Treatment with cyberknife stereotactic radiotherapy
I have heard of a new cancer treatment called cyberknife. What is it, and which cancers can it treat?
To answer this question, there is information on this page about
Cyberknife is a machine for giving stereotactic radiotherapy or radiosurgery to cancers that doctors cannot remove with surgery. Cyberknife has been talked about a lot since it was featured in newspaper articles in the UK. It can be quite confusing because the names used for this type of treatment vary so much. The proper name is either stereotactic radiotherapy or radiosurgery. The Cyberknife and the Gamma Knife are brand names for types of machine.
Claims were made in the news in 2009 that Cyberknife is a life saving treatment for pancreatic cancer. But there is no clinical evidence to back up these claims.
So, the Cyberknife is a machine that delivers stereotactic radiotherapy. You can also have this type of treatment using other specifically designed machines, such as the Gamma Knife, or with a conventional radiotherapy machine (a linear accelerator) that has been slightly adapted.
Like standard external radiotherapy, stereotactic treatment delivers high doses of radiation. But it uses lots of radiation beams instead of just one. Each of the individual beams carries a very small amount of radiotherapy. Because all the beams meet at the tumour, the tumour receives the full dose. The doctors can aim very precisely at a tumour from a number of different angles. This allows them to give a high dose of radiation to the tumour, but a much lower dose to surrounding normal tissues.
You can also have this treatment in fewer individual treatment fractions. With stereotactic radiotherapy you have only a few treatments, or a single treatment. As the dose from each beam is quite low, and it is only the tumour that is getting the total dose, it is safer to do it this way than it would be with regular radiotherapy.
A single treatment is sometimes called radiosurgery. But the terms people use are very mixed up so you can't assume that radiosurgery always means only one treatment.
There is more information about stereotactic radiotherapy in general in our radiotherapy section. And about stereotactic radiation for brain tumours using the gamma knife in the brain tumour section.
All the stereotactic radiotherapy machines work slightly differently, so exactly how you have treatment will vary. With the Gamma Knife machine, you need a head frame to keep your head completely still during the treatment. The head frame is attached to your head under anaesthetic. There is detailed information about this type of treatment in the page about stereotactic radiotherapy for brain tumours.
The other machines don’t use a frame. They have built in imaging, or regular scan results are fed into the machine's computer. This allows doctors to target radiotherapy beams accurately at the tumour, even if the tumour moves as you breathe. The doctor checks that radiation is directed at the tumour, and not the surrounding healthy body tissues. Because of this, stereotactic radiotherapy can treat cancers in parts of the body that move, such as the lung or other body areas nearby.
As it is a new treatment, researchers are still looking into which cancers stereotactic radiotherapy can treat. Doctors have tried it for tumours that either can’t be removed with an operation, or have already been treated with radiotherapy.
It is important for new treatments to be compared with standard treatments in controlled trials so that we can be sure that a new treatment is better than an existing one.
Most of the published research on stereotactic radiotherapy is looking at tumours that have either started in the brain and spine, or spread there from another primary cancer. There is also some research looking at treatment of very early stage lung cancers, at primary liver cancer and cancer that has spread to the liver. So far, very little research has been done into any other type of cancer. Some early results from trials look promising, but it is too early to say how well it works for all types of cancer. We need more research to find out.
Generally speaking, stereotactic radiotherapy is used to treat quite small tumours. This is because it gives such high doses of radiation. A size limit of 3cm tumours is often mentioned in published research. But this is likely to change as research continues and may vary between types of cancer and their position in the body.
There is not a great deal of information available about the side effects of this treatment yet. Or much information about how well it works for different cancer types. We know from some research that it could increase side effects of treatment, such as ulceration or death of nearby normal tissue (doctors call this necrosis, or necrotic tissue). But generally speaking, this treatment hasn’t been in use long enough to know what the long term effects are yet.
There is a page on radiotherapy research in our main radiotherapy section.
There are specific Cyberknife treatment centres in the UK, including within the NHS. But remember that Cyberknife is a brand name for one type of machine that delivers stereotactic radiotherapy. So this treatment is available more widely than just at Cyberknife centres, including many NHS radiotherapy units. There are also Gamma Knife centres within the NHS, that mostly specialise in treating brain tumours.
If you think this treatment may be right for your type of cancer, you would need to get your own doctor to make a referral to one of the centres for you. You can't approach the hospitals to refer yourself.
But if you already have a radiotherapy specialist, do ask them about all this. It is quite possible that this type of treatment is already available at your centre, but not called 'Cyberknife'.
Some private clinics in London have Cyberknife treatment machines. They sometimes also treat NHS patients, but you would still need a referral from your own doctor.
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