The aim of the study was to investigate whether recombinant human thyroid-stimulating factor (rhTSH) is effective for the radiometabolic ablation of post-surgery thyroid remnants in low-risk thyroid cancer compared to thyroid hormone withdrawal.
The study compared two groups of patients: group 1 consisted of 145 patients with differentiated thyroid cancer (127 papillary cancer and 18 follicular cancer), who received 131I for post-surgical remnants ablation (mean 1,37 GBq or 37 mCi) with the aid of rhTSH; and group 2 consisted of 106 patients with the same histological features (96 papillary cancer and 10 follicular), who received similar amount of radioiodine (1,58 GBq or 43 mCi) in the hypothyroid state after thyroid hormone withdrawal. All patients underwent a total thyroidectomy and could be considered at low-risk of recurrences (stage I and II).
In both groups, serum TSH reached a very good stimulation level [58-100 U/liter (mean 98) in group 1 and 10-100 U/liter (mean 67) in group 2, respectively]. At the first whole body scintigraphy (WBS) after 131I treatment, all patients showed thyroid remnants and only four patients of the first group and three patients of the second group showed lymph node metastases. After 1 year both groups were studied by using neck ultrasound, WBS and/or measuring Thyroglobulin after rhTSH stimulation or after thyroid hormone withdrawal. The percentage of ablation was equivalent between the two groups: 93% in group 1 and 92% in group 2 and Tg was undetectable in 86% of first group and 87% of second group. 3 patients of group 1 and 8 patients of group 2 underwent a new radioiodine therapy for the presence of recurrences.
Our findings indicate that the administration of rhTSH has resulted in an ablation rate similar to that of thyroid hormone withdrawal for low-risk differentiated thyroid cancer patients and low doses of 131I have the same effectiveness of higher.