Introduction: There is no clear indication for radioiodine treatment (RAI) in patients affected by differentiated thyroid cancer (DTC) in Stage I and ATA intermediate risk, according to American Thyroid Association (ATA) guidelines.
Purpose: Our aim is to evaluate whether integration of BRAF status and thyroglobulin TSH-stimulated at the time of RAI (A-HTg) could further improve accuracy of stratification, and therefore therapeutic management, in DTC patients with Stage I AJCC and ATA intermediate risk.
Materials and Methods: This retrospective study involved 372 patients affected by DTC with Stage I AJCC 8th ed. and ATA intermediate risk, followed at the Endocrinology and Diabetes Prevention and Treatment Department from 2000 to 2020. For each patient we analyzed persistence of the disease one year after the initial treatment and at the end of the follow up (median: 8 years), BRAF status and A-HTg levels, respectively. By ROC curve we calculated the A-HTg cutoff of 5.9 ng/ml (sensitivity 64%, specificity 75%, AUC 0.725).
Results: In our population, 265/372 (68.8%) patients had BRAFV600E mutation, 121/372 (32.5%) A-HTg levels > 5.9 ng/ml, 91/372 (24.5%) persistent disease after one year and 75/372 (20.2%) at the end of the follow up. The presence of A-HTg levels > 5.9 ng/ml, regardless of BRAF status, was associated with a higher risk of disease persistence after one year (BRAFwt: RR 7.615, p-value < 0.001; BRAFV600E: RR 5.535, p-value < 0.001) and at the end of the follow up (BRAFwt: RR 3.004, p-value 0.038; BRAFV600E: RR 4.776, p-value < 0.001). Our population was further divided in 4 groups: A-HTg < 5.9 ng/ml and BRAFwt, A-HTg < 5.9 ng/ml and BRAFV600E, A-HTg > 5.9 ng/ml and BRAFwt, A-HTg > 5.9 ng/ml and BRAFV600E. In these subpopulations we observed a progressive increase of persistent disease after one year, respectively of 8.3%, 15.6%, 40.9% and 50.6% (P-value < 0.001), and at the end of the follow up, respectively of 9.7%, 15.1%, 24.4% and 46.2% (P-value < 0.001).
Conclusions: Among patients with Stage I and ATA intermediate risk DTC, those with high A-HTg and BRAFV600E had the maximum rate of persistent disease. Therefore, radioiodine treatment could be proposed only to this subpopulation, rather to the entire cohort of Stage I and ATA intermediate risk. Prospective studies with longer follow-up and wider population are necessary to confirm our results.
21 May 2022 - 24 May 2022