Evidence for a General Relationship between the Induced Level of DNA Double-strand Breakage and Cell-killing after X-irradiation of Mammalian Cells

X-ray-induced DNA double-strand breakage (dsb) and lethal lesion induction have been examined using normal and transformed fibroblasts of rodent and human origin. DNA dsb induction varied markedly among the different cell types and was found to reflect radiosensitivity. Linear relationships were found between DNA dsb and lethal lesion induction which were not significantly different for each cell type, suggesting a comparable probability of conversion of DNA dsb into a lethal lesion. The implications of these findings for models of cell survival are discussed.