Increase in pO2 and radiosensitivity of tumors by Fluosol-DA (20%) and carbogen.

The potential usefulness of i.v. injection of perfluorochemicals and breathing carbogen (95% O2 and 5% CO2) to improve the radiation-induced control of tumors was investigated. When C3H mice, bearing RIF-1 tumors in the legs, were given i.v. injections of Fluosol-DA (20%) at 12 ml/kg, and allowed to breathe carbogen for 1 h before and during a single dose of X-irradiation, the curability of tumors increased by a dose modification factor of 1.47 +/- 0.03 (SE). Such a treatment also increased the radiation-induced skin damage by a factor of 1.15 +/- 0.12, resulting in a therapeutic gain of 1.28 +/- 0.04. Measurement of intratumor pO2 by oxygen microelectrodes demonstrated small increases in pO2 when the animals breathed carbogen, and marked increases in pO2 when Fluosol-DA (20%) was injected into the animals and the animals breathed carbogen. It was concluded that i.v. injection of Fluosol-DA (20%) followed by carbogen breathing significantly improved the oxygen supply to hypoxic cells in the RIF-1 tumors and thus increased the control of tumors by radiation.