Clinical Outcome and Prognosis of Differentiated Thyroid Carcinoma with Distant Metastasis

Objective To investigate the risk and prognostic factors of Radioactive iodide (RAI)-refractory (RAIR) in distant metastatic (DM) differentiated thyroid cancer (DTC). Methods DM-DTC patients who received iodine-131 radiation therapy were enrolled in this cohort study. After exclusion, 75 DTC radioiodine therapy resistant patients and 53 treatment effective patients were finally included. The clinical data, BRAF V600E and TERT promoter mutations were compared between these two groups to predict the risks of RAIR. Patients with RAIR-DM-DTC were followed up to further explore the risk factors for disease progression after iodine refractory. Results Univariate analysis showed that TERTp mutation, age at diagnosis, mean maximum tumor diameter, lymph node metastasis, synchronous metastasis or heterochronous metastasis, mean cumulative dose of RAI and preoperative Tg (pre-Tg) were statistically different between the RAIR and RAIE (radioiodine efficient) groups. Logistic regression analysis further found that the TERTp mutation may be risk factors for iodine refractory occurrence. During the follow-up of RAIR-DM-DTC patients, 41 patients developed disease progression and 24 patients had good disease control. Conclusions We found that TERTp mutation was correlated with the poor curative effect of RAI therapy in DM-DTC. Once iodine refractory occurs, patients aged 55 years or older are more likely to develop disease progression.