Comparisons of thyroid hormone withdrawal and rhTSH aided 1850 MBq and 3700 MBq radio iodine (RAI) post-surgical remnant ablation in differentiated thyroid cancer (DTC)

206 Objectives To compare the successful thyroid remnant ablation rate of 1850 MBq and 3700 MBq 131I prepared with thyroid hormone withdrawal (THW) and recombinant human thyroid stimulating hormone (rhTSH) in patients with DTC. Methods 732 DTC patients after total/near total thyroidectomy were consecutively assigned to the 3 treatment groups: in the 1st group, patients (n =218) were ablated with 1850 MBq RAI after THW; in the 2nd group, patients (n =141) were ablated with 3700 MBq RAI after THW; in the 3rd group, patients (n =373) were ablated with 1850 MBq RAI after rhTSH. The outcome of thyroid remnant ablation was retrospectively compared by conventional 131I scan and/or serum thyroglobulin (Tg) in the absence of Tg-antibody performed under TSH stimulation 2-27 months after ablation. Results At the first follow-up, Tg Conclusions 1850 MBq RAI after THW or rhTSH is equally effective as 3700 MBq after THW for thyroid remnant ablation in DTC patients. 1850 MBq RAI under rhTSH is recommend for post-surgical ablation and is safe, effective and avoids hypothyroidism. Research Support Alberta Cancer Foundation, Canada Foundation for Innovatio