Ashya King, a five-year-old British boy with brain tumour, leaves in an ambulance after finishing his treatment at the Proton Therapy Centre in Prague October 24, 2014. King had his first treatment on September 15 after his parents, Naghemeh and Brett King, attracted international attention by removing him from hospital in Britain against medical advice. The couple left Britain with their son at the end of August, saying they wanted to take him to the clinic in Prague as proton beam therapy is not currently available in Britain. King's parents were detained in Spain after an international manhunt that drew condemnation from the British media, separated from their sick son and then released days later by a Spanish judge. REUTERS/Rene Volfik (CZECH REPUBLICHEALTH - Tags: POLITICS HEALTH) 

An ambulance is seen as Ashya King (not pictured), a five-year-old British boy with brain tumour, leaves after finishing his treatment at the Proton Therapy Centre in Prague October 24, 2014. King had his first treatment on September 15 after his parents, Naghemeh and Brett King, attracted international attention by removing him from hospital in Britain against medical advice. The couple left Britain with their son at the end of August, saying they wanted to take him to the clinic in Prague as proton beam therapy is not currently available in Britain. King's parents were detained in Spain after an international manhunt that drew condemnation from the British media, separated from their sick son and then released days later by a Spanish judge REUTERS/Rene Volfik (CZECH REPUBLIC - Tags: POLITICS HEALTH) 

Ashya King, a five-year-old British boy with brain tumour, leaves with his mother Naghemeh after finishing his treatment at the Proton Therapy Centre in Prague October 24, 2014. King had his first treatment on September 15 after his parents, Naghemeh and Brett King, attracted international attention by removing him from hospital in Britain against medical advice. The couple left Britain with their son at the end of August, saying they wanted to take him to the clinic in Prague as proton beam therapy is not currently available in Britain. King's parents were detained in Spain after an international manhunt that drew condemnation from the British media, separated from their sick son and then released days later by a Spanish judge. REUTERS/Rene Volfik (CZECH REPUBLIC - Tags: POLITICS HEALTH) 

Ashya King, a 5-year-old British boy with brain tumour, leaves after finishing his treatment at the Proton Therapy Centre in Prague October 24, 2014. King had his first treatment on September 15 after his parents, Naghemeh and Brett King, attracted international attention by removing him from hospital in Britain against medical advice. The couple left Britain with their son at the end of August, saying they wanted to take him to the clinic in Prague as proton beam therapy is not currently available in Britain. King's parents were detained in Spain after an international manhunt that drew condemnation from the British media, separated from their sick son and then released days later by a Spanish judge REUTERS/Rene Volfik (CZECH REPUBLIC - Tags: POLITICS HEALTH) 

Ashya King, a five-year-old British boy with brain tumour, leaves with his mother Naghemeh (3rd R) after finishing his treatment at the Proton Therapy Centre in Prague October 24, 2014. King had his first treatment on September 15 after his parents, Naghemeh and Brett King, attracted international attention by removing him from hospital in Britain against medical advice. The couple left Britain with their son at the end of August, saying they wanted to take him to the clinic in Prague as proton beam therapy is not currently available in Britain. King's parents were detained in Spain after an international manhunt that drew condemnation from the British media, separated from their sick son and then released days later by a Spanish judge. REUTERS/Rene Volfik (CZECH REPUBLIC - Tags: POLITICS HEALTH TPX IMAGES OF THE DAY) 

Ashya King, a 5-year-old British boy with brain tumor, leaves after finishing his treatment at the Proton Therapy Centre in Prague October 24, 2014. King had his first treatment on September 15 after his parents, Naghemeh and Brett King, attracted international attention by removing him from hospital in Britain against medical advice. The couple left Britain with their son at the end of August, saying they wanted to take him to the clinic in Prague as proton beam therapy is not currently available in Britain. King's parents were detained in Spain after an international manhunt that drew condemnation from the British media, separated from their sick son and then released days later by a Spanish judge. REUTERS/Rene Volfik (CZECH REPUBLIC - Tags: HEALTH POLITICS TPX IMAGES OF THE DAY) 

A safety ring is seen on a boat, made with plastic bottles, in Nymburk July 12, 2014. Jan Kara, a 22-year-old student, and Jakub Bures, a 22-year-old car mechanic, built the 10-metre (32.8-feet) long boat from 5000 plastic bottles strapped to a wooden frame. The four men plan to pedal from their hometown Nymburk down the river Elbe to Hamburg in Germany to draw attention to an increasing plastic pollution in Europe, they said. Picture taken July 12, 2014. REUTERS/Rene Volfik (CZECH REPUBLIC - Tags: ENVIRONMENT SOCIETY TRANSPORT) 

Jakub Bures, Jan Kara, Jan Brand and Jan Holan pedal their boat, made with plastic bottles, on the Elbe river in Nymburk July 12, 2014. Kara, a 22-year-old student and Bures, a 22-year-old car mechanic, built the 10-metre (32.8-feet) long boat from 5000 plastic bottles strapped to a wooden frame. The four men plan to pedal from their hometown Nymburk down the river Elbe to Hamburg in Germany to draw attention to an increasing plastic pollution in Europe, they said. Picture taken July 12, 2014. REUTERS/Rene Volfik (CZECH REPUBLIC - Tags: ENVIRONMENT SOCIETY TRANSPORT TPX IMAGES OF THE DAY) 

People stand on a bridge as Jakub Bures, Jan Kara, Jan Brand and Jan Holan pedal their boat, made with plastic bottles, on the Elbe river in Nymburk July 12, 2014. Kara, a 22-year-old student and Bures, a 22-year-old car mechanic, built the 10-metre (32.8-feet) long boat from 5000 plastic bottles strapped to a wooden frame. The four men plan to pedal from their hometown Nymburk down the river Elbe to Hamburg in Germany to draw attention to an increasing plastic pollution in Europe, they said. Picture taken July 12, 2014. REUTERS/Rene Volfik (CZECH REPUBLIC - Tags: ENVIRONMENT SOCIETY TRANSPORT) 

People wave as Jakub Bures, Jan Kara, Jan Brand and Jan Holan pedal their boat, made with plastic bottles, during an official launch on the Elbe river in Nymburk July 12, 2014. Kara, a 22-year-old student and Bures, a 22-year-old car mechanic, built the 10-metre (32.8-feet) long boat from 5000 plastic bottles strapped to a wooden frame. The four men plan to pedal from their hometown Nymburk down the river Elbe to Hamburg in Germany to draw attention to an increasing plastic pollution in Europe, they said. Picture taken July 12, 2014. REUTERS/Rene Volfik (CZECH REPUBLIC - Tags: ENVIRONMENT SOCIETY TRANSPORT) 

People look on as Jakub Bures, Jan Kara, Jan Brand and Jan Holan pedal their boat, made with plastic bottles, during an official launch on the Elbe river in Nymburk July 12, 2014. Kara, a 22-year-old student and Bures, a 22-year-old car mechanic, built the 10-metre (32.8-feet) long boat from 5000 plastic bottles strapped to a wooden frame. The four men plan to pedal from their hometown Nymburk down the river Elbe to Hamburg in Germany to draw attention to an increasing plastic pollution in Europe, they said. Picture taken July 12, 2014. REUTERS/Rene Volfik (CZECH REPUBLIC - Tags: ENVIRONMENT SOCIETY TRANSPORT) 

People walk across a bridge as Jakub Bures, Jan Kara, Jan Brand and Jan Holan pedal their boat, made with plastic bottles, on the Elbe river in Nymburk July 12, 2014. Kara, a 22-year-old student and Bures, a 22-year-old car mechanic, built the 10-metre (32.8-feet) long boat from 5000 plastic bottles strapped to a wooden frame. The four men plan to pedal from their hometown Nymburk down the river Elbe to Hamburg in Germany to draw attention to an increasing plastic pollution in Europe, they said. Picture taken July 12, 2014. REUTERS/Rene Volfik (CZECH REPUBLIC - Tags: ENVIRONMENT SOCIETY TRANSPORT)