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
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.
In plain words
What these results mean for people, not percentages
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
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Patients without events at 3 yearsprimary | No radioiodine | — | 95.6% | — | — | link |
| Radioiodine 1.1 GBq | — | 95.9% |
Replication
IoN (UK, Lancet 2025) reached the same conclusion in a pooled analysis.