1. Department of Palliative Medicine, Tohoku University School of Medicine, Japan
2. Division of Biostatistics, Tohoku University Graduate School of Medicine, Japan
3. Department of Palliative Care, Tokyo Metropolitan Cancer & Infectious Diseases Center Komagome Hospital, Japan
4. Department of Palliative Medicine, Kobe University Graduate School of Medicine, Japan
5. Department of Medical Oncology, Yamaguchi-Ube Medical Center, Japan
6. Division of Medical Oncology, Department of Internal Medicine, Teikyo University School of Medicine, Japan
7. Division of Pulmonary Medicine, Department of Internal Medicine, Jichi Medical University, Japan