Prognostic value of preablative stimulated thyroglobulin and its decline after ¹³¹I therapy in differentiated thyroid...

The incidence of differentiated thyroid cancer (DTC) has been increasing, highlighting the need for reliable predictors of treatment response. This study aimed to assess the prognostic value of stimulated thyroglobulin (sTg) levels before and after the first ¹³¹I treatment in DTC patients without distant metastases.

Sixty patients were classified into excellent response (ER) and non-excellent response (NER) groups based on a comprehensive evaluation of imaging findings, sTg, suppressed Tg and other parameters. Clinical and pathological variables were analyzed using univariate and multivariate logistic regression. Receiver operating characteristic (ROC) curve analysis was used to determine optimal cut-off values for pre-¹³¹I sTg levels and for the rate of sTg decline after the first ¹³¹I therapy.

Both pre-¹³¹I sTg level (OR: 3.010, 95% CI: 1.004-9.029, p = 0.049) and the rate of sTg decline (OR: 0.756, 95% CI: 0.590-0.968, p = 0.026) were identified as independent predictors of clinical outcomes. The optimal threshold for pre-¹³¹I sTg was 14.55 μg/L (sensitivity: 95.0%, specificity: 67.5%, AUC: 0.804), and for the rate of sTg decline, 44.75% (sensitivity: 70.0%, specificity: 97.5%, AUC: 0.889). A prognostic nomogram was developed incorporating sex, age, pre- and post-¹³¹I sTg levels, T and N stages, tumor size, and thyroiditis.

Lower pre-¹³¹I sTg levels and/or a greater rate of sTg decline after the first ¹³¹I treatment are associated with more favorable clinical outcomes. The proposed nomogram may assist clinicians in optimizing treatment decisions and stratifying follow-up strategies for patients with DTC.