1 Department of Endoscopy, Respiratory Endoscopy Division, National Cancer Center Hospital, 5-1-1, Tsukiji, Chuo-ku, Tokyo, Japan. Electronic address: honorific2006@yahoo.co.jp.
2 Department of Endoscopy, Respiratory Endoscopy Division, National Cancer Center Hospital, 5-1-1, Tsukiji, Chuo-ku, Tokyo, Japan.
3 Department of Endoscopy, Respiratory Endoscopy Division, National Cancer Center Hospital, 5-1-1, Tsukiji, Chuo-ku, Tokyo, Japan; Department of Thoracic Oncology, National Cancer Center Hospital, 5-1-1, Tsukiji, Chuo-ku, Tokyo, Japan.