Radioactive Iodine Treatment and External Radiotherapy for Lung and Bone Metastases from Thyroid Carcinoma

We assessed the therapeutic benefits of ¹³¹I treatment in patients with distant metastases of differentiated thyroid carcinoma. Methods: Of 2200 patients treated for differentiated thyroid carcinoma at our institution, 394 had lung and/or bone metastases. Results: Two-thirds of the patients had ¹³¹I uptake in their metastases, but only 46% achieved a complete response. Prognostic factors for complete response were: younger age, presence of ¹³¹I uptake in the metastases and small extent of disease. The survival rate was 33% at 15 yr. As shown by multivariate analysis, favorable prognostic factors for survival were: younger age and time of metastases detection, well-differentiated histologic type of the thyroid tumor, presence of ¹³¹I uptake in the metastases, small extent of the disease and year of discovery of metastases. Conclusion: In terms of survival, the benefits of ¹³¹I therapy cannot be demonstrated by prospective controlled studies. The present study clearly demonstrates, however, that treatment with ¹³¹I is one of the factors which accounts for survival; patients whose metastases concentrated ¹³¹I and who could be treated with radioiodine had higher survival rates. Patients who achieved complete response following treatment of distant metastases had a 15-yr survival rate of 89%, while those who did not achieve complete response had a survival rate of only 8%. The survival rate improved with the year of discovery of distant metastases, after ¹³¹I total-body imaging and serum thyroglobulin measurements were routinely used.