Human radiosensitivity: new concepts and new tools to predict the reactions after a radiotherapy

The notion of radiosensitivity is a relative notion that requires quantifications and intercomparisons. The obviousness of an individual susceptibility to radiations and a continuum of responses imposes to: work in the largest range of radiosensitivity in order to define parameters; work with human cells to avoid any way that came from differences between species; choose models and protocols as close as possible of the clinical reality (in doses, fractionation, tumor); to give a clear definition of the notion of radiosensitivity correlated with the fact to be cure by radiotherapy and the seriousness of tissues reactions. The points defining the radiobiological death are still to determine. The predictive tests based on genes expression, on the search of mutations, on the measurement of genes functions did not give convincing results. (N.C.)