Differentiated Thyroid Cancer: is There a Need for Radioiodine Ablation in Low Risk Patients?

Inclusion criteria

• Patients with differentiated thyroid cancer (papillary, follicular or with Hurthle cells) in the absence of aggressive histological subtypes (poorly differentiated, tall-clear-cylindric cell, diffuse sclerosing or with an anaplastic component)
• Patients having undergone a total thyroidectomy with complete (R0) tumor resection, with or without lymph node neck dissection
• Total thyroidectomy performed 2 to 5 months before inclusion
• Patients with low risk of recurrence: pT1amN0 or pT1amNx with a sum of the size of the lesions above 1 cm and equal to or less than 2 cm, or pT1bN0 or pT1bNx (TNM 2010 classification).
• Post-operative neck ultrasound (performed 2 to 5 months after surgery) showing the absence of abnormalities in the lateral lymph node compartments, or if abnormalities, no lymph nodes with abnormal cytology and/or thyroglobulin concentration in the aspirate fluid > 10 ng/mL
• Age >=18 years
• Performance status of 0 or 1
• Patients who signed the informed consent
• Patients who can be followed-up annually during 5 years in order to assess the objectives of the study
• Women of childbearing age should have a negative pregnancy test before any radioiodine administration
• Both patients with or without thyroglobulin antibodies are eligible

Exclusion criteria

• Patients having undergone less than a total thyroidectomy
• Patients with aggressive histotype (poorly differentiated, tall-clear-cylindric cell, diffuse sclerosing, or with an anaplastic component)
• Patients having undergone total thyroidectomy less than 2 months or more than 5 months before inclusion
• Patients with cancer classified as pT1a unifocal (in which ablation is not necessary), or pT1N1, pT2, pT3, pT4 or N1 (who have a higher risk of recurrence) (classification TNM 2010)
• Patient with known distant metastasis
• Abnormal post-operative neck ultrasound of the lateral lymph node compartments
• Patients with another malignancy not in remission for at least 2 years (except for in situ cervix uterine cancer, basocellular skin cancer)
• Patients with a recent history of drugs affecting thyroid function, including injection of radiocontrast agents during the last 8 weeks.
• Patients previously treated with radioactive iodine or who previously underwent a whole body scan with radioactive iodine
• Pregnant or breast feeding women
• Subject with any kind of disorder that may compromise his/her ability to give written informed consent and/or to comply with study procedures