differentiated thyroid cancer: is there a need for radioiodine ablation in low risk patients?

Conditions: Low Risk Differentiated Thyroid Cancer

Summary: open-label randomized phase iii trial, using a non-inferiority comparison design. after randomization,patients will receive either post-operative radioiodine ablation with an activity of 1.1 gbq (30 mci) after stimulation by rhtsh, and then be followed-up (ablation group) or be followed-up (without postoperative radioiodine ablation) (follow-up group). the objective is to assess the non-inferiority of the proportion of patients without tumor-related event evaluated at three years after randomisation in the absence of radioiodine ablation (follow-up group) compared to the ablation group, in patients with low-risk differentiated thyroid cancer treated with total thyroidectomy with or without lymph node dissection (pt1am n0 or nx, pt1b n0 or nx)


Eligibility criteria:
inclusion criteria: 1. 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) 2. patients having undergone a total thyroidectomy with complete (r0) tumor resection, with or without lymph node neck dissection 3. total thyroidectomy performed 2 to 5 months before inclusion 4. 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). 5. 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 6. age \>=18 years 7. performance status of 0 or 1 8. patients who signed the informed consent 9. patients who can be followed-up annually during 5 years in order to assess the objectives of the study 10. women of childbearing age should have a negative pregnancy test before any radioiodine administration 11. both patients with or without thyroglobulin antibodies are eligible exclusion criteria: 1. patients having undergone less than a total thyroidectomy 2. patients with aggressive histotype (poorly differentiated, tall-clear-cylindric cell, diffuse sclerosing, or with an anaplastic component) 3. patients having undergone total thyroidectomy less than 2 months or more than 5 months before inclusion 4. 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) 5. patient with known distant metastasis 6. abnormal post-operative neck ultrasound of the lateral lymph node compartments 7. patients with another malignancy not in remission for at least 2 years (except for in situ cervix uterine cancer, basocellular skin cancer) 8. patients with a recent history of drugs affecting thyroid function, including injection of radiocontrast agents during the last 8 weeks. 9. patients previously treated with radioactive iodine or who previously underwent a whole body scan with radioactive iodine 10. pregnant or breast feeding women 11. subject with any kind of disorder that may compromise his/her ability to give written informed consent and/or to comply with study procedures