[1] Univ Gothenburg, Sahlgrenska Acad, Inst Clin Sci, Dept Pediat, Gothenburg, Sweden
[2] Sahlgrens Univ Hosp, Reg Vastra Gotaland, Dept Pediat Oncol, Gothenburg, Sweden
[3] Univ Gothenburg, Sahlgrenska Acad, Sch Publ Hlth & Community Med, Inst Med, Gothenburg, Sweden
[4] Univ Gothenburg, Sahlgrenska Acad, Inst Clin Sci, Dept Surg,SSORG Scandinavian Surg Outcomes Res Grp, Gothenburg, Sweden
[5] Sahlgrens Univ Hosp, Reg Vastra Gotaland, Dept Surg, Gothenburg, Sweden
[6] Queen Silvia Childrens Hosp, Barncancercentrum, S-41685 Gothenburg, Sweden