PROTON BEAM THERAPY: THE FACTS

PROTON beam therapy is a form of radiotherapy and, like all radiotherapy, it works by damaging cancer cells’ DNA. 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.

IT’S HOPED that the two NHS proton beam centres due to be operational by 2020 — one in London, one in Manchester — will treat 1,500 patients a year. Currently, the NHS sends about 100 people abroad for the treatment.

ONE in 100 people with cancer would be suitable for proton beam therapy, according to Cancer Research UK, although some experts have suggested it could be as many as one in ten of those who receive conventional radiotherapy currently. It is only suitable for solid tumours rather than blood cancers such as leukaemia — and, according to the NHS, 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 Manchester sits in a bunker reinforced with timber, steel and concrete. THE treatment itself is usually painless.