1. Department of Endoscopy, Respiratory Endoscopy Division/Department of Thoracic Oncology, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan
2. Division of Respiratory Medicine, Department of Internal Medicine, Sarawak General Hospital, Kuching, Malaysia
3. Department of Endoscopy, Respiratory Endoscopy Division, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan