Dose dependence of reproductive lethal cell damage after X-ray irradiation or exposition to adriamycine at low doses

The effect exerted by X-rays, adriamycine and combined adriamycine and X-ray exposition on the median colony size differences (MCD) of synchronized or partially synchronized hypotetraploid CHO-T 71 fibroblasts proves that the MCD method is much more sensible in low dose regions than the normally used colony survival test. In dose regions lower than 1 Gy, the MCD shows a linear dependence on the radiation dose. As compared to the effect exerted by the cytostatic drug alone, the combined effect of adriamycine and X-rays shows a dose factor of 0,4 for the logarithmically rising scope of MCD. The possible reduction of adriamycine doses applied hitherto together with an additional irradiation provides a possibility to diminish toxic side effects for the patient and to preserve the local therapeutic effect. The authors underline the suitability of the MCD method for delicate biologic measurements on human cells in order to replace expensive experimentations on animals effected in order test the individual efficacy of therapeutic combinations of cytostatic drugs and to ameliorate the demonstration of teratogenic and carcinogenic substances and substances with other toxic effects at low active ingredient concentrations. (orig.)