RT Journal Article
SR Electronic
T1 [<sup>18</sup>F]-FDG Uptake as a Marker of Residual Anaplastic and Poorly Differentiated Thyroid Carcinoma following <em>BRAF</em>-Targeted Therapy
JF American Journal of Neuroradiology
JO Am. J. Neuroradiol.
FD American Society of Neuroradiology
DO 10.3174/ajnr.A8588
A1 Dagher, Samir A.
A1 Learned, Kim O.
A1 Dagher, Richard
A1 Wang, Jennifer Rui
A1 Zhao, Xiao
A1 Hosseini, S. Mohsen
A1 Maniakas, Anastasios
A1 Cabanillas, Maria E.
A1 Busaidy, Naifa L.
A1 Dadu, Ramona
A1 Iyer, Priyanka
A1 Zafereo, Mark E.
A1 Khalaf, Alexander M.
YR 2025
UL http://www.ajnr.org/content/early/2025/05/22/ajnr.A8588.abstract
AB BACKGROUND AND PURPOSE: Neoadjuvant BRAF-directed therapy and immunotherapy followed by surgery improves survival in patients with BRAFV600E-mutant anaplastic thyroid carcinoma (ATC), more so in those who have complete ATC pathologic response. This study assesses the ability of FDG-PET to noninvasively detect residual high-risk pathologies including ATC and poorly differentiated thyroid carcinoma (PDTC) in the preoperative setting.MATERIALS AND METHODS: This retrospective, single-center study included consecutive BRAFV600E-mutant patients with ATC treated with at least 30 days of neoadjuvant BRAF-directed therapy and who underwent FDG-PET/CT within 30 days before surgery. The highest pathologic grade observed for every head and neck lesion resected was recorded. Each lesion on preoperative PET/CT was retrospectively characterized. The primary end point was to contrast the standardized uptake normalized by lean body mass (SULmax) for lesions with residual high-risk (ATC, PDTC) versus low-risk pathologies (papillary thyroid carcinoma, negative). An optimal SULmax threshold was then identified by using a receiver operating characteristic analysis, and the ability of this threshold to noninvasively and preoperatively risk-stratify patients by overall survival was then evaluated with a Kaplan-Meier plot.RESULTS: Thirty patients (mean age 66.5 ± 9.0; 17 men) were included in this study, with 94 surgically sampled lesions. Of these lesions, 57 (60.6%) were low-risk (39 negative, 18 papillary thyroid carcinoma) and 37 (39.4%) were high-risk (29 ATC, 8 PDTC). FDG uptake was higher for high-risk compared with low-risk pathologies: median SULmax 5.01 (interquartile range [IQR] 2.81–10.95) versus 1.29 (IQR 1.06–3.1) (P &lt; .001, Mann-Whitney U test). The sensitivity, specificity, and accuracy for detecting high-risk pathologies at the optimal threshold of SULmax ≥2.75 were 0.784 [95% CI, 0.628–0.886], 0.702 [95% CI, 0.573–0.805], and 0.734 [95% CI, 0.637–0.813], respectively. Patients with at least 1 high-risk lesion identified with the aforementioned cutoff had a worse prognosis compared with patients without high-risk lesions in the head and neck: median overall survival for the former group was 259 days and was not attained for the latter (P = .038, log-rank test).CONCLUSIONS: Preoperative FDG-PET noninvasively identifies lesions with residual high-risk pathologies following neoadjuvant BRAF-directed targeted therapy and immunotherapy for BRAF-mutated ATC. FDG-PET avidity may serve as an early prognostic marker that correlates with residual high-risk pathology in BRAF-mutated ATC after neoadjuvant therapy.ATCanaplastic thyroid carcinomaIQRinterquartile rangeOSoverall survivalPDTCpoorly differentiated thyroid carcinomaPTCpapillary thyroid carcinomaROCreceiver operating characteristicSULstandardized uptake value normalized by lean body mass