Crucial Role of Iodine 131 in the Management of Bone Metastasis of Differentiated Thyroid Cancer

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Introduction: To determine the role of Iodine 131 in the management of bone metastasis of differentiated thyroid cancer.

Methods: This is a retrospective study including 109 patients with bone metastasis of differentiated thyroid cancer (DTC) with a regular follow-up at the Department of Nuclear Medicine of CHU Bab El Oued. Those 29 men and 90 women with an average age of 52 years (range from 20 to 70 years) presented bone metastasis of DTC with the following pathological variants: 71 follicular (pure or variant forms), 27 papillary (21 pure and 12 variants), and 11 indeterminate. From the 109 patients, bone metastasis was the onset of DTC in 43 patients and discovered during the follow-up in 66 patients. Bone metastases were associated with metastasis in other parenchymal sites in 69 patients (including 47 in lungs). The most common site of bone metastasis was the pelvis (42 patients) followed by spine (39 patients) then skull (26 patients). All patients were treated with radio iodine, 49 alone and 66 in association with other therapeutic modalities (surgery, external radiotherapy, and targeted chemotherapy).

Results: A total of 101 patients received at least 11GBq with a global average of 18GBq. For those patients who were treated by ¹³¹I only (57), the average of cumulative dose was little bit inferior than those patients who received an additional therapy (52) for their bone metastasis (16GBq vs. 20GBq). During the follow-up no serious complication observed with ¹³¹I treatment in 101 patients. Intrinsic stimulation alone was used in 57 patients and associated with recombinant TSH in 52 patients. In total, 83 patients of 101 were well stabilized during 4 years by radio iodine and 56 patients have had a survival of more than 5 years and 23 patients a survival more than 10 years survival. In addition, 66% of patients are still stable and well controlled by radio iodine alone or associated with surgery and external radiotherapy. Eight refractory cases for radio iodine were noted and have been referred to oncology for targeted or general chemotherapy. However, we have had 23 patients died and 12 patients died for other reasons not linked to direct complications of the metastasis diseases.

Conclusion: Radio iodine treatment of bone metastasis under intrinsic alone or associated with external stimulation is a safe therapy for bone metastasis of differentiated thyroid cancer. However, active surveillance for at least two times per year is strongly recommended to assess regularly the progress of bone metastasis and decide for another iterative dose of ¹³¹I or for another complementary therapy.

Publication History

Article published online:
25 May 2023