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.