The Principles and Practice of Re-irradiation in Clinical Oncology: An Overview.

Long-term cancer survivors are at risk of the development of recurrence or a new primary cancer that requires a second (or third) radio-oncological treatment. Publications on re-irradiation have been followed and are summarised in this overview. Information from clinical and experimental animal studies suggests that specific normal tissues can tolerate a considerable retreatment radiation dose. However, the risk of normal tissue damage and the impact on the quality of life must be considered. If a second course of radiotherapy needs to be administered, this should be done with maximum care and accuracy. Optimum conformation of the dose to the planning target volume is required. For radiobiological reasons - in order to reduce the risk of late effects - hyperfractionation protocols should be applied for curative treatments. Alternatively, small volume exposure may be considered in a highly conformal, image-guided stereotactic approach.