NEW YORK (Reuters Health) – Most patients with differentiated thyroid cancer metastasized to bone benefit from iodine-131 therapy, with stabilization of disease and significant reduction in pain, a Chinese team reports in the Journal of Clinical Endocrinology and Metabolism for October.

Iodine-131 has been used to treat differentiated thyroid cancer (DTC) for 70 years, the authors note, but very few studies have evaluated I-131 therapy for DTC bone metastases. “The indolent course of DTC requires very large cohorts of patients followed over several decades to confirm significant differences in prognostic factors and treatment efficacy,” they explain “Moreover, DTC patients with bone metastasis are relatively rare.”

Dr. Quan-Yong Luo and colleagues at Shanghai Sixth People’s Hospital, Shanghai Jiao Tong University, therefore retrospectively studied outcomes of 106 such patients treated at their center. The patients received oral I-131 therapy up to 13 times at intervals of 4 to 12 months. They were followed for 1 to 17 years, with the median being 10.5 years.

Based on the change in serum thyroglobulin, I-131 treatment significantly decreased disease activity in 37 cases (34.9%) and stabilized it in 56 patients (52.8%), the team reports. Treatment also produced significant relief of pain in 39 of 61 patients (63.9%) with painful bone metastases, they found.

Survival rates were 86.5% at 5 years and 57.9% at 10 years, Dr. Luo and colleagues report. They found that factors independently associated with better prognosis were a solitary bone metastasis, the absence of non-osseous metastases, and bone surgery prior to I-131 therapy.

“In summary,” they write, “I-131 therapy can significantly decrease or stabilize serum Tg (thyroglobulin) and alleviate bone pain. It can also shrink or stabilize lesions for most DTC patients with bone metastases, and therefore, it is an effective treatment modality for bone metastases from DTC.”

Reference:
Efficacy and Survival Analysis of 131I Therapy for Bone Metastases from Differentiated Thyroid Cancer
J Clin Endocrinol Metab 2011;96.