Shedding light on Proton Beam Therapy cancer treatment

Proton beam therapy is hailed by some as the new wonder-treatment for complex cancers. But is it suitable for everyone? Lisa Salmon finds out

Proton Beam Therapy is only by one facility in the UK, in the Wirral area of England, with more currently under construction

IT'S understandable that most people diagnosed with cancer will want to ensure they're getting the best treatment available. In 2014 the story of five-year-old brain tumour patient Ashya King put proton beam therapy (PBT) in the spotlight, after his parents took him out of the Southampton hospital where he was being treated, sparking an international manhunt, in a bid to get PBT for their son abroad.

Ashya finally had the treatment in Prague, and last year his father Brett said his son was cancer-free.

At present, PBT is only available at one centre in the UK – and only for treating rare eye cancers, though other centres are under construction, so it should eventually be more widely available.

Most conventional radiotherapy treatments use X-rays (photons) to damage cancer cells so they can't multiply and will die. But X-rays don't discriminate between cancerous and healthy tissue, and can carry on through the tumour and destroy normal cells near it, causing serious side-effects.

This is particularly harmful for children, as they're still developing and are more susceptible to the effects of radiation. They're also slightly more at risk of developing another cancer later in life, due to early radiation exposure.

Zapping tumours with protons – positively-charged particles found in the centre of atoms – offers the chance to avoid such risks, as they can damage cancer cells in the same way as conventional radiotherapy, but stop once they hit their target.

This means there's less chance of damaging surrounding healthy tissues, reducing side-effects.

As Dr Jiri Kubes, medical director at the Proton Therapy Center in Prague, puts it: "Proton therapy maximises curability while significantly minimising the risk of possible side-effects, ultimately preserving patients' quality of life."

A US study published last year found PBT caused fewer side-effects in children than conventional radiotherapy. Researchers from Massachusetts General Hospital studied 59 patients aged between three and 21 and found that after five years, the children's survival rate was similar to that of patients treated with conventional radiotherapy, but there were fewer side-effects to the heart and lungs.

"Since it delivers a lower dose of radiation to surrounding tissues, proton beam therapy's main advantage is in reducing side-effects, rather than improving survival or cure," Oncologist Adrian Crellin, NHS England's clinical lead on proton beam therapy.

However, the reduced risk of side-effects potentially means that treatment can be delivered in higher doses too – and this, Dr Crellin notes, might mean some cancers can be dealt with more effectively.

"It's critical to stress that for most patients right now, there's no strong evidence that proton beam radiotherapy is 'better' at curing cancer, or improving a patient's chances of survival, than conventional X-ray radiotherapy, " says Dr Crellin, who points out that much more research into PBT is needed.

Dr Kubes explains the success rate for proton therapy is highly dependent on the exact diagnosis.

"For some diagnoses, such as prostate cancer, paranasal sinus cancer or base of skull tumours, proton therapy is much better than conventional photon radiotherapy," Dr Kubes says.

"For other diagnoses, protons are only slightly better but with a reduction of side-effects."

He adds: "Overall, the main advantage of proton therapy is the preservation of quality of life."

Cancer Research UK says around 1 per cent of people who currently receive radiotherapy will be eligible for PBT – equating to about 1,500 patients a year.

The treatment is particularly suitable for specific, complex childhood cancers, as well as some very rare cancers, including tumours affecting the base of the skull or the spine.

Patients have been able to access PBT abroad since 2008 through the NHS Proton Overseas Programme. To get funding – which pays for travel and accommodation as well as the treatment – patients have to meet special NHS criteria after being referred to a panel of clinical experts by their specialist.

So far, more than 800 patients have been approved through the programme, 70 per cent of whom have been children. The average cost is around £90,000 per person. If patients fail to obtain NHS finding, there is the option to pay for treatment themselves, with many now turning to crowdfunding and public donations.

Dr Kubes says the number of UK enquiries regarding treatment at the Proton Therapy Center in Prague is growing, and now stands at around 60-80 per month.

"Raising awareness about proton therapy for the general public, as well as within the medical community in the UK, has been a challenge," he says. "I believe proton therapy should be considered a viable treatment option for some diagnoses and, for those, offered as a standard procedure."

As only a small number of UK specialists have practical experience with PBT, Dr Kubes thinks they may be reluctant to give information to patients about the treatment. "The approach to proton therapy in the UK is changing though – several centres are presently under construction, and I believe the UK could become a leading country in the proton therapy field," he adds.

Cancer Research UK points out it's 'important to remember that the treatment isn't a 'magic bullet' and won't be suitable for everyone'. Plus, although it looks like proton beam therapy has fewer side-effects than conventional radiotherapy, it still carries some risks and uncertainties.

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