Radiation sensitizing effect of heat.

The radiation sensitizing effect of heat is analysed. In an isologous mouse-tumour system a successive local exposition to heat and roentgen irradiation with doses of both components of a size expected separately to give no or a few cures only an evident rise in the curative results was obtained. The presence of a synergism of the factors applied is suggested. The effect obtained depends on the dose of both factors. It is independent of the sequence of the application of the two components and is not reduced by an interval of 24 h between the exposures.