Evaluation of Prognostic Value in Thyroid Cancer and Bone Metastasis with I-131 Therapy

Objectives: This study is aimed to evaluate the risk factors for survival and prognostic value in differentiated thyroid cancer (DTC) and bone metastasis (BM) with I-131 therapy. Methods: : 67 consecutive patients with DTC and BM were included between 2006 and 2019. All patients received total or near-total thyroidectomy, radioactive iodine (RAI) treatment, I-131 whole-body scan (WBS) and Fluorine-18-fluorodesoxyglucose positron emission tomography/computed tomography (F-18-FDG PET/CT). Variables including patient’s gender, age, pathology, laboratory examination, characteristics of BM, treatment models, and metabolic parameters of F-18-FDG PET/CT were analyzed for disease progression and survival prognosis. Results: : A total of 207 BM lesions were found in 67 patients and 28 (41.79%) patients experienced disease progression. Age stratification, thyroglobulin/thyroid-stimulating hormone (Tg/TSH) level, Tg level, PET (+) ratio and RAI (+) ratio showed significant differences between patients with progression and those without progression (p<0.05). The overall survival (OS) rate was 100% at one year, 86.56% at three years, and 43.20% at five years. Base on survival analysis, Tg/TSH level, PET (+) ratio and RAI(+) ratio were independent risk factors for PFS and OS. Of parameters of PET/CT, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were the significant prognostic factors for PFS and OS in DTC and BM patients. Conclusions: : Tg/TSH level, PET (+) ratio and RAI(+) ratio are the independent risk factors for survival in patients with DTC and BM. MTV and TLG are the significant prognosis factors for PFS and OS on PET/CT imaging.