PROTON BEAM THERAPY: THE FACTS
PROTON beam therapy is a form of radiotherapy and, like all radiotherapy, it works by damaging the DNA in cancer cells. The difference is that the proton beam of radiation only releases its energy when it hits the cancerous tissue; it then stops, meaning less damage to surrounding tissue.
This is why it’s thought to be more suitable for cancers in particularly vulnerable areas, such as the brain.
THE tiny particles — called protons — that destroy the cancer cells are ‘accelerated’ in huge machines to a speed of 100,000 miles per second to create the high-energy beam.
ONE in 100 people with cancer would be suitable for proton beam therapy, according to cancer experts, although some have suggested it could be as many as one in ten of those who currently receive conventional radiotherapy.
It is only suitable for solid tumours rather than blood cancers such as leukaemia — and, according to the experts, is considered most suitable for tumours in the brain or spine, or complex childhood cancers, where the risk of serious side-effects is greatest.
A TREATMENT session generally takes 15 to 45 minutes, similar to radiotherapy.
THE machine that generates the protons is huge. Called a cyclotron (the one pictured here is at the Prague cancer centre where Ashya King was treated), it weighs 90 tonnes.
Installing it requires digging a hole approximately 30 metres deep to house the equipment and the construction of concrete walls to encase it. The one in ts in Manchester sits in a bunker reinforced with timber, steel and concrete.
THE treatment itself is usually painless.
Because, so far, there is no data to suggest it is any better at actually killing the cancer or improving survival rates.
‘It isn’t a miracle cure,’ says Dr Alford. ‘It might have a lower risk of side-effects, but this doesn’t mean it is more likely to destroy the cancer.’
Simon came across proton beam therapy while researching alternative treatments for his prostate cancer.
The diagnosis itself had come as a shock.
‘I went to see my GP because I was feeling stressed and run down in July last year,’ says Simon, who lives with his partner Maria, 40, and their two sons from previous relationships, both aged 11.
Tests revealed Simon’s level of prostate-specific antigen (PSA) — a protein produced by the prostate
— was raised, which can be an indicator of cancer. So he was referred for a biopsy. ‘Two months later, I was told I had a form of prostate cancer that was likely to grow and spread, and so it could not be left untreated,’ says Simon. ‘I couldn’t believe I’d been dealt another cancer blow,’ he says. ‘I was quite tearful. But after the initial shock I picked myself up and considered my options. I remembered the story of Ashya King. I’d read that proton beam therapy did not damage so much of the healthy tissue and I contacted the Prague clinic which treated Ashya.’ Simon had been about to book at the Prague clinic when he saw an online advert for the Rutherford Cancer Centre, which was only about a 30-minute drive from his home and due to open soon. He explains: ‘I met the oncology team in January this year and I was told I would have a session every weekday morning for 20 days. ‘They said that after a daily dose of proton beam therapy, I could just get on with my normal life. It sounded amazing.’ The downside was the cost — more than €74,000. Fortunately, Simon’s younger brother John, 54, who runs a property company with him, offered to lend him most of the money. ‘I tried other ways of raising the money and even asking if the NHS would pay, without any luck,’ says Simon. ‘I was really touched by John’s gesture.’ Before beginning the treatment, Simon had a short course of hormones to reduce his testosterone levels, as this can drive cancer growth. (It is typically given to men who have conventional radiotherapy, too.) For the proton beam therapy, first a CT scan is carried out to make sure the beam will hit the correct spot. The beam is then delivered via a device mounted on a gantry above the patient. ‘The first time, I didn’t even realise it had happened,’ says Simon. ‘I soon learnt that the faint clicking sound that lasted 30 seconds was the proton beam being fired, but I still didn’t feel a thing.’
TOWARDS the end of his treatment, Simon suffered some slight side-effects — struggling to urinate and feeling more tired than normal. However, these went away within two weeks of finishing the course.
‘The side-effects were so much less than with the radiotherapy I had for my other cancer,’ says Simon.
‘It really didn’t have a major impact on my life like before.’
Simon will not know if the treatment has worked until next month, when he has another PSA test.
Although there is not yet a depth of studies, proton beam is ‘at least as effective as conventional radiotherapy when it comes to curing some prostate cancer’, according to Dr Jason Lester, a consultant clinical oncologist and Simon’s consultant.
‘There is evidence to show proton beam therapy is safe in prostate cancer patients and is a good treatment option for some, depending on how aggressive it [the cancer] is,’ he says.
‘It results in reduced radiation in normal healthy tissue around the prostate.
‘We hope this will translate into fewer long-term side-effects.’
So will proton beam one day be the norm for treating cancer?
‘Conventional radiotherapy does a very good job at treating a number of cancers and is an invaluable treatment,’ says Dr Alford.
‘For many cancers, the cost of proton beam therapy wouldn’t be justified.’
Simon, meanwhile, is feeling positive. ‘As treatment for cancer goes, it could not have gone better,’ he says. ‘It’s now just a case of fingers crossed until my next appointment.’