Twentyman P R
Br J Cancer. 1977 Feb;35(2):208-17. doi: 10.1038/bjc.1977.28.
Growth curve measurements on the EMT6 tumour following treatment with cyclophosphamide indicate a growth delay of about 3 days for each 100 mg/kg of the drug. Tumours treated whilst still microscopic show a rather longer delay for the same dose. Data for the surviving fraction of cells in the tumours measured by in vitro plating at 2 h after cyclophosphamide are not compatible with the measured growth delay and realistic values for the doubling times of surviving clonogenic cells; It is concluded that there is considerable "repair of potentially lethal damage", and that there is probably no single time after cyclophosphamide treatment at which the surviving fraction of cells can be correctly measured by the in vitro plating technique. Cell loss from cyclophosphamide-treated tumours is increased only slightly over that from untreated tumours, and the regeneration of surviving cells is very rapid. In this situation, only marginal regressions in tumour volume are caused by the highest doses of the drug.
用环磷酰胺治疗EMT6肿瘤后的生长曲线测量表明，每100mg/kg药物可使肿瘤生长延迟约3天。在肿瘤仍为微观状态时进行治疗，相同剂量下延迟时间会更长。环磷酰胺给药2小时后通过体外接种测量的肿瘤中存活细胞分数的数据，与测量的生长延迟以及存活克隆细胞的实际倍增时间值不相符；得出的结论是，存在相当程度的“潜在致死性损伤修复”，并且在环磷酰胺治疗后可能不存在一个能通过体外接种技术正确测量细胞存活分数的单一时间点。环磷酰胺处理的肿瘤细胞损失仅比未处理的肿瘤略有增加，存活细胞的再生非常迅速。在这种情况下，该药物的最高剂量仅导致肿瘤体积出现轻微缩小。
