# A preliminary study to evaluate efficacy and safety of Lugol’s solution following radioiodine for remnant ablation in differentiated thyroid cancer

## TL;DR

This study tested if adding Lugol’s solution after radioiodine therapy improves thyroid cancer treatment effectiveness and reduces long-term side effects.

## Contribution

The study is the first to show that Lugol’s solution may reduce long-term adverse events after radioiodine therapy in thyroid cancer patients.

## Key findings

- Lugol’s solution did not improve ablation success rates but showed a trend toward better outcomes with stricter criteria.
- The test group had significantly fewer long-term adverse events compared to the control group.
- Short-term adverse events were slightly higher in the test group but not statistically significant.

## Abstract

This randomized controlled trial aimed to determine if Lugol’s solution following radioactive iodine (RAI) therapy enhances the efficacy of ablation and mitigates radiation-induced toxicity in patients with differentiated thyroid cancer.

In this prospective study, 97 patients were enrolled and randomized to control group (RAI) and test group (RAI + Lugol’s solution). The primary endpoint was the rate of successful ablation. The secondary endpoint was short-term (d3 and d10) and long-term (6- to 9-month after RAI therapy) adverse events (AEs).

The rate of negative DxWBS was similar between control and test group (93.3% vs. 91.2%, p = 0.748). At the 6- to 9-month follow-up, while the successful ablation rate (sTg <1 ng/mL) was numerically higher in the test group compared to the controls (82.8% vs. 66.7%, p=0.131), applying a stricter stimulated thyroglobulin (sTg) cutoff (<0.2 ng/mL) revealed a statistically significant advantage for the test group (65.7% vs. 40.0%, p = 0.041). Uni- and multi-variate analysis showed Lugol’s Solution administration significantly correlated with lower level of sTg at the 6- to 9-month follow-up. The two groups exhibited comparable short-term AEs rates (46% vs. 34%, p = 0.230) and profiles. The most common AEs included neck swelling, pain, loss of appetite and dry mouth. However, the control group reported 2 cases of long-term AEs, whereas none were observed in the test cohort.

In this preliminary study, the addition of Lugol’s Solution following RAI showed non-inferior ablation efficacy with a numerically lower incidence of long-term AEs, despite numerically higher short-term AE rates.

It was registered at Chinese Clinical Trial Registry with identifier ChiCTR1900027705 at November 24th, 2019.