Current concepts in radiobiology applied to radiotherapy

The main research themes in radiobiology are reviewed, with an emphasis on those currently in preclinical or clinical testing. They come largely from recent insights in tumour or cellular biology and include in vivo tumour proliferation kinetics, hypoxic radioresistance, cellular or intrinsic radioresistance, the tumour's abnormal vascular bed. In order to exploit fully their therapeutic possibilities, more specific but clinically-practical methods of gauging each individual tumour's vulnerability may need to be available, so an associated line of research is the development of laboratory assays of biopsied samples to document the relevant tumour characteristics. Imaging is attractive as a relatively non-invasive means of characterising and serially sampling the tumour: this role is not yet well developed but is likely to become much more important.