Analysis Factors Influencing The Efficacy Of ¹³¹I Ablation Therapy In Patients With Distant Metastasis Of Differentiated Thyroid Carcinoma And Clinical Features Of Radioactive Iodine Refractory Thyroid Carcinoma

Background and ObjectiveThyroid carcinoma is the seventh most common malignant tumor in china,ranking fourth in female malignancies.Papillary thyroid carcinoma(PTC)and follicular thyroid carcinoma(FTC)account for more than 95% of thyroid cancer,of which have a better tumor cell differentiation degree,collectively referred to differentiated thyroid carcinoma(DTC),5-year survival rate was 98%.But about 50% patients with distant metastasis will progress to radioactive iodine-refractory thyroid carcinoma(RAIR-DTC),they can not benefit from RAI therapy,of which 10-year survival rates are less than 10%.Conventional treatments for thyroid cancer include surgery and RAI treatment.RAI treatment is a specific treatment for DTC patients,which can significantly reduce the risk of recurrence and death as well as prolong disease-free survival,even though the patients had distant metastasis.First-time RAI therapy is the first step and a very important part for DTC treatment.How to determine the initial dose of RAI treatment for DTC patients with distant metastasis,and how much dose will benefit patients better,clear these factors influence the efficacy of RAI therapy may give answers to these question.RAIR-DTC patients cannot benefit from RAI treatment,and lack of effective treatment.With the improvement of science technology,we had found some of the molecular pathways responsible for thyroid cancer,bring hope for RAIR-DTC treatment,but still no effective way to diagnosis it earlier.This study aimed to analyze the factors affecting the first-time RAI treatment effect of DTC patients with distant metastasis,explore these reasons.Found out the clinical features of RAIR-DTC,aimed to help clinical diagnosis.METHODSThere were 168 DTC patients with distant metastases underwent RAI therapy in the Department of Nuclear Medicine of the Affiliated Tumor Hospital of Zhengzhou University during the period of 2016.08.01-2018.12.31,a total of 105 patients with complete medical datas were enrolled in the study,and were performed.The groups were separated through the efficacy of RAI ablation therapy respectively.Retrospective analyzed age,gender,pathological type,tumor stage,lymph node metastasis,distant metastasis position,TNM stage,24 h iodine absorption rate,interval time between last surgery and RAI treatment,TSH level,sTg level,sTgAb level,sTg/TSH ratio,dose of RAI,size as well as number of pulmonary lesions between the two groups.And then separated groups through whether patients’ progress were RAIR-DTC or not,retrospective analyzed age,gender,pathological type,tumor stage,lymph node metastasis,distant metastasis position,TNM stage,24 h iodine absorption rate,TSH level,sTg level,sTgAb level,sTg/TSH ratio,size as well as number of pulmonary lesions between the two groups.RESULTS1.The efficacy and influencing factors of RAI ablation treatment for DTC patients with distant metastasisThe first RAI ablation therapy was successful in 80 of 105 patients(76.2%).From the results of single factor analysis,it can be seen that the dose of RAI,iodine refractory related to the efficacy of RAI ablation,the difference was statistically significant(p<0.05).Gender,age,pathological type,tumor stage,lymph node metastasis,distant metastasis position,TNM stage,24 h iodine absorption rate,interval time between last surgery and RAI treatment,size and number of pulmonary lesions,TSH level,sTg level,sTgAb level and the sTg/TSH ratio was not associated with the RAI ablation treatment(p>0.05).Binary logistic regression analysis showed that the dose of RAI ablation treatment was an independent influencing factor of RAI ablation treatment,increasing dose can significantly increase success rate;iodine refractory or not was another independent influencing factor for RAI ablation treatment.50.5% patients raised TNM stage after RAI ablation treatment because the find of distant metastasis.2.Analysis of clinical characteristics for RAIR-DTC patientsFrom the results of single factor analysis,size of pulmonary lesions between RAIE-DTC group and RAIR-DTC group has significant difference(P>0.05).Gender,age,pathological type,tumor stage,lymph node metastasis,TNM stage,24 h iodine absorption rate and number of pulmonary lesions between two groups have no significant difference(P<0.05).Binary logistic regression indicated that pulmonary lesions ≥1cm were the independent risk factor of RAIR-DTC.CONCLUSION1.RAI is a necessary treatment for patients with distant metastasis of DTC,and the success rate of first-time RAI ablation therapy is 76.2%.2.The dose of RAI ablation treatment is one of the main factors affecting the RAI ablation treatment efficacy for DTC patients with distant metastasis.The increase of dose can significantly increase the success rate of RAI ablation.3.The initial successful rate of RAI ablation treatment for RAIR-DTC patients is worse than RAIE-DTC patients,and the benefit they had from RAI treatment is limited.4.Pulmonary lesions ≥ 1cm is the independent risk factor of RAIR-DTC.5.It is necessary for DTC patients underwent total thyroidectomy to complete a systemic examination and re-assessment before RAI treatment.