New Study Suggests Low-Risk Thyroid Cancer Patients Can Skip Iodine Treatment

A groundbreaking clinical trial from University College London (UCL) suggests that low-risk thyroid cancer patients may safely forgo postoperative radioactive iodine treatment, a decision that could significantly enhance their quality of life. Published on June 19, 2025, in The Lancet, the study opens new avenues in the management of thyroid cancer, potentially allowing thousands of patients to avoid the side effects and isolation typically associated with this treatment.

Globally, approximately 820,000 individuals are diagnosed with thyroid cancer annually, with a notably higher prevalence among younger individuals, particularly women, who are three times more likely to develop this condition. The Iodine or Not (IoN) trial assessed the necessity of radioactive iodine treatment for patients whose cancer recurrence risk was deemed low. The trial involved 504 participants aged between 17 and 80, drawn from 33 cancer centers across the UK. Half of the participants received radioactive iodine in addition to thyroid surgery, while the other half underwent surgery alone.

Over the course of the study, which monitored patients for a minimum of five years, results indicated that 98% of patients who did not receive radioactive iodine remained cancer-free, compared to 96% of those who did. Professor Allan Hackshaw from the UCL Cancer Institute, who was involved in the trial, emphasized that these findings indicate that radioactive iodine may constitute overtreatment for this patient demographic, asserting, "The only impact of not receiving this radiotherapy was a positive one on people's quality of life."

Dr. Ujjal Mallick, the trial's chief investigator and an oncologist at Freeman Hospital in Newcastle, noted that the study represents a significant shift in the treatment paradigm for thyroid cancer patients. He remarked, "This study represents a major improvement in how thousands of thyroid cancer patients might be treated worldwide," highlighting the side effects associated with radioactive iodine, including changes in taste and salivary gland issues.

The implications of this research extend beyond patient well-being; avoiding radioactive iodine treatment could alleviate healthcare costs and reduce pressure on hospital resources. Dr. Kate Newbold, a consultant clinical oncologist at The Royal Marsden NHS Foundation Trust and co-investigator, pointed out that the IoN trial exemplifies the UK’s capacity to conduct impactful clinical research that benefits both patients and healthcare systems globally.

Kate Farnell, CEO of Butterfly Thyroid Cancer Trust, expressed optimism regarding the trial's outcomes, noting, "Many thyroid cancer patients report that undergoing radiation treatment in isolation is among the most challenging aspects of their cancer journey. This trial has shown that many patients will no longer need to endure this experience."

As the medical community considers adjusting clinical guidelines based on these findings, the potential for improved patient care and reduced healthcare costs represents a promising future for thyroid cancer treatment. The authors of the study advocate for immediate incorporation of these findings into clinical practice, both in the UK and worldwide.

This significant trial not only highlights the evolving landscape of thyroid cancer treatment but also underscores the necessity of continued research and adaptation of clinical guidelines to reflect the latest scientific evidence. With the potential to spare over 400,000 patients globally from unnecessary treatment each year, the IoN trial marks a pivotal moment in the fight against thyroid cancer.