THE SPECIALIST
Dr Alison Tree is a consultant oncologist at the Royal Marsden Hospital in Sutton.
The new radiotherapy machine we are trialling — called MR Linac — is a complete game-changer. If trials are successful, it could one day mean patients need only one session of radiotherapy, and could suffer no adverse effects.
Radiotherapy, where we use high-energy X-ray beams to shrink tumours, is extremely effective. But targeting the beams so they hit only cancerous tissue can be difficult, and healthy tissue may be damaged, leaving many patients with side-effects — in prostate cancer, for instance, this can lead to bowel and bladder problems and erectile dysfunction.
New and improved: The new technique being tested would save far more healthy tissue
These can be temporary, but about one in 20 men having radiotherapy is left with long-term damage to the rectum.
Until now, we’ve needed to add a 1cm to 1.5cm margin of error around the tumour at which we were directing the radiation, to ensure we got the cancer — and while this has been reduced over the years, often to just a few millimetres, it means we can still accidentally damage healthy tissue.
The new technique overcomes this risk because it does two things: it effectively combines an MRI scanner with a radiotherapy machine and scans the patient in real-time — the patient has the treatment inside an MRI chamber — to locate the cancer accurately, while simultaneously administering radiation.
This is something we have never been able to do before. It’s like levelling up on a computer game.
With traditional radiotherapy, a patient such as Barry would have had a CT scan to locate the tumour, then markers — three tiny gold pellets — would have been inserted into the prostate: these show up on X-rays during radiotherapy so we know roughly where to aim the radiation.
Being able to watch the cancer on a screen in real-time is significant because a patient’s anatomy is not the same each day, and the tumour can move. For example, breathing or a bowel or bladder movement can alter the position of prostate cancer even during a radiotherapy session.
Team: Physicist Adam Mitchell, Dr Alison Tree, Consultant Clinical Oncologist at The Royal Marsden, and Trina Herbert, MR Linac Lead Radiographer, monitor the treatment of Barry
Usually we treat a larger area than where the tumour is to account for this potential movement. But we can easily miss the tumour and damage healthy tissue.
With the new technique, the real-time MRI will pick up any movements and the radiation can be adjusted accordingly there and then, so it hits only cancer cells. Treatment can even be paused to adjust to any changes spotted on the scan on the screen.
It takes a bit longer than standard radiotherapy — a session lasts 45 minutes, compared with the usual ten to 20 minutes (generally patients need 20 sessions of radiotherapy) — but it is worth it due to the significantly lower risk of adverse effects.
For the patient, the radiotherapy session is quite similar. But instead of lying on a bed with a radiation machine over the target area, as with the traditional treatment, they are put inside an MRI chamber. We then administer radiation while they are in the chamber.
Barry underwent radiotherapy to treat his prostate cancer last month and was the first of the 30 patients in our trial, which is being overseen by the Royal Marsden Hospital and the Institute of Cancer Research.
Ours is only the third centre in the world to treat patients with this form of radiotherapy (the other two are in the Netherlands), although it will be available at The Christie in Manchester next year.
Last week, I was at a conference in Toronto, Canada, where the seven founding members of an international consortium that has been working on the MR Linac met to talk about our latest findings. Knowing we had treated Barry, our first patient, only days before, made it exciting and was the culmination of more than four years of working on this project.
It is thrilling to see the treatment in action, but we need to finish the trial before we can say it is superior to traditional radiotherapy.
Using what we learn from the prostate trial, we will then test the technique in rectal, bladder and gynaecological cancers — and then move on to pancreatic and lung tumours, which are more complex to treat.
It is my dream that one day a patient will only need one session of radiotherapy. If our method is proven to be safer than traditional radiotherapy, we’ll be able to give the full dose of radiation in one go, without fearing side-effects.
We’d be able to tell a patient they have cancer and that we can cure it with radiation in a single day.
It is a long way off, but it’s what we’re working towards — and this is a step in that direction.
THE PATIENT
One of my biggest reservations about radiotherapy was the risk of side-effects, which I was told might include severe discomfort, diarrhoea and erectile dysfunction.
But the new technique helps to avoid these, so it seemed like a no-brainer when I was asked if I’d like to join the trial. I was referred to the Royal Marsden Hospital in March after tests showed I had prostate cancer; I originally went to see the GP as I had noticed I was going to the loo more often than normal.
At the time, I was quite shocked, but my wife Deborah and I were reassured, as the doctor said it was found early and had not spread.
Pioneer: Barry Dolling, 65, from South London, was the first UK person to test the procedure
My oncologist, Dr Alison Tree, said I had three options. Because the cancer was slow-growing, they could leave it and act only if the symptoms got worse, but I didn’t like the idea of it getting worse and being harder to treat.
Or I could have surgery — but I didn’t like the sound of that either as the recovery time is at least three months and it can also cause erectile dysfunction and incontinence.
The third option was to have radiotherapy, where they blast the tumour with high-energy X-rays.
Usually this carries a risk of damaging healthy tissue, but Dr Tree said she was trialling a new technique which combines radiotherapy and an MRI scanner.
Treatment: Radiographers Trina Herbert (left), and Gillian Smith help patient Barry (centre) after treatment using a Magnetic Resonance Linear Accelerator (MR Linac) machine
Doctors can target the radiation more precisely so there is less damage to healthy tissue and fewer side-effects. I was keen to give it a go.
I had my first session two weeks ago, and I’m now halfway through the trial. I will have 20 sessions in total over four weeks.
Every day, from Monday to Friday, I go to the hospital — I think the experience is pretty much the same as with standard radiotherapy. When I arrive I drink two glasses of water, which enlarge my bladder and moves it slightly out of the way so my prostate can be more easily targeted.
Then I lie on a bed attached to a large machine with a chamber. The bed slides into the chamber and I lie still for 45 minutes — this is where the radiation is delivered, but I don’t feel a thing.
The bed then slides back out, I get dressed and get on with my day. I’ve not had any side-effects so far, and I still swim, cycle and play golf at weekends.
They will wait three months before I’m given a prostate-specific antigen (PSA) blood test to see if the cancer is under control.
I was really pleased to be the first person to have this treatment, it’s amazing to think it could change how others will be treated.
I’m hopeful it will give me a better quality of life without cancer, and help avoid side-effects.