1. Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, Korea.
2. Department of Palliative Care and Rehabilitation Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas.
3. Department of Thoracic Oncology, Hubei Cancer Hospital, Wuhan, China.
4. Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, Texas.