Mild temperature hyperthermia combined with carbogen breathing increases tumor partial pressure of oxygen (pO2) and radiosensitivity.

The partial pressure of oxygen (pO2) of FSaII tumors grown in the leg of C3H mice significantly improved when the tumors were heated by immersing the tumor-bearing legs in a water bath at 41.5 degrees C for 60 min. The tumor pO2 also substantially increased when the tumor-bearing mice breathed carbogen (95% O2:5% CO2). Additionally, mild hyperthermia followed by carbogen breathing further increased the tumor pO2 and increased radiation cytotoxicity as assessed by the in vivo/in vitro excision assay for surviving FSaII cells. It was concluded that mild hyperthermia in combination with carbogen breathing is potentially useful to reoxygenate radioresistant hypoxic cells and improve the radiotherapy of human tumors.