1. Department of Hematology; Sapporo Hokuyu Hospital; Sapporo Japan
2. Health Care Center; Hokkaido University; Sapporo Japan
3. Department of Hematology; NTT Higashinihon Sapporo Hospital; Sapporo Japan
4. Department of Hematology; Hokkaido University Hospital; Sapporo Japan
5. Department of Hematology; Tokyo Women's Medical University Hospital; Tokyo Japan