Judicious use of recombinant TSH in the management of differentiated thyroid carcinoma.

Objective: To evaluate the feasibility of using recombinant human TSH (rhTSH) in conjunction with ¹³¹I to treat patients with differentiated thyroid carcinoma.

Methods: Between July 2003 and April 2009, 14 patients [mean age, 39.1 years (range 14-71 years)], of whom seven were treated for remnant ablation and seven for irresectable or metastatic disease, received rhTSH-aided ¹³¹I therapy. None had an adequate rise in TSH. The mean ¹³¹I dosage administered was 5206.3 MBq. Baseline thyroglobulin/anti-thyroglobulin (Tg/anti-Tg) and TSH levels were documented. rhTSH (0.9 mg) was given intramuscularly on days 1 and 2, and TSH levels were recorded. ¹³¹I was given when the TSH level rose to >30 μIU/ml. Tg/anti-Tg levels were measured at 3-month intervals. A ¹³¹I whole-body scan (¹³¹I scan) was performed 6 or 12 months after treatment.

Results: The baseline median valid Tg and TSH levels were 76.2 ng/ml (range 14.1 to >30000) and 3.63 μIU/ml (range 1.36-11.0), respectively. The rise in TSH level was 34.8-96.9 μIU/ml after the first rhTSH injection and 33.1 to >75 μIU/ml after the second injection. The post-therapy ¹³¹I scan showed uptake at disease sites in all patients, indicating the initial empirical adequacy of treatment. Follow-up ¹³¹I scan was positive for four patients, but negative for three of these patients after subsequent therapy. Complete resolution of disease was seen in eight patients and partial resolution in four after 3 months of therapy; one had stable disease; and in one patient with progressive disease, complete resolution was achieved after repeated ¹³¹I doses with thyroxine withdrawal. After a median follow-up of 39.2 months, all patients were alive and no disease recurrence was observed. The overall response rate at 3 months was 86% and had improved to 93% at the time of this review. The final ablation rate in seven patients was 100%. Apart from notable neck swelling in four patients, which was responsive to medication, and headache in two patients, no significant short-term side-effects of therapy were seen.

Conclusion: In our setting, the use of rhTSH-aided ¹³¹I ablation and treatment was safe and effective.