小细胞未分化型肺癌约占肺癌的1/10～1/3,在尸检中发现约占1/5～1/4,据爱丁堡胸外科医院400名肺癌患者中39.8%为未分化癌,鳞癌47.5%,腺癌5.1%,肺泡细胞癌0.4%,混合细胞癌1.4%。岗田氏临床统计517例肺癌未分化癌占22%。日坛医院胡豫氏根据手术标本的统计未分化癌占 Small-cell undifferentiated lung cancer accounts for about 1/10 to 1/3 of lung cancer, and it is found in autopsy about 1/5 to 1/4. According to the Edinburgh Thoracic Surgery Hospital, 39.8% of 400 lung cancer patients are undifferentiated carcinomas. 47.5% of cancer, 5.1% of adenocarcinoma, 0.4% of alveolar cell carcinoma, and 1.4% of mixed cell carcinoma. Gangtian’s clinical statistics of 517 lung cancer patients with undifferentiated cancer accounted for 22%. Hutan’s analysis of surgical specimens by undifferentiated cancers