The Association Between The Interval of Radioiodine Treatment and The Response and Adverse Effect in Patients with Non-Progressive Lung Metastases From Differentiated Thyroid Cancer

Abstract Purpose To assess the association between the interval of radioiodine treatment (RT) and short-term response and adverse effects in patients with non-progressive lung metastases from differentiated thyroid cancer (DTC). Methods A total of 147 neighboring RT course pairs from 78 patients with 131 I-avid non-progressive lung metastases from DTC were retrospectively analyzed. The courses were categorized into two groups by interval of neighboring therapeutic 131-I administrations (≤12 months and >12 months). The short-term therapy response and adverse effects of the two groups were evaluated. Results No significant differences were found between the two groups in the change rate of thyroid stimulating hormone (TSH) stimulated serum thyroglobulin (ΔsTg%) (P=0.806) or the change rate of metastasis lesion long diameter (ΔLLD%) (P=0.246). In the subanalysis considering the number of treatments (3 and >3 times), no significant difference was found (P>0.05). No difference was found in biochemical response (interval ≤12m: P=0.325, interval >12m:P=0.456) or structural response (interval ≤12m: P=0.760, interval >12m: P=0.563) between the former and latter courses with regard to different intervals. No difference was found in adverse events between former and latter courses with regard to different intervals (P>0.05). Conclusions The interval of RTs is not associated with the short-term response or adverse effects in patients with non-progressive lung metastases from DTC. Appropriately prolonging the interval in specific patients seems to be feasible, and the interval of RT should be individually managed in clinical practice.