An enhanced treatment effect can be expected from a higher serum thyroglobulin level after radioactive iodine therapy

Predictive value of thyroglobulin after radioiodine therapy for excellent response to treatment in postoperative thyroid cancer

OBJECTIVE

This study aimed to assess the usefulness of thyroglobulin (Tg) after radioiodine (RAI) therapy in predicting excellent response (ER) to therapy in postoperative differentiated thyroid cancer (DTC).

METHODS

A retrospective observational study was conducted on postoperative DTC patients who underwent RAI from August 2018 to December 2022. Various factors were analyzed to predict ER to treatment. This involved Tg under stimulation (sTg) before RAI, Tg immediately (imTg) 112 h post-RAI and imTg/sTg(rTg). Based on the efficacy of RAI, patients were categorized into two groups: ER and non-ER (NER). Univariate logistic analysis was utilized to compare parameters between the two groups, followed by binary logistic regression analysis on factors associated with ER. Receiver operating characteristic (ROC) curves were employed to evaluate the sensitivity, specificity, and optimal diagnostic cutoff points for parameters affecting ER.

RESULTS

The analysis included 45 ER patients and 56 NER patients. Statistical significance was found in the binary logistic regression analysis for the number of lymph nodes in the lateral cervical region ( P  = 0.016), sTg ( P  = 0.021), and rTg ( P  ≤ 0.001) concerning ER. ROC curve analysis revealed that the rTg area under the curve was 0.845, with an optimal cutoff value of 11.78, sensitivity of 82.6%, and specificity of 74.5%.

CONCLUSION

Post-RAI therapy, significant value is demonstrated by rTg with high sensitivity and specificity. This provides a foundation for the evaluation and decisions about DTC treatment in advance.

The Role of Thyroglobulin in Preoperative and Postoperative Evaluation of Patients With Differentiated Thyroid Cancer

Thyroglobulin (Tg) is secreted by thyroid follicular cells and stored in the thyroid follicular lumen as a component of thyroid hormone. It is known that both benign and well-differentiated malignant thyroid tissue can secrete Tg. In recent years, growing lines of evidence have shown that Tg plays an important role in the diagnosis and metastasis of preoperative differentiated thyroid carcinoma (DTC). The levels of Tg, whether in the serum or in a fine-needle aspiration washout fluid, are usually viewed as an excellent indicator in the monitoring of postoperative DTC, including the guidance and evaluation of radioactive iodine ablation. Nevertheless, some factors limit the application of Tg, such as the method used to measure Tg and the presence of Tg antibodies. This review aimed to summarize the role of Tg in the preoperative and postoperative evaluation of patients with DTC, and the factors influencing Tg. This review could provide a reference for a more accurate application of Tg in patients with DTC.

Optimization of Predictive Performance for the Therapeutic Response Using Iodine Scan-Corrected Serum Thyroglobulin in Patients with Differentiated Thyroid Carcinoma

We investigated whether the performance of serum thyroglobulin (Tg) for response prediction could be improved based on the iodine uptake pattern on the post-therapeutic I-131 whole body scan (RxWBS) and the degree of thyroid tissue damage with radioactive iodine (RAI) therapy. A total of 319 patients with differentiated thyroid carcinoma who underwent total thyroidectomy and RAI therapy were included. Based on the presence/absence of focal uptake at the anterior midline of the neck above the thyroidectomy bed on RxWBS, patients were classified into positive and negative uptake groups. Serum Tg was measured immediately before (D0Tg) and 7 days after RAI therapy (D7Tg). Patients were further categorized into favorable and unfavorable Tg groups based on the prediction of excellent response (ER) using scan-corrected Tg developed through the stepwise combination of D0Tg with ratio Tg (D7Tg/D0Tg). We investigated whether the predictive performance for ER improved with the application of scan-corrected Tg compared to the single Tg cutoff. The combined approach using scan-corrected Tg showed better predictive performance for ER than the single cutoff of D0Tg alone (p < 0.001). Therefore, scan-corrected Tg can be a promising biomarker to predict the therapeutic responses after RAI therapy.