Clinical Study Of ¹³¹I Treatment For Pulmonary Metastases From Differentiated Thyroid Carcinoma

Part 1 Curative Efficacy and Influencing Factors on ¹³¹I Treatment for Pulmonary Metastases from Differentiated Thyroid CarcinomaObjective: To investigate the curative efficacy and influential factors of ¹³¹I treatment for pulmonary metastases from differentiated thyroid carcinoma.Methods: 95 patients（33 males,62 females）with pulmonary metastases who underwent ¹³¹I treatment in Department of Nuclear Medicine,Xinhua Hospital,Shanghai Jiao Tong University School of Medicine,from April 2012 to May 2016 were retrospectively analyzed.The efficacy of ¹³¹I treatment was assessed using determination of serum thyroglobulin（Tg）level and RECIST（version 1.1）.The possible factors affecting efficacy were analyzed by Univariate analysis and Logistic regression.Results: The rate of efficacy and invalid of ¹³¹I treatment were 53.68% and 46.32% respectively.Univariate analyses showed that ¹⁸F-FDG uptake（P=0.004）,the size of lung metastasis（P=0.000）,age <45y（P=0.004）,¹³¹I uptake（P=0.022）,whether pulmonary metastasis diagnosed before treatment（P=0.000）,extrapulmonary distant metastasis（P=0.014）were the factors influencing outcome of ¹³¹I treatment.The critical value of ¹⁸F-FDG uptake for patients obtained by ROC curve was 1.45（sensitivity 56.8%,specificity 76.5%）and the critical value of lung lesion diameter was 9.63mm（sensitivity 43.2%,specificity 88.2%）.Multivariate Logistic regression analysis showed that the influential factors included the age of patients,the size and ¹⁸F-FDG uptake of lung metastases and whether pulmonary metastasis diagnosed before treatment.Conclusion: ¹³¹I treatment is an effective method for pulmonary metastases from DTC.The patients <45 years,with the lesion size less-than 9.63 cm,lower ¹⁸F-FDG uptake and diagnosed at the beginning have good response to ¹³¹I treatment.Part 2 Prognostic Value of ¹⁸F-FDG Uptake in 131 l Avidity Pulmonary Metastases from Differentiated Thyroid CancerPurpose: The lungs are the most frequent distant site for metastases in patients with differentiated thyroid cancer（DTC）.Iodine uptake is a necessary condition for ¹³¹I treatment.Positive ¹⁸F-fluorodeoxyglucose（FDG）accumulation on positron emission tomography（PET）scan has been proved to be a strong predictor of poor prognosis in DTC patients.However,the prognostic value of ¹⁸F-FDG PET/CT in ¹³¹I-avid（functioning pulmonary metastases）pulmonary metastases of DTC is not clear and was investigated in the study.Methods: DTC patients with ¹³¹I-avid PM treated with ¹³¹I between 2012 and 2016 were included.All the patients performed ¹⁸F-FDG PET/CT scans were retrospectively collected and analyzed.SUVmax（maximum standardized uptake value）,MTV（metabolic tumor volume）and TLG（total lesion glycolysis）were used to estimate the ¹⁸F-FDG uptake.Therapeutic response assessment was based on serum thyroglobulin（Tg）levels and tumor size on CT.The study was based on per-patient and per-lesion analyses.Results: ¹³¹I therapy was good response in 34 patients（34/42,81%）based on Tg.According to the RECIST（version 1.1）,38/42（90%）patients showed good response.In the 42 included patients,34（34/42,81%）showed ¹⁸F-FDG uptake which was defined as the abnormal foci（SUVmax >1.0）in the lungs.SUVmax,MTV and TLG and tumor size were the factors influencing the outcome of ¹³¹I treatment based on Tg（P=0.000,0.016,0.000,0.000）in perlesion analysis.There was a significant difference in response to ¹³¹I therapy between PM with F-I+ and F+/I+ both in the Tg evaluation and RECIST（version 1.1）（p= 0.044,0.001）according to per-lesion analysis.Conclusions: We concluded that higher ¹⁸F-FDG uptake and larger tumor size predicates poor therapeutic effect,high risk of disease progression in ¹³¹I-avid PM of DTC.Per-lesion analyses and quantitatively assessing the data of ¹⁸F-FDG PET/CT to predict ¹³¹I-avidity for pulmonary metastatic DTC would be more reliable than qualitative per-patient evaluation only.