Low-activity RAI as effective as high-activity RAI for thyroid cancer ablation: Study

Postoperative radioactive iodine (RAI) remnant ablation for differentiated thyroid cancer (DTC) facilitates the early detection of recurrence and represents an adjuvant therapy that targets persistent microscopic disease. The optimal activity of RAI in low- and intermediate-risk DTC remains controversial.

Hence, Danielle L. James and colleagues from the Department of Surgery, Galway University Hospitals, Galway, Ireland conducted the study to evaluate the long-term cure rate of different RAI activities in low- and intermediate-risk DTC. Secondary outcomes included successful remnant ablation, adverse effects, and hospital length of stay.

All RCTs or observational studies evaluating patients with low- and intermediate-risk DTC who were treated initially with total/near-total thyroidectomy, followed by remnant RAI ablation with either low or high activities. Eligible studies had to present odds ratio, relative risk (RR), or hazard ratio estimates (with 95% CIs), standard errors, or the number of events necessary to calculate these for the outcome of interest rate.

Dichotomous variables were pooled as risk ratios and continuous data as weighted-mean differences. Quality assessment of the included studies was performed using the Newcastle-Ottawa and Jadad scales. Disease recurrence was the primary outcome. Secondary outcomes included successful ablation, adverse effects, and length of stay.

The results showed that ten studies that included 3821 patients met inclusion criteria, including 6 RCTs and 4 observational studies and it was observed that there was no difference in long-term cure recurrence rates (RR, 0.88; 95% CI, 0.62-1.27, P = .50) or successful remnant ablation (RR, 0.95; 95% CI, 0.87-1.03; P = .20) between low-activity and high-activity RAI.

Hence, the authors concluded that "low-activity RAI was comparable with high-activity RAI regarding successful ablation and recurrence rates. This suggests that low-activity RAI is preferable to high-activity in low- and intermediate-risk DTC because of its similar efficacy but reduced morbidity."