Whole-body effective half-life of radioiodine in children and young adults with papillary thyroid cancer
摘要
The lack of radioiodine-131 (RAI) kinetic study is a serious challenge for rational dosing for children and young adults (CYAs) with papillary thyroid cancer (PTC). The present study was conducted to investigate the whole-body effective half-life (EHL) and absorbed dose in RAI ablative therapy of CYAs with PTC.
MethodsIn the period 2017–2022, all consecutive PTC patients 20 years or younger prepared for ablative RAI therapy after thyroid hormone withdrawal were prospectively recruited. Serial whole-body dose-rate measurements after administration were performed to deduce whole-body RAI retention. Calculations based on the deduced whole-body retention and the schema of Medical Internal Radiation Dosimetry were derived to determine whole-body EHL and absorbed doses. A multivariate linear regression analysis was employed to assess the association between whole-body EHL and potential predictors.
ResultsA total of 52 patients (median age 17 years [range, 6–20 years]) were recruited. The mean whole-body EHL (±SD) was 10.3 (3.3) hours (median, 9.4 h [range, 6.3–21.7 h]). In univariable linear regression analysis, whole-body EHL was significantly associated with gender, body surface area (BSA) and body mass index (p < 0.05). Creatinine, Cystatin C, glomerular filtration rate (GFR) and positive post-ablation scintigraphy approached significance with respect to EHL (p ≤ 0.2 and ≥0.05). At multivariable analysis, BSA, GFR and positive post-ablation scintigraphy was associated with EHL. A median activity of 3.7 GBq of RAI (range, 1.85–7.40 GBq) was administered and a median whole-body absorbed dose of 0.22 Gy was delivered (range, 0.11–0.79 Gy).
ConclusionA wide variation of whole-body EHL was observed in CYAs with PTC treated with RAI. The whole-body EHL is significantly longer in CYAs with larger BSA, decreased GFR and presence of extra-thyroidal disease. Understanding these predictors may improve our ability to dosing strategies in RAI therapy of CYAs with PTC.