Pathogenesis of late normal tissue effects

Large efforts have been made to optimize the conformation of the treatment fields to the tumor by advances in both imaging and radiotherapy technologies. However, administering sufficient dose to the target volume in curative, state-of-the-art radiotherapy still unavoidably leads to exposure of a substantial amount of normal tissue. This is associated with a risk for early and late radiation side effects and a consequential impact on the patient's quality of life. As discussed in Chapter 1, the optimal radiation dose in curative radiotherapy is the result of a balance that maximizes tumor control while minimizing normal tissue damage. Therefore, the follow-up of patients is essential to establish the efficacy and level of side effects of the treatment (20).