Radiation sensitivity of leukemic progenitor cells in acute nonlymphocytic leukemia

The radiation sensitivity of leukemic progenitor cells in 12 cases of acute nonlymphocytic leukemia was compared with that of normal myeloid progenitor cells (colony-forming units in culture), using in vitro cloning techniques. The D₀value for normal colony-forming units in culture was almost constant (130 ± 14 rads). On the other hand, marked patient-to-patient variations were observed in the radiosensitivity of leukemic progenitor cells; namely, the D₀values in the present cases ranged from 30 to 210 rads. These variations seemed to be partly due to different cell cycle status and partly due to the intrinsic nature of leukemic progenitor cells. Moreover, in six of seven clinically drug-sensitive cases, the leukemic progenitor cells were proved to be relatively radiosensitive. Similar to in vitro drug sensitivity tests, this test may serve to predict the clinical response to chemoradiotherapy.