BACKGROUND
Thyroid cancer is common and usually has an excellent prognosis. This is largely because we have very effective treatments. Surgery is the usually first option. Historically, surgery was usually a total thyroidectomy to remove the entire thyroid and was often followed by radioactive iodine therapy to destroy all remaining thyroid cancer cells. More recently, a less aggressive approach is recommended, especially with small thyroid cancers with low-risk features. Radioactive iodine therapy is not an option with a lobectomy (removing 1 lobe of the thyroid, leaving the other lobe intact). Even in patients that undergo a total thyroidectomy, radioactive iodine is used less often and is reserved for patients with higher risk thyroid cancers.

Radioactive iodine therapy does cause side effects. It may damage the salivary glands, causing permanent dry mouth (xerostomia), and radiation may raise the risk of developing other cancers later in life. Thus, limiting its use to only patients that would benefit is important. Studies have suggested that patients with low-risk thyroid cancer do not benefit from radioactive iodine therapy. Indeed, the American Thyroid Association now recommends against using radioactive iodine therapy in low-risk patients. Still, there hasn’t been enough long-term data proving that skipping radioactive iodine therapy is safe.

This study was done to examine the long-term results of omitting radioactive iodine therapy in treating patients with low-risk thyroid cancer.

THE FULL ARTICLE TITLE
Leboulleux S et al. Thyroidectomy without radioiodine in patients with low-risk thyroid cancer: 5 years of follow-up of the prospective randomised ESTIMABL2 trial. Lancet Diabetes Endocrinol,. 2025;13(1):38-46; doi: 10.1016/ S2213-8587(24)00276-6.

SUMMARY OF THE STUDY
This was a trial of 730 patients aged 18 to 75 with low-risk thyroid cancer. “Low-risk” meant the cancer was smaller than 2 cm, showed no aggressive features, and hadn’t spread to the lymph nodes or other parts of the body. Participants were randomly assigned to one of two groups: one group had only a total thyroidectomy, and the other group had the same surgery followed by a low dose of radioactive iodine therapy. Researchers compared how many patients in each group were cancer-free after 5 years—called disease-free survival. They also looked at side effects and patient’s overall quality of life.

After 5 years, 698 patients remained in the study and 93.2% of the surgery-only group were cancer-free and 94.8% of the surgery-plus-radioactive iodine therapy group were cancer-free. This small difference was not statistically significant. Recurrence rates were very low and nearly the same — 6 in the surgery-only group vs. 5 in the radioactive iodine therapy group. No one in either group developed distant cancer, and overall survival rates were the same. However, those who did not receive radioactive iodine therapy reported better quality of life, with fewer issues like fatigue, and salivary gland problems.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This study provides strong evidence that surgery alone is enough for patients with low-risk thyroid cancer. Adding radioactive iodine therapy doesn’t improve outcomes and can lower quality of life. These findings support the growing trend to reduce aggressive treatment in low-risk thyroid cancer, because in some cases, the treatment may do more harm than good.

— Phillip Segal, MD

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