1. Center for Colorectal Cancer, National Cancer Center, Gyeonggi-do, Korea.
2. Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
4. Department of General Surgery, Yonsei University College of Medicine, Seoul, Korea.
5. Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, Korea.
6. Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea.