Division of Hematology-Oncology, Department of Internal Medicine, Hallym University Sacred Heart Hospital, Anyang, Republic of Korea. Division of Hematology-Oncology, Department of Internal Medicine, Jeonbuk National University Medical School, Jeonju, Republic of Korea. Division of Hematology-Oncology, Department of Internal Medicine, CHA Bundang Medical Center, CHA University, Seongnam, Republic of Korea. Division of Hematology-Oncology, Department of Internal Medicine, Daegu Catholic University Hospital, Daegu, Republic of Korea. Division of Hematology-Oncology, Department of Internal Medicine, Pusan National University Hospital, Pusan National University School of Medicine, Busan, Republic of Korea. Division of Hematology-Oncology, Department of Internal Medicine, Inje University Busan Paik Hospital, Busan, Republic of Korea. Division of Hematology-Oncology, Department of Internal Medicine, Chungbuk National University College of Medicine, Cheongju, Republic of Korea. Division of Hemato-Oncology, Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Republic of Korea. Department of Prevention Medicine, University of Ulsan College of Medicine, Department of Clinical Epidemiology and Biostatistics, Asan Medical Center, Seoul, Republic of Korea. Department of Clinical Epidemiology and Biostatistics, Asan Medical Center, Seoul, Republic of Korea. Division of Hemato-Oncology, Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Republic of Korea. smbang7@snu.ac.kr.