1. Department of Family Medicine, Dongguk University Ilsan Hospital, Goyang-si, South Korea
2. Department of Palliative Medicine, Tohoku University School of Medicine, Sendai, Japan
3. Department of Palliative Medicine, Takeda General Hospital, Aizuwakamatsu, Japan
4. Department of Medicine, Dongguk University Medical School, Seoul, South Korea
5. Department of Statistics, Dongguk University-Seoul, Seoul, South Korea
6. Division of Hematology and Medical Oncology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam-si, South Korea
7. Division of Medical Oncology, Bundang Medical Center, CHA University, Seongnam-si, South Korea
8. Division of Medical Oncology, Department of Internal Medicine, Yonsei University College of Medicine, Yonsei Cancer Center, Seoul, South Korea