Optimizing the indication of initial radioiodine oncolytic treatment for metastatic differentiated thyroid cancer by diagnostic I scan.

Aim: As a classic theranostic radiopharmaceutical, radioiodine (I) has been utilized in the management of differentiated thyroid cancer (DTC) for more than 8 decades, and the refinement of its clinical practice has been raised recently. This study was conducted to evaluate the efficiency of a diagnostic (Dx) I scan in optimizing the indication of initial radioiodine oncolytic treatment (ROT) for metastatic DTC by predicting therapeutic outcomes.

Results: A total of 100 patients (Dx positive, n=29; Dx negative, n=71) were eligible for patient-based analysis. The matching rate was 83.0% between the Dx and the post-therapeutic scans (kappa = 0.648, P<0.001). The biochemical remission rate and structural shrinkage rate induced by the initial ROT in the Dx-positive group were, respectively, greater than those in the Dx-negative group (83.3% vs. 17.4%, P<0.001; 37.9% vs. 4.2%, P<0.001). Notably, the predictive values of positive Dx scans for ROT responsiveness and negative Dx scans for ROT nonresponsiveness reached up to 89.7% and 84.5%, respectively.

Conclusion: This Dx scan approach seems viable in characterizing the I-avidity of metastatic DTC and plays a pivotal role in optimizing the indication of initial ROT for metastatic DTC.