Radiotherapy for XXXX : altered fractionation regimens.

@entity5 @entity135 @entity1 @entity189
A greater understanding of radiobiology led to the development of two classes of radiation fractionation schedules for the treatment of @entity135 . The aim of accelerated fractionation is to reduce @entity5 proliferation, which is a major cause of relapse, by shortening the total duration of radiotherapy. By contrast, hyperfractionation exploits the differential sensitivity of @entity5 cells and normal tissues to radiation, to increase the therapeutic gain. The results of clinical trials of various types of altered fractionation schedules in @entity135 are examined in this review. Acceleration of radiation by 1 week without dose reduction and hyperfractionation are consistently better than standard fractionation for locoregional control of intermediate to advanced @entity189 without an increase in late toxic effects. However, improvement in survival of @entity1 has not been consistent. Clinical investigations show that improvement in locoregional disease control and consistent gain in survival have been achieved with combinations of radiotherapy and concurrent chemotherapy in @entity1 with mostly stage IV @entity189 . However, these benefits have been at the expense of increased late morbidity. Consequently, concurrent radiochemotherapy is now preferred for non-surgical treatment of @entity1 with locally advanced @entity189 , whereas altered fractionation is generally selected for @entity1 with @entity5 or who are medically unfit to receive chemotherapy. Further data is needed before the combination of altered fractionation with chemotherapy can be recommended outside of a study setting.
