[1] Jichi Med Univ Sch Med, Dept Pediat, Shimotsuke, Tochigi, Japan
[2] Kagoshima Univ, Grad Sch Med & Dent Sci, Dept Pediat, Kagoshima, Japan
[3] Tokyo Univ Hosp, Dept Pediat, Tokyo, Japan
[4] Okayama Univ Hosp, Dept Pediat, Okayama, Japan
[5] Shinshu Univ Sch Med, Dept Pediat, Matsumoto, Nagano, Japan
[6] Sapporo Med Univ Hosp, Dept Pediat, Sapporo, Hokkaido, Japan
[7] Hiroshima Red Cross Hosp, Dept Pediat, Hiroshima, Japan
[8] Atom Bomb Survivors Hosp, Hiroshima, Japan
[9] Miyagi Childrens Hosp, Dept Hematol & Oncol, Sendai, Miyagi, Japan
[10] Chiba Univ, Dept Pediat, Grad Sch Med, Chiba, Japan
[11] Natl Ctr Child Hlth & Dev, Childrens Canc Ctr, Tokyo, Japan