High Dose vs Low Dose I 131 +/- rhTSH for Differentiated Thyroid Cancer

Multicentre Randomised Trial of High Dose Versus Low Dose Radioiodine, With or Without Recombinant Human Thyroid Stimulating Hormone, for Remnant Ablation Following Surgery for Differentiated Thyroid Cancer [HILO]

RATIONALE: Radioactive iodine uses radiation to kill tumor cells. Giving iodine I 131 with or without thyroid-stimulating hormone after surgery may kill any tumor cells that remain after surgery. It is not yet known which dose of iodine I 131 is more effective when given with or without thyroid-stimulating hormone in treating thyroid cancer.

PURPOSE: This randomized phase III trial is studying two different doses of iodine I 131 to compare how well they work when given with or without thyroid-stimulating hormone in treating patients who have undergone surgery for thyroid cancer.

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.

DISEASE CHARACTERISTICS:

• Histologically confirmed differentiated thyroid cancer

  • T1-T3, Nx, N0, N1, M0 disease

• Has undergone one- or two-stage total thyroidectomy with or without lymph node dissection

  • All known tumor resected (R0)

• Requires radioiodine remnant ablation

  • Does not require mandatory recombinant thyroid-stimulating hormone

• No Hurthle cell carcinoma or aggressive variants, including any of the following:

  • Tall cell, insular, poorly differentiated disease with diffuse sclerosing
  • Anaplastic or medullary carcinoma

PATIENT CHARACTERISTICS:

• WHO performance status 0-2

• No severe comorbid conditions including, but not limited to, any of the following:

  • Unstable angina
  • Recent heart attack or stroke
  • Severe labile hypertension
  • Dementia
  • Concurrent dialysis
  • Tracheostomy needing care
  • Learning difficulties
  • Inability to comply with radiation protection issues
  • Requirement for frequent nursing or medical supervision that puts staff at risk for unacceptable radiation exposure

• No other cancers except basal cell skin cancer or carcinoma in situ of the cervix

• Not pregnant or nursing

• Negative pregnancy test

• Fertile female patients must use effective contraception during and for 6 months after radioiodine remnant ablation

• Fertile male patients must use effective contraception during and for 4 months after radioiodine remnant ablation

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• More than 3 months since prior contrast CT scan
• No prior iodine I 131 or iodine I 123 pre-ablation scan
• No prior treatment for thyroid cancer (except surgery)