Cochlear sparing via intensity modulated radiotherapy
Dr Chris Nutting - Royal Marsden Hospital, London, UK
I’m at Chicago at ASCO to present the first results of a randomised controlled trial called COSTAR.
Could you tell us more about that trial and the results that you found?
COSTAR is a trial which was designed to investigate whether or not IMRT could reduce hearing loss in patients who are having radiotherapy to tumours of the head and neck region. We randomised 101 patients to the test arm which was cochlear sparing radiotherapy versus conventional radiotherapy and we unfortunately found that the IMRT didn’t make any difference to the degree of hearing loss which was about 40% in both treatment arms. So the study was negative.
Just to check, how were the arms randomised there? Was there any special selection?
It was a one to one randomisation of patients who had had surgery for parotid cancer and needed radiotherapy afterwards. They were stratified by the treatment centre in the UK, we had 22 centres participating, by the radiation dose they were to receive.
With these results in mind, based on the sample size is that something that you think should be followed up from different angles to see if there are other associated causes that could be limiting the hearing loss or something that should just be taken as hearing is not the problem and to move forward from that?
I think the radiation oncology community we were very surprised about the results today because we’d all assumed that reducing the radiation dose to the components of the ear would make a difference to people’s hearing. But what we’ve learned probably is that the radiation dose that we reduced to probably isn’t low enough and probably to spare hearing we need to go further.
Will that be something that you will be following up on?
Yes, there will be some follow up studies of this looking at patients, the cochlear doses and seeing if we can get even lower than we had attempted to do before. There was one unexpected side effect which was that the IMRT treatment, because it spreads some of the radiation dose around a bit more, led to some increased dry mouth in patients who had received the experimental arm. So not only did it not work but actually there was some evidence that it was detrimental as well.