Early Diagnosis And Efficacy Evaluation Of Iodine Refractory Thyroid Cancer

Objective:This series of studies was designed to investigate the early diagnosis and predictive value of thyroglobulin(Tg)in radioactive iodine refractory differentiated thyroid cancer(RAIR-DTC),and to explore the possibility of using apatinib for RAIR-DTC.Then use positron emission tomography(PET)for early assessment and prediction.Methods:The Tg status of patients with metastases DTC was analyzed retrospectively,and the relationship between the change level and the treatment response was explored.Patients with RAIR-DTC were prospectively enrolled and their response to apatinib was observed.Then we expand the sample to 20 patients to investigate the role of PET imaging in early assessment of efficacy and prognosis.Results:Totally 5.3%(2/38)of the patients treated with 131I therapy with a Tg reduction of>50%did not benefit from 1311 therapy,and 53.1%(17/32)for patients with elevated Tg levels(P<0.05).The ratio of stimulated Tg levels before and after 131I treatment(post-therapy/pre-therapy)was effective in predicting RAIR-DTC(cutoff of 0.554,sensitivity 0.9,specificity 0.477).In 10 patients treated with 750mg apatinib,the diameter of target lesions decreased from 38.8±15.7 mm to 22.8±8.12 mm in 2 cycles.90%(9/10)patients achieved partial response(PR).The maximum change in target lesion diameter(ACT%)correlated with PET parameters after one cycle of treatment[AMTV%(P=0.0019),ATLG%(P=0.0021),△SUVmax%(P=0.0443)].△MTV%and △TLG%(P=0.0019,0.0065)were related to patients’ progression-free survival(PFS).In addition,68Ga-NOTA-PRGD2 PET/CT was helpful in predicting the benefit and PFS(P=0.0016)of patients treated with apatinibConclusion:Tg can be used for the early assessment of RAIR-DTC.The decrease of Tg after treatment indicates that the higher risk to become RAIR-DTC.Apatinib can be used for the treatment of RAIR-DTC.PET imaging is helpful for early efficacy assessment and prognosis prediction.