Würschmidt F, Beck-Bornholdt H P, Vogler H, Jung H
Institute of Biophysics and Radiobiology, University of Hamburg, FRG.
Strahlenther Onkol. 1991 Jan;167(1):26-30.
Fractionated split-course treatments were given with gaps of different length and the effects on tumor response was studied using the rhabdomyosarcoma R1H of the rat. Total doses of 68, 75 and 82 Gy were applied in 30 fractions (five fractions per week). After four weeks, that is after 20 fractions, treatment was interrupted for one or two weeks followed by another ten fractions. The results were compared to those of continuous treatment given in six consecutive weeks. Tumor response was quantified by TCD37% and net growth delay. The TCD37% increased with increasing duration of the gap. A mean repopulated dose of 0.72 Gy per day was obtained. This corresponds to a doubling time of tumor clonogens of 4.2 days during the gap, which is somewhat slower than the volume doubling time of unperturbed tumors (2.5 days) of the same size. The results obtained for the net growth delay support the results of the TCD37% data. It is concluded that a gap during fractionated radiotherapy leads to poorer results since the dose required for tumor control is enhanced and sparing of normal tissue can only be expected for early but not for late reacting tissues.
采用不同长度间隔的分次分割疗程进行治疗，并使用大鼠横纹肌肉瘤R1H研究其对肿瘤反应的影响。总剂量68、75和82 Gy分30次给予（每周5次）。4周后，即20次照射后，治疗中断1或2周，随后再进行10次照射。将结果与连续6周进行的连续治疗结果进行比较。通过肿瘤控制剂量37%（TCD37%）和净生长延迟来量化肿瘤反应。TCD37%随间隔时间的延长而增加。获得了每天0.72 Gy的平均再增殖剂量。这对应于间隔期肿瘤克隆原细胞的倍增时间为4.2天，这比相同大小未受干扰肿瘤的体积倍增时间（2.5天）略慢。净生长延迟的结果支持了TCD37%数据的结果。得出的结论是，分次放疗期间的间隔会导致较差的结果，因为控制肿瘤所需的剂量增加，并且仅对早期反应组织而非晚期反应组织有望实现正常组织的 sparing。 （注：“sparing”此处暂未准确合适中文对应，保留英文）
