“…After pioneering work by Swedish scientists in the early and mid 1990s [3,4], its use has grown considerably, however, still without a solid scientific evidence-base. In order to evaluate the current knowledge and technology and facilitate the creations of multi-institutional and co-operative group studies, acquiring sufficient scientific evidence, a 3 rd Acta Oncologica Symposium was organized in Copenhagen June 15 Á17, 2006 [5,6]. A broad international faculty constituting the key persons participated and produced 29 original articles published in a special issue of Acta Oncologica within an exceptionally short time period.…”