Doctors told police that Ashya's life was in "grave danger" and that he had only months to live-which is why his parents were looking for better treatment elsewhere.
Ashya, 5, was being treated with radiotherapy at Southampton General Hospital, but his parents took him abroad to have proton beam therapy, a highly-targeted form of radiotherapy that doesn't destroy the surrounding tissues.
As Cancer Research UK states, standard radiotherapy is particularly harmful for children, and especially those being treated for brain tumours. Their bodies are more susceptible to the effects of radiation, and they are also more likely to develop a second cancer later in life.
Proton beam therapy isn't an alternative treatment, or a particularly controversial one. In fact, the UK government has set a lb30m budget on developing newer radiotherapy procedures, such as proton beam. Right now, it's available at one centre in Merseyside, but only for people with a rare form of eye cancer.
Otherwise, people have to travel abroad and pay for the treatment themselves-which is exactly what Ashya's parents were trying to do.