Synergism Between Small Doses of Total-Body and Local X Radiation to Transplanted Mouse Tumors

A synergistic effect between total-body and local X-ray exposures was demonstrated in 7 transplanted tumors. The magnitude of the enhanced regression obtained with systemic irradiation varied with different tumors. The relations between the degree of synergism and the characteristics of the tumors have been considered. In general, the susceptibility to enhancement was greatest in the more radiosensitive and curable tumors. The possibility of the relations of this phenomenon to alterations in the immune process has also been considered. It was concluded that a satisfactory explanation on this basis was unlikely.