Increased radiosensitivity of tumors by perfluorochemicals and carbogen.
The efficacy of an emulsion of perfluorochemicals (Fluosol-DA) to sensitize RIF-1 tumors of C3H mice to radiation was studied. An i.v. injection of 12 ml/kg of Fluosol-DA (20%) to tumor-bearing animals and keeping the animals in an atmosphere of a mixture of O2 (95%) and CO2 (5%) (carbogen) for 1 hr before and during irradiation of s.c. tumors in the thigh significantly enhanced the tumoricidal effect of radiation as measured with growth delay of the treated tumors. A lesser but significant enhancement of radiation damage in the tumors was also observed when the animals were kept in carbogen for 1 hr without injection of Fluosol-DA. It was concluded that Fluosol-DA increased the delivery of oxygen to hypoxic areas in the tumors and enhanced the response of hypoxic cells to radiation.