Objective: The objective of this clinical trial is to compare four strategies of management of postoperative radioiodine ablation in a 2×2 factorial design, each strategy combining a method of TSH stimulation and an activity of 131I. The primary endpoint is the rate of thyroid ablation.
Patients and methods: This multicentric, randomized, controlled, phase III trial involved 24 French centers, and compared 4 strategies for postoperative radioiodine ablation in a 2*2 factorial design: a method of TSH stimulation (either thyroid hormone withdrawal (THW) or rhTSH (Thyrogen, Genzyme)) and an activity of 131I (either 1.1 or 3.7 GBq). Study patients met the following criteria: age >18 years; total thyroidectomy for differentiated papillary or follicular (no aggressive histology) thyroid carcinoma, between 30 and 120 days before randomization, treatment with L-T4 for at least one month; TNM stage pT1<1 cm, N1 or Nx, pT1>1 cm (any N) or pT2, N0; absence of distant metastasis, no iodine contamination. Thyroid ablation was assessed at 610 months after radioiodine ablation with rhTSH stimulated Tg determination and neck-US; whole-body scan was performed in case of positive Tg antibodies (TgAb). The comparison between the four strategies is based on equivalence framework, with two-side α=0.05.
Results: Seven hundred and fifty-three patients who gave written informed consent were included in the study between April 2007 and February 2010 and currently data on radioiodine ablation are available for 693 patients (92%) who form the basis of the present report: 79% were females, mean age was 49 years, and 90% had papillary cancer; 30% of tumors were pT1N0, 17% were pT1N1, 39% were pT1, Nx and 12% were pT2, N0. Mean time between thyroidectomy and randomization was 50 days, and mean time between randomization and radio-iodine ablation was 39 days. Data on the follow-up control are currently available for 477 patients. Neck-US was normal in 444 patients (93%) and suspicious or abnormal in 33 (7%). Stimulated Tg level was >1.0 ng/ml in 25 (5%) patients and 31 patients had TgAb. Thyroid ablation was considered complete in 417 patients (87%), incomplete or doubtful in 58 patients (12%) and non-evaluable in 2 patients.
Conclusion: These data will be updated for the ECE meeting, and results of ablation will be presented.
30 Apr - 04 May 2011
European Society of Endocrinology