A trial looking at standard radiotherapy and intensity modulated radiotherapy for parotid gland cancer (COSTAR)

The trial team found that IMRT didn’t reduce the amount of hearing loss in people with parotid gland cancer.

Trial design
This phase 3 trial ran only in the UK. 110 people took part.

There were 2 treatment groups. People were put into a group at random:

• 54 had standard radiotherapy
• 56 had IMRT

Randomisation 1

Everyone had regular hearing tests. These measured hearing in both ears using a technique called audiometry. A specialist (audiologist) did the test:

• before radiotherapy 
• at 6 months
• at 1 year
• at 2 years 

Results
At 1 year the team had the full results for 67 out of 110 people. They don’t have all the results for everyone because:

• some people hadn’t gone to their check up appointments 
• some of the information from the hearing tests was incomplete

The team looked to see who had developed hearing loss. This means there is a problem in either the inner ear or the nerve, which delivers sound to the brain. 

They found this had happened in:

• 14 out of 36 people (39%) who had standard radiotherapy 
• 11 out of 31 people (36%) who had IMRT 

The team found no difference in hearing between the 2 groups at: 

• 6 months 
• 2 years

Damage to the inner ear can cause problems with balance. So the team checked this before starting radiotherapy and after it had finished. They didn’t find a difference between the 2 groups. 

The team also looked at the number of people whose cancer came back. At 2 years they found this was similar for both groups:

• 9 people (17%) who had standard radiotherapy
• 12 people (21%) who had IMRT

At 2 years they looked at the number of people living. This was also similar for both groups:

• 43 people (80%) who had had standard radiotherapy 
• 46 people (82%) who had IMRT

How people rated their hearing and quality of life 
The team asked everyone to rate their hearing based on activities such as listening to the tv or having conversations.

They also looked at how people rated their quality of life . 

They found there was no difference in either of these between the 2 groups.

Side effects
The team looked at the side effects of treatment. 

During radiotherapy and for up to 8 weeks afterwards they didn’t find a difference in side effects between the 2 groups.

They also looked at the long term side effects. People who had IMRT had more problems with a dry mouth. This was an unexpected side effect but it got better after a while. 

We have information about the side effects of radiotherapy to the head and neck. 

Conclusion
The research team concluded that IMRT didn’t reduce hearing loss. 

These weren’t the results that the team were expecting. They think it may be because the dose of radiation to the cochlear in the IMRT group was still too high. 

Even so, all trial results help doctors and researchers understand more about different cancers and the best way to treat them. 

Where this information comes from    
We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (peer reviewed ) and published in a medical journal. The figures we quote above were provided by the trial team who did the research. We have not analysed the data ourselves.