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Is radioiodine ablation with 1.1 GBq (30 mCi) 131I necessary in low-risk thyroid cancer patients? Results from a long-term follow-up prospective study

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In patients with low-risk differentiated thyroid cancer (DTC), remnant ablation with radioiodine (RA) after total thyroidectomy (TT) is controversial. No benefits have been demonstrated in terms of mortality or disease-free survival. Recent evidence found that RA did not improve mid-term outcomes.


To evaluate initial response to treatment and long-term follow-up status in low-risk DTC patients after TT vs. TT + RA with 131I 1.11 GBq (30 mCi).


Prospective multicenter non-randomized study; 174 low-risk DTC that underwent TT were recruited an divided in two groups according to RA (87 ablated and 87 non-ablated). Response to treatment was evaluated at 6–18 months after thyroidectomy and at the end of follow-up with measurements of thyroglobulin, and anti-thyroglobulin antibodies levels, and neck ultrasonography.


Baseline characteristics of both groups were similar. Ablated patients: median age 45.5 years, 84% females, 95.4% papillary thyroid carcinoma (PTC), mean tumor size 16 mm; non-ablated: median age 45 years, 88.5% females, 96.6% PTC, mean tumor size 14 mm. Response to initial treatment was similar between both groups, with < 2% of structural incomplete response. Final status was evaluated in 139 cases (median follow-up of 60 months). Among ablated patients, 82.8% had no evidence of disease (NED), 12% had an indeterminate response (IR) and 5% a biochemical incomplete response (BIR). Non-ablated patients had NED in 90%, IR in 8.7% and BIR in 1.2%. No statistical difference was found between groups (p = 0.29). No patient had evidence of structural disease at the end of follow-up.


Our findings support the recommendation against routine RA in low-risk DTC patients.

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We thank the members of the Thyroid Department of Sociedad Argentina de Endocrinología y Metabolismo:

Abalovich Marcos, Abelleira Erika, Alcaraz Graciela, Bielsky Laila, Brenta Gabriela, Cabezón Carmen, Calabrese M. Cristina, Castro Jozami Lorena, Delfino Laura, Deutsch Susana, Fassi Julieta, Frascaroli Genoveva, Gauna Alicia, Guerra Jorgelina, Jerkovich Fernando, Lowenstein Alicia, Martínez María Paz, Moldes Sofía, Negueruela M. del Carmen, Oneto Adriana, Orlandi Ana María, Parisi Carina, Reyes Adriana, Rosemblit Cynthia, Russo Picasso Fabiana, Saban Melina, Sala Mónica, Schiro Laura, Schnitman Marta, Sklate Rosana, Silva Croome M. del Carmen, Storani María Elena, Zund Santiago, Zunino Anabela.

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All authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by VI, IC, and AC. The first draft of the paper was written by VI, IC, and AC and all authors commented on previous versions of the paper. All authors read and approved the final manuscript.

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Correspondence to Fabián Pitoia.

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This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of each hospital.

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Ilera, V., Califano, I., Cavallo, A. et al. Is radioiodine ablation with 1.1 GBq (30 mCi) 131I necessary in low-risk thyroid cancer patients? Results from a long-term follow-up prospective study. Endocrine 80, 606–611 (2023).

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