Initially, the annual meetings of the International Society of Paediatric Oncology (SIOP) served as the forum for paediatric radiation oncology. This platform, however, did not provide for optimal communication between paediatric radiation oncologists world-wide addressing,for example, the specific demands on technology, results of clinical trials including radiotherapy, and collaboration with other radiation oncology societies.
In June 2003, a meeting on paediatric radiation oncology was organized in Lyon, France. Over three days, 200 radiation oncologists involved in paediatric radiation oncology shared their experiences, and the resulting discussions between surgeons, paediatricians and radiation oncologists were most fruitful.
The success of the congress prompted the continuation of this experiment and gave rise to the Paediatric Radiation Oncology Society. As Paediatric Radiation Oncologists met regularly at the annual SIOP meetings it was planned in advance to make a formal proposal to form our own independent society and accordingly at the Vancouver, Canada, SIOP meeting in 2005 a motion was carried on 19 September 2005 to proceed to form the new organization. The founding members were doctors Christian Carrie, Carolyn Freeman, Sarah Donaldson, Roger Taylor, Patrick Thomas, Shiao Woo and Karen Goddard, with very active technical and administrative support from Thomas Garmier.
PROS was officially created in Lyon on March 1 2006, when the offical statutes were given in to the Préfecture du Rhône.