NEW YORK (Reuters Health)- When differentiated thyroid cancer has spread to bone, iodine-131 can help stabilize the disease and significantly reduce pain, a Chinese team reports.
Iodine-131 has been used to treat differentiated thyroid cancer (DTC) for 70 years, the authors note, but it's been very difficult to evaluate its effect on 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," said Dr. Quan-Yong Luo and colleagues at Shanghai Sixth People's Hospital. "Moreover, DTC patients with bone metastasis are relatively rare."
In a report scheduled for the October print issue of the Journal of Clinical Endocrinology and Metabolism, available online now, the researchers report on 106 such patients treated at their center with oral I-131 therapy, up to 13 times at intervals of 4 to 12 months. Follow-up ranged from 1 to 17 years, with the median being 10.5 years.
Based on changes in serum thyroglobulin, I-131 significantly decreased disease activity in 37 cases (34.9%) and stabilized it in 56 patients (52.8%), the team reports.
Treatment also produced significant pain relief in 39 of 61 patients (63.9%) with painful bone metastases.
Survival rates were 86.5% at 5 years and 57.9% at 10 years, Dr. Luo and colleagues report. 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, 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," they write.
J Clin Endocrinol Metab 2011.