Outcome of 309 patients with metastatic differentiated thyroid carcinoma treated with radioiodine

<jats:title>Abstract</jats:title><jats:p>From 1969 to 1990 there were 309 patients with differentiated thyroid carcinoma (241 papillary and 68 follicular) treated with radioactive iodine for functioning node metastases alone (<jats:italic>n</jats:italic>=191) or distant metastases (<jats:italic>n</jats:italic>=118) with or without node metastases. These patients represented 32.7% of 945 patients treated in our institution during the same period. Initial treatment included near‐total thyroidectomy and <jats:sup>131</jats:sup>I ablation of postsurgical thyroid residue, followed by L‐thyroxine suppressive therapy. At the end of follow‐up (mean 5.8 years), 146 patients (76.4%) in the group with nodal metastases were considered cured, as assessed by clinical and laboratory evaluation including whole body scan (WBS) and serum thyroglobulin (Tg) levels; 32 patients (16.7%) had persistent disease. Loss of <jats:sup>131</jats:sup>I uptake in persistent metastatic lesions occurred in five patients (2.6%), and newly developed distant metastases occurred in eight patients (4.2%). Of the patients with distant metastases, 36.4% were cured by <jats:sup>131</jats:sup>I. Distant metastases from papillary carcinomas had a higher cure rate than follicular carcinomas (<jats:italic>p</jats:italic><0.01). The metastases of four patients (5.2%) lost the property to take up radioiodine. Lung and bone metastases detectable by WBS but not by radiography were most likely to be cured by <jats:sup>131</jats:sup>I. The overall survival at the end of follow‐up was 95.8% in patients with only lymph node metastases and 76.0% in those with distant metastases. Tumor‐related deaths were 3.6% and 23.7%, respectively. Our data indicate that <jats:sup>131</jats:sup>I therapy is highly effective in the treatment of lymph node metastases from differentiated thyroid carcinoma. To a variable extent, distant metastases may also benefit from radioiodine therapy, definitive cure being much more likely during the early phase of metastatic involvement.</jats:p>