Intrinsic radiosensitivity of healthy donors and cancer patients as determined by the lymphocyte micronucleus assay.

The purpose of the study was to evaluate the usefulness of the cytokinesis-block micronucleus (MN) assay in assessment of radiosensitivity of lymphocytes in cancer patients. Lymphocytes from 15 cervical cancer patients, 21 head and neck cancer patients, seven lung cancer patients and 19 healthy donors were analysed using MN assay. The proportion of binucleate cells (BC) in cancer patients ranged from 22 to 56% and was significantly lower than in the control group (38-68%). MN frequency assessed five times over 6 months in four healthy donors showed that the interindividual variation was significantly higher than intraindividual. Before (0 Gy) and after irradiation (2 and 4 Gy) no statistical differences in the mean number of MN/BC were observed between healthy donors and cancer patient groups. Nevertheless, statistical cluster analysis allowed each group of donors to be divided into radioresistant and radiosensitive subgroups of patients. They showed significantly different dose response. Separate comparison of the mean MN frequency within all examined radioresistant and radiosensitive subgroups, showed statistically significant differences only after a dose of 4 Gy. At this dose, the lung cancer patients and cervical cancer patients from radiosensitive subgroups presented significantly higher radiosensitivity than the healthy donors. However, healthy donors from radioresistant subgroup did not differ significantly from cancer patients. This work has shown a high variation in interindividual radiosensitivity of donors and suggests the possibility of identifying radiosensitive patients on the basis of MN assay performed on lymphocytes.