RT Journal Article SR Electronic T1 Predictive Value of 18F-FDG PET in Patients with Advanced Medullary Thyroid Carcinoma Treated with Vandetanib JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 756 OP 761 DO 10.2967/jnumed.117.199778 VO 59 IS 5 A1 Rudolf A. Werner A1 Jan-Stefan Schmid A1 Takahiro Higuchi A1 Mehrbod S. Javadi A1 Steven P. Rowe A1 Bruno Märkl A1 Christoph Aulmann A1 Martin Fassnacht A1 Matthias Kroiss A1 Christoph Reiners A1 Andreas K. Buck A1 Michael C. Kreissl A1 Constantin Lapa YR 2018 UL http://jnm.snmjournals.org/content/59/5/756.abstract AB Therapeutic options in advanced medullary thyroid carcinoma (MTC) have markedly improved since the introduction of tyrosine kinase inhibitors (TKIs). We aimed to assess the role of metabolic imaging using 18F-FDG PET/CT shortly before and 3 mo after initiation of TKI treatment. Methods: Eighteen patients with advanced and progressive MTC scheduled for vandetanib treatment underwent baseline 18F-FDG PET/CT before and 3 mo after TKI treatment initiation. During follow-up, CT scans were obtained every 3 mo and analyzed according to RECIST. The predictive value for estimating progression-free survival (PFS) and overall survival (OS) was examined by investigating the 18F-FDG SUVmean/max of the metabolically most active lesion, as well as by analyzing clinical parameters (tumor marker doubling times [calcitonin, carcinoembryonic antigen], prior therapies, rearranged-during-transfection mutational status, and disease type). Results: Within a median follow-up of 5.2 y, 9 patients experienced disease progression after a median interval of 2.1 y, whereas the remainder had ongoing disease control (5 with a partial response and 4 with stable disease). Eight of the 9 patients with progressive disease died from MTC after a median of 3.5 y after TKI initiation. A pretherapeutic SUVmean of more than 4.0 predicted a significantly shorter PFS (1.9 y vs. 5.2 y, P = 0.04). Furthermore, sustained high 18F-FDG uptake at 3 mo with a SUVmean of more than 2.8 tended to portend an unfavorable prognosis, with a PFS of 1.9 y (vs. 3.5 y, P = 0.3). Prolonged carcinoembryonic antigen doubling times were significantly correlated with longer PFS (r = 0.7) and OS (r = 0.76, P < 0.01). None of the other clinical parameters had prognostic significance. Conclusion: Pretherapeutic 18F-FDG PET/CT provides prognostic information in patients with advanced MTC scheduled for treatment with the TKI vandetanib. A low tumor metabolism with an SUVmean of less than 4.0 before treatment predicts a longer PFS.