OnCo
trialsTrialPositive

ESTIMABL2

Proved that most people with small, low-risk thyroid cancers can skip radioactive iodine after surgery without any increase in recurrence.

Non-inferiority met at 3 years (event-free 95.6% vs 95.9%, NEJM 2022) and at 5 years (Lancet Diabetes & Endocrinology 2024). Together with IoN and HiLo, it removed radioiodine from routine low-risk care in ATA and ESMO guidance.

Setting
Low-risk differentiated thyroid cancer (pT1a-T1b N0/Nx) after total thyroidectomy: no radioiodine vs 1.1 GBq ablation
Phase
Phase 3
Sponsor
Gustave Roussy / French Endocrine Tumour Group
Registry
NCT01837745
Headline result
3-year event-free 95.6% vs 95.9% (non-inferior).
Reported
2022
Enrolled
776
Replication
IoN (UK, Lancet 2025) reached the same conclusion in a pooled analysis.

Outcomes

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In plain words
What these results mean for people, not percentages
776 people took part
Patients without events at 3 yearsprimaryother endpoint
  • 95.6 vs 95.9 out of 100 reached this endpoint at 3 years with No radioiodine compared with Radioiodine 1.1 GBq; 0.3 fewer per 100.
  • On this measure the first group did worse, not better.
  • This endpoint is not one of the standard survival or response measures; read it alongside the trial's primary result.
  • These results apply to the people the trial enrolled: Low-risk differentiated thyroid cancer (pT1a-T1b N0/Nx) after total thyroidectomy: no radioiodine vs 1.1 GBq ablation. People in a different situation may not see the same effect.

Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.

776 participants enrolled.

Patients without events at 3 yearsprimary
No radioiodine95.6 of 100
Radioiodine 1.1 GBq95.9 of 100
Source
EndpointArmnValueHR (95% CI)pSource
Patients without events at 3 yearsprimaryNo radioiodine—95.6%——link
Radioiodine 1.1 GBq—95.9%
Replication
IoN (UK, Lancet 2025) reached the same conclusion in a pooled analysis.

Connected

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Pages like this

not linked directly; found by shared links

cancers

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Thyroid cancer

technologies

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Radioiodine therapy and whole-body iodine scanning

drugs

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ApprovedRadiopharmaceutical (beta/gamma emitter, natural uptake)
Radioactive iodine (I-131) · Sodium iodide I-131

institutions

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Gustave Roussy

terms

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Low-risk differentiated thyroid cancer (ATA risk)