IoN
Is Ablative Radio-iodine Necessary for Low Risk Differentiated Thyroid Cancer Patients
Phase 3N = 504NCT01398085
- Population
- Complete (R0) resection after total thyroidectomy; pT1, pT2 or pT3 (TNM7) or pT3a (TNM8) disease; N0, Nx or N1a
- Design
- Multicentre randomised non-inferiority trial at 33 UK cancer centres: 1.1 GBq radioiodine ablation versus no ablation after total thyroidectomy (1:1, minimisation). Primary end point 5-year recurrence-free survival (absence of locoregional recurrent or persistent structural disease, distant metastases or death from thyroid cancer), non-inferiority margin 5 percentage points; per-protocol and ITT analyses. Patients had annual neck ultrasound and 6-monthly serum thyroglobulin. The abstract states the trial is still in active follow-up.
- Primary endpoint
- RFS
- Arms
- Radioiodine ablation (control, n = 253): 1.1 GBq radioiodine ablation after total thyroidectomy
- No ablation (experimental, n = 251): No postoperative radioiodine ablation
- People
- Mallick U
Δ 60-month RFS+1.6 pointsΔ 60-month RFS+1 points
Show the numbers
| Endpoint | Analysis | No ablation | Radioiodine ablation | Effect |
|---|---|---|---|---|
| RFSITT (504 randomised: 251 no ablation, 253 ablation)Absence of locoregional recurrent or persistent structural disease, distant metastases, or death from thyroid cancer. | primaryMallick 2025 | 97.9% at 5 y (96.1–99.7%) | 96.3% at 5 y (93.9–98.7%) | P=0.033The p-value is for non-inferiority (margin 5 percentage points). The 5-year absolute risk difference was 0.5 percentage points (95% CI -2.2 to 3.2). 17 recurrences occurred (8 with no ablation, 9 with ablation). Median follow-up 6.8 years (IQR 5.6 to 8.6) with no ablation and 6.6 years (4.8 to 8.5) with ablation. The published absolute risk difference (0.5 percentage points) does not equal the difference between the two rounded rates (1.6); both are recorded as published. |
| RFSPer-protocol population (249 no ablation, 231 ablation)Absence of locoregional recurrent or persistent structural disease, distant metastases, or death from thyroid cancer. | primaryMallick 2025 | 97.9% at 5 y (96.1–99.7%) | 96.9% at 5 y (94.7–99.1%) | Per-protocol analysis of the primary end point, reported alongside the ITT analysis. |
| Endpoint | Analysis | No ablation | Radioiodine ablation | Effect |
|---|---|---|---|---|
| RFSITT (504 randomised: 251 no ablation, 253 ablation)Absence of locoregional recurrent or persistent structural disease, distant metastases, or death from thyroid cancer. | primaryMallick 2025 | 97.9% at 5 y (96.1–99.7%) | 96.3% at 5 y (93.9–98.7%) | P=0.033The p-value is for non-inferiority (margin 5 percentage points). The 5-year absolute risk difference was 0.5 percentage points (95% CI -2.2 to 3.2). 17 recurrences occurred (8 with no ablation, 9 with ablation). Median follow-up 6.8 years (IQR 5.6 to 8.6) with no ablation and 6.6 years (4.8 to 8.5) with ablation. The published absolute risk difference (0.5 percentage points) does not equal the difference between the two rounded rates (1.6); both are recorded as published. |
| RFSPer-protocol population (249 no ablation, 231 ablation)Absence of locoregional recurrent or persistent structural disease, distant metastases, or death from thyroid cancer. | primaryMallick 2025 | 97.9% at 5 y (96.1–99.7%) | 96.9% at 5 y (94.7–99.1%) | Per-protocol analysis of the primary end point, reported alongside the ITT analysis. |