[1] Hiroshima Univ, Hiroshima, Japan
[2] Hiroshima Univ Hosp, Hiroshima, Japan
[3] Japanese Study Grp Pediat Liver Tumor, Hiroshima, Japan
[4] Kyoto Prefectural Univ Med, Grad Sch Med Sci, Dept Pediat, Kyoto, Japan
[5] Japanese Study Grp Pediat Liver Tumor, Osaka, Japan
[6] Japanese Study Grp Pediat Liver Tumor, Tokyo, Japan
[7] Japanese Study Grp Pediat Liver Tumor, Saitama, Japan
[8] Japanese Study Grp Pediat Liver Tumor, Yokohama, Kanagawa, Japan