RADIOBIOLOGICAL HYPOXIA IN THE KHT SARCOMA - PREDICTIONS USING THE EPPENDORF HISTOGRAPH

Purpose: To investigate whether electrode measurements of tumor oxygen ation obtained under a range of different treatment conditions designe d to alter the degree of tumor hypoxia could be correlated with estima tes of radiobiological hypoxia measured under the same conditions. Met hods and Materials: Experiments were performed in restrained, nonanest hetized, female C3H/He mice, which had similar to 0.5 g KHT sarcomas g rowing intramuscularly in the hind limbs, The treatments used to modif y tumor oxygenation status included breathing gas mixtures of varying oxygen content, altering tumor blood Bow, and shifting the hemoglobin oxygen dissociation curve, Radiobiological hypoxic fraction was estima ted using the paired survival curve assay, while electrode measurement s of tumor oxygenation were obtained with an Eppendorf histograph. Res ults: With the selected manipulations it was possible to vary the radi obiological hypoxic fraction in the tumors from similar to 1 to simila r to 100% of the total viable cell population, Furthermore, these chan ges in radiation response were directly reflected in the changes in tu mor oxygenation measurements made with the Eppendorf histograph, Concl usion: These findings suggest that in the KHT tumor model the Eppendor f electrode measurements could predict the response of the tumors to r adiation as determined by the proportion of hypoxic cells. (C) 1998 El sevier Science Inc.