Estimation of normal-cell intrinsic radiosensitivity - is it a chance for radiotherapy of malignant tumors?

Benefits of the method identifying intrinsic radiosensitivity of normal-cell in cancer patients are presented. It is assumed that over 5% of the cancer patients might be radiation sensitive due to genetics. It would be valuable to identify a proportion of patients who are likely to develop the most severe complications in order to modify their therapy. It might then be possible to escalate the dose to the remaining patients to improve local tumour control. It is suggested that the subgroup of patients might tolerate reasonably high doses even up to 40% larger than the presently given, without significant increase in the risk of severe late normal-tissue complications. Advantages and disadvantages of normal-cell radiosensitivity assays are discussed. The nonclonogenic assays such as DNA damage assays (micronucleus assay) or DNA repair assays (comet assay), which evaluate lymphocytes radiosensitivity, are suggested as clinically applicable. (author)