FDG PET Performed at Thyroid Remnant Ablation Has a Higher Predictive Value for Long-Term Survival of High-Risk Patients With Well-Differentiated Thyroid Cancer Than Radioiodine Uptake. (May 2015)

• Record Type: Journal Article
• Authors: Gaertner, Florian C.; Okamoto, Shozo; Shiga, Tohru; Ito, Yoichi M.; Uchiyama, Yuko; Manabe, Osamu; Hattori, Naoya; Tamaki, Nagara
• Is Part Of: Clinical nuclear medicine. Volume 40:Number 5(2015)
• Publication Date: 2015-05
• Subjects: differentiated thyroid cancer -- radioiodine therapy -- thyroid remnant ablation -- FDG PET -- radioiodine uptake -- overall survival; Nuclear medicine -- Periodicals; Radioisotope scanning -- Periodicals; Nuclear Medicine -- Periodicals; 616.07575
• DOI: 10.1097/RLU.0000000000000699
• Languages: English
• ISSNs: 0363-9762

Abstract

Abstract : Purpose: The predictive value of FDG PET at thyroid remnant ablation was evaluated in comparison to radioiodine uptake in high-risk patients with differentiated thyroid cancer. Patients and Methods: One hundred forty-one patients who underwent radioiodine therapy (RIT) after total thyroidectomy and received at least 1 further RIT due to suspected metastases were retrospectively analyzed. Patients had not received RIT previously. FDG PET was performed before thyroid remnant ablation. Thyroid-stimulating hormone–stimulated serum thyroglobulin (Tg) was measured for biochemical response assessment (change of Tg between the first and second RIT, ΔTg). Results: Biochemical response could be evaluated in 80 patients; survival data could be obtained for 88 patients (maximum, 124 months). Biochemical response was significantly better in patients with radioiodine-positive metastases compared with patients with radioiodine-negative metastases (median ΔTg I+, 55.8% vs I−, 112.6%; P < 0.01). Regarding survival, deaths occurred later in patients with radioiodine-positive metastases compared with radioiodine-negative patients; however, there was no significant difference regarding overall survival (I+, 61.3% vs I−, 58.2%; P > 0.05). Patients with FDG-positive metastases at thyroid remnant ablation showed a poorer biochemical response compared with patients with FDG-negative metastases (median ΔTg FDG+, 77.5% vs FDG−, 53.2%; P < 0.05), and these groups also differed significantly regarding survival (overall survival FDG+, 48.5% vs FDG−, 100%, P < 0.05). Conclusions: At thyroid remnant ablation, FDG PET is more predictive for long-term survival, whereas radioiodine uptake is more important for short-term response. FDG PET performed at thyroid remnant ablation might represent a useful tool for management of high-risk patients with differentiated thyroid cancer.