Around 1 in 5 people diagnosed with cancer in the UK take part in a clinical trial.
A trial looking at intensity modulated radiotherapy (IMRT) for advanced thyroid cancer
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This trial looked at different doses of IMRT for locally advanced thyroid cancer. Locally advanced thyroid cancer means that the cancer has grown outside the thyroid gland into the:
- voice box
- food pipe
- nearby bones
- main blood vessels
Cancer Research UK supported this trial.
More about this trial
This trial started in 2002 and these results were published in 2018.
At the time this trial was done, radiotherapy was a possible treatment for locally advanced thyroid cancer. But radiotherapy has side effects such as dry mouth and difficulty swallowing. Some side effects can continue for many years after treatment.
In this trial, researchers looked at a new way of giving radiotherapy called intensity modulated radiotherapy, or IMRT for short. IMRT allows the radiotherapy beams to be shaped to the exact treatment area. For some cancers, such as thyroid cancer, doctors can also vary the strength (dose) of radiotherapy within the beam. This means that the treatment is very precise and there is less damage to the healthy tissue around the cancer.
Everyone who joined this trial had IMRT. Some people had a lower dose of treatment and some had a higher dose. The main aims of this trial were to find out:
- the side effects of IMRT as a treatment for people with locally advanced thyroid cancer
- how well the treatment works
Summary of results
The research team found that using a higher dose of IMRT is safe. They think that a higher dose of IMRT also works better for people with locally advanced thyroid cancer. But they need more studies to find out for sure.
Of these 45 people, 15 had a low dose of radiotherapy (DL1) and 30 had a high dose (DL2).
People who join the low dose of radiotherapy group (DL1) had 28 treatments (fractions) of radiotherapy. And people who had the high dose of radiotherapy (DL2) had 30 fractions of radiotherapy.
Doctors looked at the number of people who still had severe side effects after 12 months of treatment. They looked at the results of 12 people from the DL1 group. And the results of 24 people from the DL2 group. They found that:
- 1 person from the DL1 group had severe side effects after 12 months of treatment
- 2 people from the DL2 group had severe side effects after 12 months of treatment
A year after treatment, the researchers looked at the most common side effects in both groups. These included:
- difficulty swallowing
- narrowing of the food pipe
- difficulty breathing
- dry mouth
- scarring of the skin
- ear problems such as hearing loss and ringing in the ear (tinnitus)
- an uncomfortable sensation in the spine, legs and arms (Lhermitte’s syndrome)
How well the treatment worked
The trial team looked at how well the treatment worked. To do this, they looked at the number of people who were alive after 5 years of treatment. This is called overall survival.
Doctors found that:
- almost 7 out of every 10 people (almost 70%) who joined the DL1 group were alive 5 years after treatment
- more than 8 out of every 10 people (more than 80%) who joined the DL2 group were alive 5 years after treatment
The trial team concluded that a high dose of IMRT is safe to use. But doctors still have concerns about the severe side effects people have after treatment.
Doctors also think that the high dose of IMRT works better for people with locally advanced thyroid cancer. But this trial only looked at a small group of people. Doctors need more studies to find out for sure.
We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (
How to join a clinical trial
Professor Christopher Nutting
Cancer Research UK
The Royal Marsden NHS Foundation Trust