- Patients must have histologically or cytologically confirmed papillary, follicular, or Hurthle cell carcinoma (cohort A) or medullary thyroid carcinoma (cohort B); their disease must have progressed despite treatment with iodine-131 therapy or they are not candidates for iodine-131 therapy and their disease cannot be completely removed by surgery; all patients with WDTC are expected to be on thyroxine suppression therapy