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The Dose of Radioactive Iodine Needed to Ablate the Thyroid Remnant Left Behind After Thyroidectomy

This study is ongoing, but not recruiting participants.
Helsinki University Central Hospital
Information provided by (Responsible Party):
Hanna Mäenpää, Helsinki University Identifier:
First received: June 26, 2005
Last updated: March 18, 2016
Last verified: March 2016
The thyroid cells take up iodine, and radioactive iodine is commonly used to irradiate residual thyroid tissue and thyroid cancer following surgical removal of the thyroid gland (thyroidectomy). A whole body radioactive iodine scanning is usually carried out after thyroidectomy to assess the amount of thyroid tissue left behind at surgery (that might still contain cancer), and to evaluate the presence of iodine avid lesions elsewhere in the body (that might be cancer metastases). A large dose of radioactive iodine is often given, still the optimal iodine dose to ablate the thyroid remnant after surgery is not known. In this study, two radioactive iodine doses are compared in the ablation of the thyroid remnant, a smaller (1110 MBq) dose and a larger (3700 MBq) dose. The study participants are randomly allocated using a 1:1 ratio to receive either the smaller or the larger radioactive iodine dose. These treatments are compared for safety, adverse effects, and the need for subsequent repeat treatments. The individual absorbed radiation doses are measured. The study hypothesis is that fewer repeat radioiodine treatments might be needed after the larger dose, but the larger dose might be associated with a higher frequency of adverse events.

Condition Intervention Phase
Thyroid Neoplasms
Drug: Radioactive iodine
Phase 3

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Open Label
Primary Purpose: Treatment
Official Title: Effect of the Radioiodine Dose in Thyroid Ablation- A Randomized Comparison of 1110 MBq to 3700 MBq

Resource links provided by NLM:

Further study details as provided by Helsinki University:

Primary Outcome Measures:
  • Cumulative number of radioactive iodine administrations [ Time Frame: 15 yrs ]

Secondary Outcome Measures:
  • Adverse events [ Time Frame: 15 yrs ]
  • Absorbed radiation dose [ Time Frame: 15 yrs ]
  • Cancer recurrence [ Time Frame: 15 yrs ]

Enrollment: 160
Study Start Date: January 2000
Estimated Study Completion Date: September 2020
Primary Completion Date: October 2004 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Radioactive iodine 1,1 GBq
Low activity of radioiodine, 1,1 GBq
Drug: Radioactive iodine
Radioiodine is radionuclear treatment given in oral capsules in two activies 1,1 and 3,7 GBq
Other Name: radioiodine
Radioactive iodine 3,7 GBq
Routine activity of radioiodine, 3,7 GBq
Drug: Radioactive iodine
Radioiodine is radionuclear treatment given in oral capsules in two activies 1,1 and 3,7 GBq
Other Name: radioiodine

Detailed Description:

The study participants are randomly allocated to receive either a 1110 MBq or a 3700 MBq dose of radioiodine (131I) approximately 5 weeks after thyroidectomy. Thyroxin substitution is initiated only after administration of radioactive iodine. Treatment efficacy is monitored using serum thyroglobulin measurements and whole body radioiodine scanning. The absorbed radiation dose at the thyroid remnant and the biological half-life of radioactive iodine are measured with SPECT, 131I iodine detector and a Geiger counter.

Treatment related adverse events are collected using structured forms 4 to 5 days, 2 weeks and 3 months after administration of radioiodine. The need for a repeat treatment is assessed 4 to 6 months after the first administration of radioiodine. The criteria for a repeat radioiodine treatment are serum thyroglobulin > 1 ug/L and/or presence of abnormal radioiodine uptake in a whole body radioiodine scanning, which is carried out following a 4-week interruption of thyroxin supplementation or following administration of rhTSH.

Number of patients: 160

Aims of the study:

  • To find out weather the risk for second radioiodine treatment differs with two dose levels of radioiodine: 1110 MBq or 3700 MBq.
  • To study possible differences in the adverse effects in the treatment groups. Also days at hospital are counted.
  • To analyse the effect of absorbed radiation dose to the treatment results

Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion criteria:

  • Total or near total thyroidectomy performed for papillary or follicular thyroid cancer
  • R0-1 resection, no macroscopic cancer left behind at surgery
  • Physically and emotionally able to undergo radioiodine treatment
  • A written informed consent

Exclusion criteria:

  • Pregnancy
  • Physical or psychiatric illness that may deteriorate during the isolation period required by radioiodine therapy
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Please refer to this study by its identifier: NCT00115895

Helsinki University Central Hospital, Department of Oncology
Helsinki, Finland, FIN-00029HUS
Sponsors and Collaborators
Helsinki University
Helsinki University Central Hospital
Principal Investigator: Hanna O Mäenpää, M.D. Ph.D. Deputy Chief Physician
  More Information

Additional Information:
Publications automatically indexed to this study by Identifier (NCT Number):
Responsible Party: Hanna Mäenpää, Chief of Department, Helsinki University Identifier: NCT00115895     History of Changes
Other Study ID Numbers: SYTJ001T/2000
Study First Received: June 26, 2005
Last Updated: March 18, 2016

Keywords provided by Helsinki University:
serum thyroglobulin
whole body radioiodine scanning

Additional relevant MeSH terms:
Thyroid Diseases
Thyroid Neoplasms
Endocrine System Diseases
Endocrine Gland Neoplasms
Neoplasms by Site
Head and Neck Neoplasms
Cadexomer iodine
Anti-Infective Agents, Local
Anti-Infective Agents
Trace Elements
Growth Substances
Physiological Effects of Drugs processed this record on April 21, 2017