- Metastatic, RAI refractory, differentiated thyroid cancer (including papillary and follicular thyroid cancer and their sub-types such as Hurthle cell thyroid cancer as well as poorly differentiated thyroid cancer), with progression within 13 months prior to study registration. RAI refractoriness is defined as absence of uptake of RAI on either a low-dose diagnostic test or a post-treatment RAI scan in measurable lesions or radiographic progression of disease within 12 months of the last course of RAI treatment despite the recorded uptake of RAI with that previous therapy or having a cumulative lifetime administered dose of greater than 600mCi.