an indeterminate response, 8.3% with a biochemical incomplete response and 56.5% with a structural incomplete response (χ2 test, P-value <0.0001). Multivariate logistical models showed statistically significant predictive performance for both RSS (intermediate risk: OR 4.37; 95% CI 1.5412.38; high risk: OR 13.84; 95% CI 4.2245.41) and RTR (1-year indeterminate response: OR 18.72; 95% CI 3.7294.14; biochemical incomplete response: OR 26.09; 95% CI 2.20309.54). Moreover, the dynamic stratification showed better predictive power, especially when combined with the initial risk.
Conclusions
Both ATA initial risk estimation and dynamic risk re-stratification systems effectively predict DTC recurrence, in a real-world, heterogeneous, and multicenter cohort. The dynamic stratification showed better predictive power, and it is even better when the two systems are combined.