Thyroidectomy without radioiodine in patients with low-risk thyroid cancer: 5 years of follow-up of the prospective randomised ESTIMABL2 trial
Mené sur 776 patients ayant subi une thyroïdectomie totale avec ou sans curage prophylactique des ganglions lymphatiques du cou pour un cancer différencié de la thyroïde à faible risque de récidive (âge médian : 52,9 ans ; 82,7% de femmes), cet essai randomisé multicentrique de phase III évalue la non-infériorité, du point de vue de la proportion de patients sans événement, d'une stratégie de suivi sans administration d'iode radioactif (131I) par rapport à une administration postopératoire de 131I
Résumé en anglais
Background: ESTIMABL2, a multicentre randomised phase 3 trial in patients with low-risk differentiated thyroid cancer (ie, pT1am or pT1b, N0 [no evidence of regional nodal involvement] or Nx [involvement of regional lymph nodes that cannot be assessed in the absence of neck dissection]), showed the non-inferiority of a follow-up strategy without radioactive iodine (131I) administration compared with a postoperative 131I administration at 3 years post-randomisation. Here, we report a pre-specified analysis after 5 years of follow-up.
Methods: Patients treated with total thyroidectomy with or without prophylactic neck lymph node dissection, without postoperative suspicious findings on neck ultrasonography, were randomly assigned to the no-radioiodine group or to the radioiodine group (1·1 GBq-30 mCi after recombinant human thyrotropin-stimulating hormone). Follow-up consisted of annual thyroglobulin and thyroglobulin antibody determinations during levothyroxine treatment and neck ultrasonography in odd-numbered years. An event was defined as abnormal foci of 131I uptake on the post-treatment whole-body-scan requiring subsequent treatment, abnormal neck ultrasonography, elevated thyroglobulin levels, increasing titres or appearance of thyroglobulin antibody (using the same laboratory assay), or a combination of these definitions. Non-inferiority of the proportion of patients without an event in one group compared with the other at 5 years after randomisation was shown if this proportion and its CI did not differ by more than –5%. This study was registered on ClinicalTrials.gov (NCT01837745) and is completed.
Findings: Of the 776 patients (n=642 [82·7%] female and n=134 [17·3%] male, median age 52·9 years [IQR 42·6–63·1]) enrolled, 698 were evaluable at 5 years. The proportions of patients without events were 93·2% in the no-radioiodine group and 94·8% in the radioiodine group, for a difference of –1·6% (90% CI –4·5 to 1·4). Events consisted of structural or functional abnormalities (n=11) and biological abnormalities (n=31).
Interpretation: The non-inferiority of a follow-up strategy compared with postoperative 131I administration in low risk differentiated thyroid cancer was confirmed at 5 years. There is no loss of opportunity in following these patients without postoperative ablation.
