[1] Hakodate Municipal Hosp, Dept Internal Med, Hakodate, Hokkaido 0418680, Japan
[2] Hokkaido Univ, Grad Sch Med, Dept Hematol & Oncol, Sapporo, Hokkaido, Japan
[3] Hokkaido Univ, Grad Sch Med, Dept Gastroenterol, Sapporo, Hokkaido, Japan
[4] Asahikawa Municipal Hosp, Dept Internal Med, Asahikawa, Hokkaido, Japan
[5] Natl Canc Ctr, Dept Hematol, Sapporo, Hokkaido, Japan
[6] Sapporo Kosei Hosp, Dept Internal Med, Sapporo, Hokkaido, Japan
[7] Aiiku Hosp, Dept Internal Med, Sapporo, Hokkaido, Japan
[8] Obihiro Kosei Hosp, Dept Internal Med, Obihiro, Hokkaido, Japan