1. Department of Radiation Oncology, Soonchunhyang University Seoul Hospital, Seoul, Republic of Korea
2. Department of Radiation Oncology, Ewha Womans University College of Medicine, Republic of Korea
3. Department of Radiation Oncology, Hanyang University College of Medicine, Seoul, Republic of Korea,
4. Department of Surgery, Seoul National University College of Medicine, Seoul, Republic of Korea
5. Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
6. Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Republic of Korea