Embolization in combination with radioiodine therapy for bone metastases from differentiated thyroid carcinoma

The outcome for patients with bone metastases from differentiated thyroid carcinoma is worse compared to the overall prognosis of patients with differentiated thyroid carcinoma. The aim of this study is to evaluate the effect of embolization with concomitant radioiodine treatment on the serum thyroglobulin (Tg) level, pain and neurological symptoms in patients with large bone metastases from differentiated thyroid carcinoma.

Five symptomatic patients, who presented with a large unresectable bone metastasis of differentiated thyroid carcinoma were treated with radioiodine and embolization. The effect of this combined treatment was compared to the effect of radioiodine without embolization in a previously treated control group of 6 patients. Serum Tg levels, pain and neurological symptoms were scored. Both groups were treated similarly with total thyroidectomy followed by ablation with 5.55 GBq 131I and a second dose of 5.55 GBq 131I three months later, except for embolization in the embolization group, which took place between the 2 radioiodine treatments.

In the embolization group, serum Tg at the second 131I therapy had decreased by 88.7% (median, range: 77.1-99.3%), which was significantly more compared to the decrease of serum Tg in the control group (18.6%, range: -4.7-95%, P < 0.05). CT-scanning showed a median volume reduction of the metastasis after radioiodine treatment combined with embolization of 52.5% (range: 39-80%). Both strategies resulted in a rapid relief of pain and neurological symptoms. Embolization was not accompanied with severe complications.

This preliminary study suggests that embolization of bone metastases of differentiated thyroid carcinoma in combination with radioiodine treatment results in a significant initial reduction of serum Tg level compared to radioiodine treatment alone. This suggests a beneficial reduction in tumour burden. In this patient category, embolization appears to be a safe and well tolerated procedure.