Few reports have examined the use of recombinant human thyroid-stimulating hormone (rhTSH) for ablation of postsurgical thyroid remnants after low-dose radioactive iodine (RI) therapy, compared with conventional thyroid hormone withdrawal. We investigated whether patient preparation using rhTSH was comparable to conventional thyroid hormone withdrawal with respect to efficacy of postsurgical remnant ablation in low-risk patients receiving a 30 mCi RI. In addition, we also evaluated the impact of rhTSH (rhTSH vs. conventional thyroid hormone withdrawal) on quality of life (QoL) of thyroid cancer patients undergoing RI ablation.
This study included three groups of patients, enrolled consecutively. From February 2006 to March 2007, 291 patients were enrolled and randomized, after total thyroidectomy: (1) withdrawal of levothyroxine (LT4) for 4 weeks (T4-WD Group, n = 89), (2) withdrawal of LT4 for 4 weeks plus 2 weeks on and then 2 weeks off liothyronine (LT3) (T3-WD Group, n = 133), and (3) rhTSH administration (rhTSH Group, n = 69). QoL was determined at the time of ablation.
Patients in the three groups did not differ significantly in baseline characteristics or tumor, node and metastasis (TNM) staging. In all study groups, serum TSH levels showed very good stimulation (mean, 82.24 +/- 18.21 mU/L), without significant between-group differences (p = 0.5213). Follow-up examinations were performed 12 months after ablation to assess ablation outcome in each group by 131 whole body scans (WBSs), serum thyroglobulin measurement after TSH stimulation, and neck ultrasonography. The successful ablation rate was 91.0% in T4-WD Group, 91.7% in T3-WD Group, and 91.3% in rhTSH Group, without significant between-preparation differences (p = 0.2061). QoL was better preserved in rhTSH Group than in T4-WD and T3-WD Groups (p < 0.0001). However, there was no QoL difference at the time of ablation between T4-WD and T3-WD Groups.
Our study indicates that use of rhTSH preserves QoL in patients undergoing RI ablation and affords an ablation success rate comparable to that seen after thyroid hormone withdrawal. Notably, ablation preparation using withdrawal of LT3 for 2 weeks did not prevent development of profound hypothyroidism, as also occurred when LT4 alone was withdrawn for 4 weeks.