Clinical outcomes by bone metastasis uptake pattern in differentiated thyroid cancer

Area of Science:

• Oncology
• Nuclear Medicine
• Radiology

Background:

• Differentiated thyroid cancer (DTC) with bone metastases (BM) presents varied radioactive iodine (RAI) and fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) uptake patterns.
• Understanding these patterns is crucial for predicting clinical outcomes.

Purpose of the Study:

• To evaluate how distinct RAI and ¹⁸F-FDG uptake patterns in DTC patients with BM influence clinical outcomes.
• To identify prognostic markers for progression-free survival (PFS) and overall survival (OS).

Main Methods:

• Retrospective analysis of 67 DTC patients with BM diagnosed between 2006 and 2021.
• All patients underwent ¹³¹I treatment and ¹⁸F-FDG PET/CT at diagnosis.
• Analysis of patient demographics, pathology, laboratory results, bone lesion uptake patterns, and PET/CT metabolic parameters.

Main Results:

• Three uptake patterns identified: RAI+/PET- (26.9%), RAI+/PET+ (59.7%), and RAI-/PET+ (13.4%).
• Univariate analysis showed age, serum thyroglobulin (Tg), and BM uptake pattern significantly impacted PFS and OS.
• RAI+/PET+ patients with RAI(+) ratio >50% had significantly better PFS and OS compared to those with RAI(+) ratio ≤50%.

Conclusions:

• The RAI(+) ratio is a critical determinant of clinical outcomes in DTC with BM.
• Prognosis for RAI+/PET+ patients is similar to RAI+/PET- patients, suggesting comparable biological behavior.
• Pretreatment total lesion glycolysis (tTLG) is an independent prognostic marker for PFS and OS.