Prof Helleday and Prof Chalmers speak to ecancer.tv about PARP inhibitors, their significance to cancer treatment and their potential for use in combination with radiotherapy. PARP inhibitors allow clinicians to target treatment specifically at the cancer cells which dramatically reduces side effects. Prof Helladay speaks about the progress that has been made bringing this technology into clinical trials and Prof Chalmers discusses the way that PARP inhibitors increase the radio-sensitivity of tumours without increasing the sensitivity of surrounding healthy tissue. Among the challenges now faced is the development of a simple and fast test to detect which cells are particularly susceptible to the PARP radiotherapy combination. Prof Chalmers and Prof Helleday speak about their hopes for developments in imaging technology, the possibility of combining PARP and radiotherapy with further radio-sensitisers and the development of recombination inhibitors.