[Radiosensitivity, radiocurability and DNA repair]

Improvements in accuracy stand as the heart of the success of today's radiotherapy. The dose may be delivered with a sub millimetric accuracy, may also conform to complex shapes, or track external and internal organ motions. In parallel, we may increase the tumour's radiocurability by modulating the biological effects generated by ionizing radiation into the patient. It was precisely the topic of the 2009' Lucien-Mallet prize organized by the French Society for Radiation Oncology (SFRO) and the Centre Antoine-Béclère under the auspices of the Fondation de France. In this review we will precisely describe the integrated molecular response to ionizing radiations. Starting from early observations, we are going to introduce the concept of cellular radiosensitivity as the global response of the irradiated cell. We will then focus into the cell and especially its nucleus. We will describe here the most complex and deleterious radio-induced damages. In the next chapter, we will dissect the molecular pathway that aims to detect and repair the previous lesions. The last part of the review will finally deal with the diagnostic, prognostic and therapeutic impacts emerging from the alliance between clinical and molecular radiobiology.