High-Dose Radioactive Iodine May Offer No Added Benefit in Intermediate-Risk Thyroid Cancer: Study
A retrospective study published in the Journal of the Endocrine Society evaluated 181 patients with intermediate-risk papillary thyroid cancer (PTC) treated between 2010 and 2022. Of these, 94 received moderate-activity radioactive iodine (RAI; 30–90 mCi), while 87 received high-activity RAI (more than 90 mCi). The findings suggest that routinely escalating to high-activity RAI after surgery may not provide additional benefits for many intermediate-risk patients. Treatment intensity should therefore be individualized according to patients’ risk profiles and clinical characteristics. The study was conducted by Mohammad J. and colleagues.
To make a comparison of the clinical results between the two different dosing regimens, a retrospective cohort study was performed among adult patients diagnosed with intermediate-risk PTC and undergoing treatment at a tertiary academic thyroid cancer center from 2010 to 2022. Patients were divided into two separate groups depending on the initial postoperative activity levels: moderate-activity RAI (30 to 90 mCi) and high-activity RAI (greater than 90 mCi).
The primary end point of the study was the time to recurrence. The secondary end point was the composite measure of persistent or recurrent disease at last follow-up. The IPTW statistical model was used in order to balance baseline confounders and selection bias between groups.
Key findings:
- Analysis among the 181 intermediate-risk PTC patients (median follow-up of 52 months) yielded equal clinical effectiveness of different dosages as well as specific clinicopathologic risk factors.
- Out of all 181 patients enrolled in the study, 94 were treated with moderate-activity RAI (30-90 mCi) and 87 patients were given high-activity RAI (>90 mCi).
- Among all the patients under analysis, 18 recurrences occurred at the end of the follow-up period (more precisely, 3 out of 94 for the moderate activity group vs. 15 of 87 for the high activity group).
- High-activity RAI did not yield better recurrence-free survival than moderate activity treatment (weighted hazard ratio [HR] 2.73; 95% CI 0.74 to 10.01).
- Disease recurrence and persistence affected 61 patients (34%) and no correlation was found in terms of the dosage group in the IPTW models (HR 0.97; 95% CI 0.53 to 1.76).
- According to the multivariate analysis, the extranodal extension, microscopic extrathyroidal extension, large lymph node deposit size and increased age were statistically correlated with disease persistence/recurrence.
The study concludes that 12-year retrospective data on observations prove that moderate-activity RAI (30 to 90 mCi) offers an equal amount of recurrence control compared to high-activity RAI in intermediate-risk papillary thyroid cancer. It should be noted that the findings of the research prove that high-activity RAI does not prolong recurrence-free survival of patients.
Reference:
Mohammad Jay, Iliana C Lega, Noemie Villemure-Poliquin, Cristina Goens, Afshan Zahedi, Moderate- versus high-activity radioactive iodine in intermediate-risk papillary thyroid cancer: a Canadian cohort study, Journal of the Endocrine Society, Volume 10, Issue 7, July 2026, bvag066, https://doi.org/10.1210/jendso/bvag066
