Three ways to make proton therapy affordable

If cost was not an issue, proton therapy would be the treatment of choice for most patients with localized tumours. Protons can be targeted more precisely than X-rays, so the tissues around the tumour receive two to three times less radiation. This lowers the chance of causing secondary tumours or impairing white blood cells and the immune system. High doses of protons can be delivered safely to hard-to-treat tumours: for instance, those at the base of the skull or in the liver. Such accuracy is crucial when treating cancers in children. Yet most hospitals do not offer proton therapy. The equipment is huge and expensive. Housed in multistorey buildings with halls the size of tennis courts, one proton centre with 2–3 treatment rooms typically costs more than US$100 million to build. To reach deep-seated tumours, the protons must be sped up to 60% of the speed of light (a kinetic energy of 235 mega electronvolts; MeV) using a particle accelerator, such as a cyclotron or synchrotron. Rotatable gantries with wheels typically 10 metres across and weighing 100–200 tonnes direct the protons at the patient from a range of angles. Concrete shields, metres thick, are necessary to block stray neutrons. “Nothing so big and so useless has ever been discovered in medicine,” said Amitabh Chandra, director of health policy research at the John F. Kennedy School of Government at Harvard University in Cambridge, Massachusetts. He has compared a protontherapy system to the Death Star from Star Wars. Nonetheless, there are now more than 60 proton-therapy centres around the world, B S IP /U IG /G ET TY