• Proportion of patients with successful remnant ablation at 6-8 months [ Designated as safety issue: No ]
  
• Relative risk of having a successful remnant ablation [ Designated as safety issue: No ]
  

• Quality of life as measured by the SF-36 questionnaire at baseline, the day of ablation, and at 3 months [ Designated as safety issue: No ]
  
• Locoregional recurrence [ Designated as safety issue: No ]
  
• Distant metastases [ Designated as safety issue: No ]
  
• Survival [ Designated as safety issue: No ]
  
• Incidence of second primary malignancy [ Designated as safety issue: No ]
  

OBJECTIVES:

Primary

• Compare the percentage of successful remnant ablation at 6-8 months after administration of high- vs low-dose iodine I 131 with vs without recombinant thyroid-stimulating hormone in patients who have undergone total thyroidectomy for differentiated thyroid cancer.

Secondary

• Compare quality of life in patients treated with these regimens.
• Compare locoregional recurrence in patients treated with these regimens.
• Compare distant metastases, survival, and incidence of second primary malignancies in patients treated with these regimens.

OUTLINE: This is a multicenter, factorial, randomized study. Patients are stratified according to treatment center and disease stage (I vs II vs III vs IVA). Patients are randomized to 1 of 4 treatment arms.

Patients receive thyroid hormone replacement therapy (THRT)* with thyroxine (T4)** or liothyronine sodium (T3). Patients randomized to arm III or IV discontinue THRT 4 weeks (for patients receiving T4) or 2 weeks (for patients receiving T3) prior to remnant ablation.

NOTE: *Some treatment centers may chose to avoid starting THRT in patients randomized to arm III or IV.

NOTE: **Patients receiving T4 may be switched to T3 for 2 more weeks before discontinuing THRT.

• Arm I: Patients receive recombinant thyroid-stimulating hormone (rTSH) intramuscularly on days 1 and 2 and undergo remnant ablation with low-dose iodine I 131 on day 3.
• Arm II: Patients receive rTSH as in arm I and undergo remnant ablation with high-dose iodine I 131 on day 3.
• Arm III: Patients undergo remnant ablation with low-dose iodine I 131 as in arm I.
• Arm IV: Patients undergo remnant ablation with high-dose iodine I 131 as in arm II.

Quality of life is assessed at baseline, day 3 before remnant ablation, and at 3 months.

After completion of study therapy, patients are followed at 3 months, between 6-8 months, and then annually thereafter.

Peer Reviewed and Funded or Endorsed by Cancer Research UK

PROJECTED ACCRUAL: A total of 468 patients will be accrued for this study.