Combinations of hyperthermia (40 degrees, 45 degrees C) with radiation

Incubation of Chinese hamster cells at an elevated but sublethal temperature between fractions of radiation and/or pulses of hyperthermia at 45 degrees C strongly modified the effectiveness of cell killing. Increasing the incubation temperature from 37 to 40 degrees C between fractions of hyperthermia at 45 degrees C followed by radiation substantially enhanced cell killing; while the opposite sequence (radiation leads to incubation at 40 degrees C leads to hyperthermia at 45 degrees C) resulted in less effective cell killing than would have been expected from the independent interaction of hyperthermia and radiation alone. This suggests the use of short pulses of localized hyperthermia in the presence of physiologically tolerable fever followed by irradiation as one approach to the utilization of hyperthermia in cancer therapy.