Thyroid remnant ablation in differentiated thyroid cancer: searching for the most effective radioiodine activity and stimulation strategy in a real-life scenario.

Abstract

Differentiated thyroid cancer is rare, but the incidence has been increasing in the last few decades. Early treatment is based on surgery and thyroid remnant ablation (TRA) by means of radioiodine therapy. Despite radioiodine being widely used for decades, the choice of ablative activity is generally empirical and no consensus has been reached to date. The aim of our study was to compare the efficacy and safety of different radioiodine activities. In addition, we compared the ablation rate in patients treated in the hypothyroid state or after recombinant human thyroid-stimulating hormone (rhTSH) administration, retrospectively reviewing the records of 471 patients affected by differentiated thyroid cancer. Patients were subdivided into three groups on the basis of the different activities of radioiodine administered and taking into account the different approaches used to perform the therapy: thyroid hormonal withdrawal or rhTSH stimulation. The success of TRA was evaluated 12 months later. TRA was obtained in 62/79 (78.5%) in group A (1110 MBq in the hypothyroid state), 183/190 (96.3%) in group B [2220 MBq in the hypothyroid state or after rhTSH administration: 87/90 (97%) and 96/100 (96%) patients, respectively], 199/202 (98.5%) in group C [3700 MBq in hypothyroid state or after rhTSH administration: 98/100 (98%) and 101/102 (99%) patients, respectively]. Our data demonstrate that 2220 and 3700 MBq radioiodine are more effective compared with 1110 MBq in TRA, without significant differences between 2220 and 3700 MBq or between hypothyroidism and euthyroidism. We suggest rhTSH-aided TRA with 2220 MBq iodine-131, as this approach permits efficacious treatment, thereby reducing side effects, absorbed dose to body and hospital stay.