HOW MUCH COULD THE RADIOTHERAPY DOSE BE ALTERED FOR INDIVIDUAL PATIENTS BASED ON A PREDICTIVE ASSAY OF NORMAL-TISSUE RADIOSENSITIVITY

Predictive assays are presently being developed to identify the patien ts at highest risk for developing severe late normal-tissue complicati ons. If such patients could be identified prior to treatment, then the doses to those patients could be reduced to lower their complication rate. In addition, patients identified as being relatively radioresist ant could receive higher doses without an increase in complications. T he aim of the present study was to estimate the magnitude of the dose adjustments that could potentially be made if radiotherapy doses were tailored to the individual patient using a predictive assay of normal- tissue radiosensitivity. The dose adjustments were estimated by re-ana lyzing data from an earlier study [13] to determine the influence of d ose and in vitro fibroblast radiosensitivity on the incidence of sever e late normal-tissue complications. Although the dose estimates are pr eliminary and based on limited data, the results of this study support the concept that a significant therapeutic gain could be achieved for a subset of patients from the use of a predictive assay of normal-tis sue radiosensitivity.