Clinical development of irinotecan (CPT-11) in lung cancers : -CPT-11 Co-operative Study Group for Lung Cancer in Japan- H. Niitani1), M. Fukuoka2), K. Nagao3). 1)Nippon Medical School, Bunkyo-ku, Tokyo, Japan. 2)Osaka General Hospital, Osaka, Japan. 3)Chiba University, Chuo-ku, Chiba, Japan