There’s a new treatment being developed to tackle cancer. A high dose, very quick radiation dose instead of lower, spread out doses. It’s called Flash, and so far it seems to kill or reduce cancer cells without hurting normal cells, or at least minimizing the collateral damage. It’s being designed in Cern.
Eleven years ago, Marie-Catherine Vozenin, a radiobiologist now working at Geneva University Hospitals (Hug), and others published a paper outlining a paradigm-shifting approach to traditional radiotherapy treatment which they called Flash. By delivering radiation at ultra-high dose rates, with exposures of less than a second, they showed that it was possible to destroy tumours in rodents while sparing healthy tissue.
Its impact was immediate. International experts described it as a seminal breakthrough, and it galvanised fellow radiobiologists around the world to conduct their own experiments using the Flash approach to treat a wide variety of tumours in rodents, household pets, and now humans.
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In recent years, animal studies have repeatedly shown that Flash makes it possible to markedly increase the amount of radiation delivered to the body while minimising the impact that it has on surrounding healthy tissue. In one experiment, healthy lab mice which were given two rounds of radiation via Flash did not develop the typical side effects which would be expected during the second round. In another study, animals treated with Flash for head and neck cancers experienced fewer side effects, such as reduced saliva production or difficulty swallowing.
Loo is cautiously optimistic that going forwards, such benefits may also translate to human patients. “Flash produces less normal tissue injury than conventional irradiation, without compromising anti-tumour efficacy – which could be game-changing,” he says. An additional hope is that this could then reduce the risk of secondary cancers, resulting from radiation-induced damage later in life, although it is still too early to know if that will be the case.
There is still a lot of development to be done:
From carbon ions to protons and electrons, there are many ways of delivering radiotherapy, each with different applications and challenges. One of the most precise forms of radiotherapy is hadron therapy, delivered with carbon ions. But there are only 14 facilities which can deliver this in the entire world, each one costing an estimated $150m (£122m). Currently this therapy is delivered using a conventional dosing regime, in which the radiation is delivered over several minutes. However, with the Flash protocol the ions would be delivered in less than a second.
“High energy electrons can be used to treat superficial tumours in the skin,” says André-Dante Durham Faivre, a radiation oncologist at Hug. “Photons, i.e. X-rays, or protons [a type of subatomic particle], can be used to treat deeper tumours, while we save carbon ions and helium particles for very specialised cases, as it’s only very, very big clinical centres that can offer that type of treatment. The particle accelerator needed to administer carbon ion radiotherapy is the size of a building.”
Because of the rarity, complexity, and size of the equipment, test subject (cancer victims) must travel to the treatment sites. I hope that if this treatment works, the particle generators needed will follow other technology, and eventually be miniaturized to the point where this becomes conventional treatment. Hopefully, it works. I’m for anything that saves patients.
And cancer is just evil.
Now Cern are working with researchers at Lausanne University Hospital and the French company TheryQ to try and develop a new form of accelerator which delivers even more radiation – described as very high energy electrons – at Flash dose rates. And according to Durham Faivre, Hug researchers are currently in discussions with commercial partners to develop an X-ray Flash machine.
Such accelerators could enable the benefits of Flash to be applied to deep tumours without requiring a vast machine, says Durham Faivre. The ultimate goal is to make it possible for any hospital with radiotherapy equipment to be able to provide Flash. “We believe that X-ray Flash machines could in time replace existing conventional X-ray machines,” he says.
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