Patients with low-Risk Thyroid Cancer don't benefit with RadioIodine
After thyroidectomy, radioiodine (iodine-131) is generally administered both to ablate residual normal thyroid tissue and to treat persistent disease. However, in a recent study, researchers found that follow-up without the use of radioiodine after thyroidectomy was non-inferior to the administration of 1.1 GBq of radioiodine after the administration of recombinant human thyrotropin. The study findings were published in The New England Journal of Medicine on March 10, 2022.
There is a consensus to avoid radioiodine administration in patients with a unifocal microcarcinoma (≤10 mm in diameter), but the benefits of radioiodine administration in other patients with low-risk thyroid cancer remain controversial. Therefore, Dr Sophie Leboulleux and her team conducted a study to assess whether no radioiodine therapy was non-inferior to radioiodine therapy with respect to the absence of a composite endpoint that included functional, structural, and biologic abnormalities at 3 years.
In this prospective, randomized, phase 3 Essai Stimulation Ablation 2 (ESTIMABL2) trial, the researchers assigned patients with low-risk differentiated thyroid cancer who were undergoing thyroidectomy to receive ablation with postoperative administration of radioiodine (1.1 GBq) after injections of recombinant human thyrotropin (radioiodine group; n = 363) or to receive no postoperative radioiodine (no-radioiodine group; n = 367). They determined noninferiority as a between-group difference of less than 5 percentage points in the percentage of patients who did not have events. They also assessed the prognostic factors for events and molecular characterization.
Key findings of the study:
- After 3 years of follow-up, the researchers found that the percentage of patients without an event was 95.6% in the no-radioiodine group and 95.9% in the radioiodine group with a difference of −0.3 percentage points, a result that met the noninferiority criteria.
- They reported structural or functional abnormalities in 8 patients and biologic abnormalities in 23 patients with 25 events.
- They noted that the events were more frequent in patients with a postoperative serum thyroglobulin level of more than 1 ng per millilitre during thyroid hormone treatment.
- They also noted that the molecular alterations were similar in patients with or without an event and reported no treatment-related adverse events.
The authors concluded, "In patients with low-risk thyroid cancer undergoing thyroidectomy, a follow-up strategy that did not involve the use of radioiodine was non-inferior to an ablation strategy with radioiodine regarding the occurrence of functional, structural, and biologic events at 3 years".
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Keywords: low-risk thyroid cancer, thyroidectomy, follow-up strategy, radioiodine, thyroid disorder, ESTIMABL2 trial, unifocal microcarcinoma, noninferiority study, New England Journal of Medicine
