BRAF V600E Status and Stimulated Thyroglobulin at Ablation Time Increase Prognostic Value of American Thyroid Association Classification Systems for Persistent Disease in Differentiated Thyroid Carcinoma

Background. Stimulated thyroglobulin levels measured at the time of remnant ablation (A-hTg) and BRAF(V600E) mutation had shown prognostic value in predicting persistent disease in differentiated thyroid cancer (DTC). The aim of this study was to evaluate the prognostic role of A-hTg combined with the BRAF(V600E) status in association with the revised American Thyroid Association (ATA) risk stratification. Material and Methods. 620 patients treated for a DTC were included in this study with a median follow-up duration of 6.1 years. All patients underwent total thyroidectomy followed by radioiodine ablation. Patients with positive anti-thyroglobulin antibodies were excluded. The predictive value of A-hTg was calculated by receiver operating characteristic curve (ROC curve) analysis. The Cox proportional hazard regression model, including the BRAF status, A-hTg, and ATA classification system, was assessed to evaluate the existing persistent disease risk. Results. Taken together, the BRAF status and A-hTg levels improve the ATA risk classification in all categories. In particular, in the low-risk ATA classification, only the combination of BRAF(V600E)+A-hTg>8.9ng/ml was associated with persistent disease (P=0.001, HR 60.2, CI 95% 5.28-687). In the intermediate-risk ATA classification, BRAF(WT)+A-hTg>8.9ng/ml was associated with persistent disease (P=0.029, HR 2.71, CI 95% 1.106-6.670) and BRAF(V600E)+A-hTg>8.9ng/ml was also associated with persistent disease (P<0.001, HR 5.001, CI 95% 2.318-10.790). In the high-risk ATA classification, both BRAF(V600E)+A-hTg<8.9ng/ml and BRAF(V600E)+A-hTg>8.9 ng/ml were associated with persistent disease (P=0.042, HR 5.963, CI 95% 1.069-33.255 and P=0.002, HR 11.564, CI 95% 2.543-52.576, respectively). Conclusions. The BRAF status and stimulated thyroglobulin levels at ablation time improve the ATA risk stratification of differentiated thyroid cancer; therefore, even A-hTg could be included in risk classification factors.