Radioiodine refractory differentiated thyroid cancer.

Differentiated thyroid cancer is composed of papillary (85%), follicular (13%) with their subtypes and anaplastic (<2%) thyroid cancer, derived from follicular dedifferentiation. In the majority of cases (85%), treatment is succeeded with thyroxine suppression and radioiodine ablation. However, there is a small percentage of patients presenting with local recurrence or metastases during follow up. In such cases, reoperation and radioiodine treatment are the treatments of choice. 10% of the aforementioned patients appear resistance to radioiodine treatment and they are considered refractory to iodide. As refractory to radioiodine is defined a patient who fulfills one of the following criteria: 1. Negative RAI Uptake 2. RAI uptake in some but not all metastases 3. Disease progression 6-12 months after Radioiodine ablation 4. Disease progression after radioiodine treatment more of than 600mCi.