CyberKnife stereotactic ablative radiotherapy (SABR) and its side effects
CyberKnife treatment is a form of highly focused radiotherapy (see ‘Radiotherapy and chemoradiotherapy’) also known as stereotactic ablative radiotherapy or radiosurgery. Unlike conventional radiation therapy techniques traditionally used to treat pancreatic cancer, the CyberKnife machine delivers a high dose of radiation in a single or small number of treatments.
The CyberKnife robotic radiotherapy machine is mounted on a highly manoeuvrable base which is controlled by a state of the art guidance system. During the CyberKnife procedure, cameras monitor any patient movement, including breathing, so that the robot can reposition the beam in order to minimise damage to healthy tissue. The area liable to be damaged by this type of radiotherapy is smaller than that liable to be damaged by traditional radiotherapy, but because a high dose of radiotherapy is given in a relatively small number of treatments, the damage itself can be quite severe. For example, CyberKnife treatment can cause severe ulceration and bleeding, a serious complication, but to a small area of the bowel. CyberKnife treatment requires no anaesthesia and patients can usually be treated and go home on the same day.
A consultant explains that CyberKnife is focused radiotherapy, and that it has some potential...
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Cyberknife is really just focused radiotherapy and I think it’s important that, the concept of the name, it is not surgery, it is not removing the tumour in any way, it is no more effective in damaging the tumour than normal radiotherapy but the principle advantage of stereotactic or targeted radiotherapy is that a dose can be, a given dose can be administered more quickly so you’ll get a dose in two to three days that would otherwise take three to four weeks.
And the effect on other organs around the target area may be reduced slightly. So there is a potential advantage of focused radiotherapy in terms of reducing the side effects that you might get from the standard radiotherapy but in terms of actually being more effective in damaging the tumour, it is not going to make any miraculous change to the effect of radiotherapy, standard radiotherapy alone.
Although there are potential advantages in using this treatment, most of the published research has been done observing what has happened to people treated with it, rather than comparing it with standard treatments. Without controlled clinical trials it isn’t possible to tell whether a new treatment is any better than an existing one (see ‘Clinical trials’). Because there has been very little testing, doctors know less than they’d like about the side effects of this treatment or how well it works for people with pancreatic cancer. The National Institute of Health and Clinical Excellence (NICE), which advises the NHS on which treatments represent value for money, is assessing the potential benefits of CyberKnife. CyberKnife machines are currently only available in a few NHS hospitals and private clinics and may not be available outside of a clinical trial.
Two men we interviewed had had CyberKnife treatment at a private clinic in London. Michael had had a Whipple’s operation followed by chemoradiotherapy, but in March 2010 he had a recurrence. He was delighted when a multidisciplinary team at a private clinic decided that he was suitable for CyberKnife treatment. Another man, Peter (Interview 43), had inoperable pancreatic cancer. He had some chemotherapy and then heard about CyberKnife treatment. He asked his consultant to refer him to a doctor in a private clinic that provided this treatment.
Michael explained why the doctors decided that CyberKnife treatment was suitable for him. His...
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Yes, and therefore it [the tumour] was isolated. And as such my oncologist felt that I would be eligible for this literally state of the art, brand new treatment called Cyberknife. He therefore wrote a letter to my radio, radiotherapy consultant and both of them put up the case to the Cyberknife team, which is a multidisciplinary team, and unless your sort of diagnosis fits their model it is very difficult, you are not able to have Cyberknife and one of the criteria is if its, if it’s a very large tumour you can’t have it, or indeed if it’s spread, if it’s metastasized, again you can’t have it so in that way I was extremely lucky that mine was isolated and therefore they felt that it was ideal for Cyberknife.
Anyway their proposal went forward to the Cyberknife multidisciplinary committee and to my great good fortune they agreed that it, that I was a suitable patient to have the treatment. But the only downside was that the treatment is actually extremely expensive and in fact costs I would say about 25,000 [pounds] for three, between three and five sort of shots. And this, that would include the placement of a fiducial which I will talk about in a minute. And therefore clearly for, this might be out of, beyond the reach of some people, and indeed many people. I was very lucky in that my life insurance company, sorry my health insurance company having initially said that the treatment was too new and there was no compelling evidence to say that it worked, and therefore they doubted that they could help me, reviewed the case and in fact did agree to help me so my treatment was covered which was incredibly fortunate actually.
Before CyberKnife treatment starts people have CT scans. They may also have an MRI scan or Positron Emission Tomography (PET) scan (see ‘Other diagnostic investigations’). A PET scan can show how body tissues are working, as well as what they look like. The doctor puts information from the scans into the CyberKnife machine’s computer. By mapping a tumour three dimensionally before treatment, doctors can calculate the dose of radiation to match the shape, density and position of a tumour. The tumour is then ‘marked’ with tiny particles of gold to define the position of the tumour with millimetre precision. The marker is called a fiducial.
Peter had a PET scan so that doctors could make sure he was suitable for CyberKnife. The next...
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You’d heard about Cyberknife?
I’d heard about Cyberknife and I asked the hospital to put me, investigate and put me in touch. So I ended up going down to London to see a specialist. It was a fool’s errand because they [the hospital consultant] had not supplied the specialist with any information. So he hadn’t a clue what was going on or anything. So the trip to London was a complete and utter waste of time.
Was that a specialist who knew about Cyberknife?
He’s the pioneer; he’s the one who’s introduced it to this country.
So you had to go back for more information?
So I went back again, and he said, “Well you look to me an appropriate case for Cyberknife treatment.” And he told me of course that it could only be done privately. But I said, “Well I’m covered for medical insurance. I don’t see that as a problem.” And he said, “Before we go any further you’ll need a PET scan to make sure there are no problems anywhere else in your body because if there are I can’t do anything for you.”
Anyway the PET scan which was held at the local hospital, and probably the first on a newly installed machine proved highly satisfactory. So with this information which had been sent on to the specialist, I was accepted for Cyberknife treatment and that started in basically May 2009 when there was a couple of consultations then blood tests, then the scan and then the most important bit, or one of the most important, was the planting of gold seeds on the tumour so that the laser could pinpoint exactly where to go.
How did they do that?
Oh they stuck needles [noise]
It was a local anaesthetic?
Yes, probably. It was a lengthy procedure. I went in early in the morning, so let’s say 10 o’clock; they put me in a bed. And after the, what they called the placement of the seeds, I had to go back to bed for three or four hours before I was allowed out. The doctor, specialist, by this time had seen a scan of the procedure and said, “It’s worked, you’re okay, the gold seeds are in place so we shall now go ahead with the Cyberknife itself.”
Michael described what happened when his tumour was marked with tiny particles of gold (fiducials...
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Right so after that, as I say, I was identified as a suitable patient. And the next step was to have something called a fiducial, which is where they implant gold seeds into the centre of the tumour, which acts as a marker for the Cyberknife rays. And what happens here, you go to hospital and they give you a local anaesthetic in the affected area, and then inject, in my case through my tummy into the particular, into the area, of the pancreatic area where the tumour was, a long needle which he showed me, it was about 12” long, it was a bit frightening [laughs].
Then they inject these gold seed into the centre of the tumour and they do it by using a CT scanner and they can be incredibly accurate. I must say that the, the chappie who did it for me was I think absolutely brilliant, it was, when I think what he had to do and you know, making certain the needle didn’t pierce any of the arteries and all of the veins and this sort of thing, I think he was completely brilliant actually, and a lovely manner as well which is very important because it is quite frightening when you see this massive great needle being thrust into you. But he was very good, he had the CT scan and he guides it into the centre of the tumour via the CT scan.
How did you feel?
In my particular case and as, what he, as the needle goes in there’s another needle beside it, which in fact injects anaesthetic as you go down and so the area is numb. For me it was, I must say relatively painless. There were two or three, only one what I would call major twinge, but generally speaking I was amazed at how painless it was. I know some people have suffered and felt more and it has been a lot more painful, but certainly as I say in my case I was very lucky.
People return to the clinic on another day for the treatment itself. The patient lies inside a plastic mould made to the shape of their body to restrict their movement. This is placed on a movable treatment table and the robotic arm moves around them. During treatment they have to lie very still. The treatment does not hurt. Patients usually have one to five treatment sessions, which can be on consecutive days. Each session generally lasts from 30 to 90 minutes depending on the dosage and the complexity of the tumour, and the treatment duration is considerably more than standard chemoradiotherapy.
During the CyberKnife treatment Michael had to lie very still for an hour. He liked the...
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So my area, my treatment was mapped out and I duly turned up at the Cyberknife centre, and I must say here that the team were absolutely amazing throughout, really sensitive, very warm, and highly professional. And it consisted basically of two operatives, and then a doctor who was there who would see you every time to see how you reacted to the treatment, what you felt and whether you need, what extra medication you needed.
And then the actual consultants themselves were not present because the guy doing it said, “They’re not actually allowed to operate the machines. These have to be done by the operatives themselves.”
So the other thing, beforehand when you have the CT scan, I’ve got, they make this mould for your body because you have to lie down and between 30 minutes and one hour and twenty minutes, absolutely still. So they, they make this mould so you’re, not quite like in a, in a coffin, that’s a rather bad analogy, but you have to remain absolutely still. And then you have a rest for your ankles and then also for your, a head rest.
So how long do you have to lie in it did you say?
R' Between thirty, thirty minutes and one hour twenty. I actually had to lie in it for an hour…
So as I say I arrived at the centre and you slip into this gown, and then they start, they start the treatment. And in my particular case you don’t, you don’t actually feel anything during the time, you can’t see anything, and all you can, all you can see is this robotic arm moving around you at 180 degrees and going into 151 different positions. And in my particular case, they, the machine automatically changed its, its sort of head to a one to give a finer beam or a thicker beam as it needed…
And they had music, it, it’s a very, extremely modern set up so you don’t get this sort of old hospital atmosphere. So it’s a good atmosphere to have it in. And one thing before you start you see the nurse and they explain everything that’s going to happen, and explain that they’ll give you these nausea drugs and anything else that you particularly need.
Peter described what CyberKnife treatment was like. It was painless and he listened to music that...
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And then you went back to have the Cyberknife Treatment. Can you say what it was like to have the treatment?
It, there was no problem, no pain; no anaesthetic was needed. You just lay there while this machine whirled around, pointing downwards, sideways, every possible angle, booming laser guided radiotherapy at the tumour. And all you had, all I had to do was not move and to facilitate this they’d got a plastic sort of moulded, a bit like an Egyptian Mummy’s coffin. You lay in it and you can’t move very much [laughs]. And your arms are straight down by your side. They, they were good enough to play, let you listen to a musical tape of your choice, and I chose classical music. And I think at one stage I drifted away into a nice little sleep.
How long did you have to lie still for?
An hour and a half. We mentioned that earlier on. Yes an hour and, it was, well an hour and a quarter to an hour and a half each time. And then it was just get up and go.
And that was three days?
Three days, June 1st, June 2nd, June 3rd.
The side effects of CyberKnife treatment are similar to the side effects people experience after standard radiotherapy. Although the treatment is convenient as it is given over a small number of treatments (1-5 treatments, compared to 25-30 treatments for standard radiotherapy) but the risk of bleeding and bowel ulceration is higher than standard radiotherapy or chemoradiotherapy. (see ‘Side effects of radiotherapy and chemoradiotherapy’). Michael had some quite bad side effects but Peter had none.
After CyberKnife Michael had indigestion, nausea and felt exhausted. He found it hard to sleep...
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Were you actually being sick, or just felt sick?
No I was, I was never actually sick, but it was that sort of bilious feeling in one’s stomach which is really debilitating and the worst side of it was because of this and the indigestion, I couldn’t sleep. And of course you know you then got tireder and tireder, and more debilitated and everything appeared to be rather black at that stage. So once I started managing to get some sleep things, the situation much improved.
So you actually felt very uncomfortable?
Yes, yes well I didn’t feel, it wasn’t, I didn’t feel much pain as a result of this, it was this indigestion which was, I think actually a build up of wind, and I’m sure it was, a build up of wind in, in below one’s sort of rib cage, and round to the, to various parts in one’s tummy. And that combined with the nausea was very, very uncomfortable actually.
Could you eat anything?
I did eat, but my appetite obviously wasn’t brilliant so I lost more weight, but now I suppose, my treatment ended on 26th May so it’s what, July, nearly 7 weeks now, I suppose after the treatment and I am feeling much better now. And I’m trying to put on more weight. I do find I get tired.
I’m actually talking to; I did go and ask, there was a very good symptoms manager, and also a sort of psychiatrist who’s attached to this particular unit. And I did have some word with them, counselling, because I wanted to try and tackle this from two areas, a) the physical side but b) the sort of psychological side. And he said I think it was very appropriate word, he said, “Well the word convalesce has actually dropped out of the English dictionary now, and people they finish their treatment and immediately feel they can sort of get on with their daily lives,” And he said, “After your treatment where effectively you’ve had six weeks radiotherapy in three days, you know, your body really has taken a hammering, and if you think what sort of hammering it’s taken over the last three years it has been pretty substantial. And so you really must take care of your fatigue and pace yourself accordingly.” And he said, “The difference between fatigue and tiredness is that tiredness you wake up refreshed when you fall asleep, and fatigue you wake up feeling exhausted.”
And you’re still feeling a bit like that?
I still feel a bit like that. The trouble is if you have a fairly sort of full on life here and it is, it needs a conscious effort to sort of slow down and, but I, I really think it is important because if this fatigue starts getting the better of you, you then get depressed and you know, emotional and life looks a bit, looks rather black.
And they did say actually one of the, one of the side effects of this Cyberknife is that you, you can get very emotional, so that is, I think people need to be aware of that. I’m not, and certainly their partners or people looking after them need not to be worried that they, it is just the side effects of it which will disappear as time goes on.
Did they mention any other side effects?
The other side effects so they said were, were basically, nausea, nausea, fatigue and I think those were basically, basically it. Obviously different people behave in different ways and in my particular case I had the added one of indigestion.
Does it affect the skin at all?
Ah, yes, and they said that if you had been irradiated before it could affect the skin, in my particular case it, it didn’t.
Last reviewed September 2018.
Last updated September 2018.
Last updated September 2018.