Shipley W U, Stanley J A, Steel G G
Cancer Res. 1975 Sep;35(9):2488-93.
Tumor cell survival characteristics were assessed following 60Co gamma-irradiation of the Lewis lung carcinoma as 500-cu mm s.c. tumors or as 0.5-cu mm (1 mm in diameter) pulmonary metastases. Cells in the small pulmonary tumors were markedly more radiosensitive (D0 = 106 rads; hypoxic fraction less than 0.005) than were those in large s.c. tumors (final D0, 315 rads; hypoxic fraction, 0.36). When pulmonary metastases were excised and irradiated intact under well-oxygenated conditions in vitro, the hypoxic fraction rose to 0.30. This implies that, under normal in situ conditions, these nodules contain a microvascular system that achieves adequate oxygen supply to the great majority of tumor cells. Thus, the tumor cells within these small metastatic implants were more sensitive to irradiation, largely due to better oxygenation, and may be more sensitive to chemotherapy, due to better drug availability.
在将Lewis肺癌作为500立方毫米的皮下肿瘤或0.5立方毫米（直径1毫米）的肺转移瘤进行60Coγ射线照射后，评估肿瘤细胞的存活特性。小的肺肿瘤中的细胞比大的皮下肿瘤中的细胞对放射明显更敏感（D0 = 106拉德；乏氧分数小于0.005）（最终D0为315拉德；乏氧分数为0.36）。当肺转移瘤在体外充分氧合的条件下完整切除并照射时，乏氧分数升至0.30。这意味着，在正常原位条件下，这些结节含有一个微血管系统，可为绝大多数肿瘤细胞提供充足的氧气供应。因此，这些小的转移植入物中的肿瘤细胞对照射更敏感，主要是因为氧合更好，并且由于药物可及性更好，可能对化疗也更敏感。
