More time with loved ones for cancer patients spared radiation treatment

For many patients, radioactive iodine treatment after thyroid cancer surgery means side effects like nausea and time in hospital isolated from loved ones. But new clinical trial results from researchers at UCL mean hundreds of thousands of patients worldwide could now safely be spared this treatment.

Globally, around 820,000 people are diagnosed with thyroid cancer each year. Compared to most cancers, it affects a high proportion of younger people who are more likely to be parents to young children. It is also three times more common in women than men.

The Iodine or Not (IoN) clinical trial, funded by Cancer Research UK and published in The Lancet, sought to determine whether patients with low-risk thyroid cancer could safely forego radioactive iodine treatment following surgery to remove the thyroid, a butterfly-shaped gland in the neck that produces hormones to help regulate metabolism and energy levels.

The trial involved 504 patients aged 17-80 (with 153 aged 40 years or below) from 33 UK cancer centres, whose chances of their thyroid cancer returning were determined to be low. Half were randomly assigned to receive radioactive iodine treatment, which is designed to destroy any remaining cancer cells following surgery. The other half received surgery only.

The patients were assessed regularly for at least five years. By the end of the study, 98% of patients who did not have radioactive iodine were still free from thyroid cancer, compared to 96% who did receive it (though the latter number is lower, the authors say that this is likely down to chance rather than any clinically significant factor).

Professor Allan Hackshaw, an investigator of the trial from UCL Cancer Institute, said: “Our results show that radioactive iodine represents over-treatment in these particular patients and is not required to improve their outcomes. The only impact of not receiving this radiotherapy was a positive one on people’s quality of life.

“This is particularly important because around a third of patients in the study were aged 40 years or less, and many would have children to care for. Not having physical contact can be quite hard for them. Being spared radioactive iodine therapy means they will be able to get back to a near normal life much more quickly, as well as receiving the emotional and physical support of their families in the weeks after their operation.”

The authors estimate that 2,500 patients in the UK and 400,000 patients worldwide could potentially avoid radioactive iodine treatment each year.

Currently, radioactive iodine is considered for most patients following surgical removal of the thyroid gland for cancer. Patients are given this treatment in hospital and must be isolated in a radiation-protected room to avoid contact with people for between one and three days.

Patients are also asked to follow safety precautions for several more days after leaving hospital. This involves avoiding or minimising contact with other people to protect them from any radiation exposure, particularly physical contact with children who are more susceptible to the low level of radioactivity the patient may have.

Dr Ujjal Mallick, an expert oncologist from the Freeman Hospital, Newcastle, who was the trial’s chief investigator, said: “This study represents a major improvement in how thousands of thyroid cancer patients might be treated worldwide. They can avoid the risk of side effects of radioactive iodine treatment such as changes in taste, salivary gland problems, dry mouth, changes in taste, lacrimal gland problems and also the very small risk of a new and different cancer in the future.”

As well as the benefits for patients, foregoing radioactive iodine treatment would mean lower healthcare costs, reducing the pressure on clinical staff and hospital beds. The investigators say that there is no reason why the improved treatment regimen cannot be incorporated into clinical guidelines immediately, in the UK and globally.

Dr Kate Newbold, Consultant Clinical Oncologist at The Royal Marsden NHS Foundation Trust and co-investigator of the study, said: “IoN is an exemplar study that shows that the UK can successfully run major practice-changing clinical trials in cancer – with impacts for patients and healthcare systems internationally.”

Kate Farnell, CEO of Butterfly Thyroid Cancer Trust, said: “On behalf of thyroid cancer patients we are delighted. Many tell us that having radiation treatment in isolation away from their family is perhaps the hardest part of their cancer journey. This trial has shown that in many patients this will no longer be necessary.”

The IoN clinical trial was developed by expert UK oncologists, clinical trial specialists and Butterfly Thyroid Cancer Trust, involving over 30 NHS centres. The trial was conducted by the Cancer Research UK & University College London Cancer Trials Centre, and funded by Cancer Research UK.

Notes to Editors:

For more information, please contact:

 Dr Matt Midgley

+44 (0)20 7679 9064

m.midgley@ucl.ac.uk

Publication:

Ujjal Malick et al. ‘Thyroidectomy with or without post-operative radioiodine for low risk differentiated thyroid cancer patients: a UK randomised multicentre noninferiority trial (IoN)’ is published in The Lancet and is strictly embargoed until Wednesday 18 June 2025 at 23:30 BST / 18:30 ET.

DOI: https://doi.org/10.1016/S0140-6736(25)00629-4

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