Comparison of models predicting efficacy of radioiodine therapy in patients with differentiated thyroid cancer.

[INTRODUCTION] Differentiated thyroid cancer (DTC) is the most common endocrine malignancy, with incidence rising in recent decades. Despite a favorable prognosis, management remains complex, often involving thyroidectomy followed by radioactive iodine (RAI) therapy, with varying efficacy.

[OBJECTIVES] We aimed to assess predictive models for RAI therapy efficacy in patients with DTC and to identify thyroid biomarker cutoff values.

[PATIENTS AND METHODS] This retrospective study included 744 patients with DTC who underwent thyroidectomy and RAI remnant ablation at a single center. Clinicopathological factors and thyroid biomarkers were evaluated and multivariable logistic regression models were developed, adjusting for age, sex, and disease stage. Cutoff values were established to predict RAI efficacy. Treatment‑free survival was analyzed using the Kaplan-Meier curves.

[RESULTS] Overall, the models showed no significant difference in predictive performance. Stimulated thyroglobulin (sTg) emerged as a reliable predictor of RAI efficacy, with a mean cutoff value of 7.22 ng/ml. The Kaplan-Meier analysis confirmed the prognostic value of sTg for treatment‑free survival. Chronic lymphocytic thyroiditis (CLT) status tended to improve predictive accuracy, although this was not significant.

[CONCLUSIONS] sTg alone represents a practical biomarker for predicting RAI therapy efficacy in DTC, with a defined cutoff value to guide clinical decisions. Further research may clarify the role of CLT status. There is a need to advance personalized management approaches in patients with DTC undergoing RAI therapy.