Zywietz F, Reeker W, Kochs E
Institute of Biophysics and Radiobiology, University Hospital Eppendorf, Hamburg, Germany.
Int J Radiat Oncol Biol Phys. 1997 Jan 1;37(1):155-62. doi: 10.1016/s0360-3016(96)00465-8.
To determine the influence of adjuvant hyperthermia on the oxygenation status of fractionated irradiated tumors.
Oxygen partial pressure (pO2) in rat rhabdomyosarcomas (R1H) was measured sequentially at weekly intervals during a fractionated irradiation with 60Co-gamma-rays (60 Gy/20f/4 weeks) in combination with local hyperthermia (8 f(HT) at 43 degrees C, 1 h/4 weeks). Tumors were heated twice weekly with a 2450 MHz microwave device at 43 degrees C, 1 h starting 10 min after irradiation. The pO2 measurements (pO2-histograph, Eppendorf, Germany) were performed in anesthetized animals during mechanical ventilation and in hemodynamic steady state. All tumor pO2 measurements were correlated to measurements of the arterial oxygen partial pressure (paO2) determined by a blood gas analyzer.
The oxygenation status of R1H tumors decreased continuously from the start of the combined treatment, with increasing radiation dose and number of heat fractions. In untreated controls a median tumor pO2 of 23 +/- 2 mmHg (mean +/- SEM) was measured. Tumor pO2 decreased to 11 +/- 2 mmHg after 30 Gy + 4 HT (2 weeks), and to 6 +/- 2 mmHg after 60 Gy + 8HT (4 weeks). The increase in the frequency of pO2-values below 5 mmHg and the decrease in the range of the pO2 histograms [delta p(10/90)] further indicated that tumor hypoxia increased relatively rapidly from the start of combined treatment. After 60 Gy + 8HT 48 +/- 5% (mean +/- SEM) of the pO2-values recorded were below 5 mmHg.
These findings suggest that adjuvant hyperthermia to radiotherapy induces greater changes in tumor oxygenation than radiation alone [cf. (39)]. This might be of importance for the temporary application of hyperthermia in the course of a conventional radiation treatment.
确定辅助热疗对分次照射肿瘤氧合状态的影响。
在60Co-γ射线分次照射（60 Gy/20次/4周）联合局部热疗（43℃，1小时/4周，共8次热疗）期间，每周依次测量大鼠横纹肌肉瘤（R1H）中的氧分压（pO2）。肿瘤每周用2450 MHz微波设备加热两次，在照射后10分钟开始，43℃，持续1小时。pO2测量（pO2直方图，德国艾本德公司）在机械通气且血流动力学稳定状态下的麻醉动物中进行。所有肿瘤pO2测量值均与通过血气分析仪测定的动脉氧分压（paO2）测量值相关。
从联合治疗开始，随着辐射剂量和热疗次数的增加，R1H肿瘤的氧合状态持续下降。在未治疗的对照组中，测得肿瘤pO2中位数为23±2 mmHg（平均值±标准误）。30 Gy + 4次热疗（2周）后肿瘤pO2降至11±2 mmHg，60 Gy + 8次热疗（4周）后降至6±2 mmHg。pO2值低于5 mmHg的频率增加以及pO2直方图范围的减小[δp(10/90)]进一步表明，从联合治疗开始肿瘤缺氧相对迅速增加。60 Gy + 8次热疗后，记录的pO2值中有48±5%低于5 mmHg。
这些发现表明，放疗联合辅助热疗比单纯放疗引起肿瘤氧合状态的变化更大[参见(39)]。这对于在传统放疗过程中临时应用热疗可能具有重要意义。
