Prognostic Implications of Preablation Stimulated Tg: A Retrospective Analysis of 2500 Thyroid Cancer Patients

Abstract

Context: The risk of persistent and recurrent disease in patients with differentiated thyroid cancer (DTC) is a continuum that ranges from very low to very high, even within the 3 primary risk categories. It is important to identify independent clinicopathological parameters to accurately predict clinical outcomes. Objective: To examine the association between pre-ablation stimulated thyroglobulin (ps-Tg) and persistent and recurrent disease in DTC patients and investigate whether incorporation of ps-Tg could provide a more individualized estimate of clinical outcomes. Design, Setting, and Participants: Medical records of 2524 DTC patients who underwent total thyroidectomy and radioiodine ablation between 2006 and 2018 were retrospectively reviewed. Main Outcome Measure: Ps-Tg was measured under thyroid hormone withdrawal before remnant ablation. Association of ps-Tg and clinical outcomes. Results: In multivariate analysis, age, American Thyroid Association (ATA) risk stratification, distant metastasis, ps-Tg, and cumulative administered activities were the independent predictive factors for persistent/recurrent disease. Receiver operating characteristic analysis identified ps-Tg cutoff (≤10.1 ng/mL) to predict disease-free status with a negative predictive value of 95%, and validated for all ATA categories. Integration of ps-Tg into ATA risk categories indicated that the presence of ps-Tg ≤ 10.1 ng/mL was associated with a significantly decreased chance of having persistent/recurrent disease in intermediate- and high-risk patients (9.9% to 4.1% in intermediate-risk patients, and 33.1% to 8.5% in high-risk patients). Conclusion: The ps-Tg (≤10.1 ng/mL) was a key predictor of clinical outcomes in DTC patients. Its incorporation as a variable in the ATA risk stratification system could more accurately predict clinical outcomes.