[Distant metastasis of differentiated thyroid cancers. Diagnosis by 131 iodine (I 131) and treatment]

Distant metastases in differentiated thyroid cancer involve mainly lung and bone. Lung metastases were found in 5% of papillary forms and 10% of follicular forms respectively. I 131 uptake was found in 55% of the cases irrespective of histology. Bone metastases were found in 20% of follicular and 3.5% of papillary forms, respectively. Ablation of post-operative thyroid remnants is obtained by administering 3.7 GBq 1 131; I 131 (.2 to .4 GBq) is then used to localize distant metastases and a further 3.7 to 7.4 GBq is administered for therapy. Results are good in lung metastases, with a survival of 72% at 5 years. Bone metastases cannot be cured with I 131 alone. Surgery is indicated as a first line therapy if possible. In order to reduce the vascularization of the metastase a pre-operative embolization should be attempted. After bone surgery a therapeutic dose of I 131 is given if a post-operative 1 131 uptake is found. Others treatments of bone metastases are palliative surgery, external radiotherapy, cementing of the metastases.