Long‐Term Outcome of Low‐ and High‐Dose Radioiodine for Thyroid Remnant Ablation

ABSTRACT Objective We conducted a prospective randomized clinical trial to compare the efficacy of low‐ and high‐dose radioiodine for remnant ablation in patients with low‐risk differentiated thyroid cancer (DTC) in China. The first‐stage results showed equivalence was observed between the two groups. Here, we report recurrence and survival at 3–5 and 6–10 years and biochemical parameters. Design, Patients and Methods Between January 2013 and December 2014, adult patients with DTC were enroled. Patients had undergone total or near‐total thyroidectomy, with or without cervical lymph node dissection, with tumour stages T1–T3 with or without lymph node metastasis, but without distant metastasis. Patients were randomly assigned to the low‐dose (1850 MBq) or high‐dose (3700 MBq) radioiodine group. They were then followed up for 3–5 and 6–10 years. Data on biochemical abnormalities, recurrence and survival were analysed using Kolmogorov–Smirnov and χ 2 tests. Results The data of 228 patients (mean age = 42 years; 70.6% women) were analysed, with 117 patients in the low‐dose group and 111 in the high‐dose group. There were no significant differences in biochemical abnormalities, recurrence, or survival rates at the 6–10‐year follow‐up (all p > .05). Nine patients experienced recurrence in the low‐dose group (8.7%), while eight patients experienced recurrence in the high‐dose group (8.2%). The survival rates were 100% and 98.2% in the low‐ and high‐dose groups, respectively. Conclusions The long‐term effectiveness and safety of low‐dose (1850 MBq) radioiodine are the same as those of high‐dose (3700 MBq) radioiodine for thyroid remnant ablation in Chinese patients with low‐risk DTC.